Clay RSS Feed - Nonlinear_Sciences

Hybrid stars among mass gap objects are excluded by twin stars at $1.4\,M_\odot$

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2606.02593v3 Announce Type: replace-cross Abstract: We investigate the question whether compact objects in the so called mass gap ($2.5 < M/M_\odot < 5.0$) can be neutron stars or hybrid stars. Using a generic hybrid star equation of state with a first-order deconfinement transition, we map the allowed parameter space in a Seidov-type diagram and confront it with modern mass--radius constraints. We find that mass-gap hybrid stars require an extremely early onset of deconfinement and very stiff quark matter. The Bayesian analysis, however, favors equations of state with deconfinement at typical neutron-star masses around $1.4\,M_\odot$ with mass-twin stars that, if confirmed, would rule out hybrid stars as candidates for observed mass-gap compact objects.

Reference Energies for Non-Relativistic Core Ionization Potentials

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2604.05920v4 Announce Type: replace-cross Abstract: Deep-lying core electrons carry highly localized, site-specific information that forms the basis of X-ray photoelectron spectroscopy. Accurately predicting their associated core ionization potentials (IPs) is a demanding theoretical task, requiring a balanced treatment of strong orbital relaxation, electron correlation, and relativistic effects. Over the years, a variety of approaches have been developed, ranging from state-specific wave function methods to linear-response formalisms and Green's function techniques. However, their assessment has often relied on comparisons with experiment, where multiple sources of error (basis set incompleteness, relativistic corrections, and vibrational effects) are entangled, making it difficult to isolate the performance of correlation treatments. In the present work, we establish a consistent, theory-based benchmark for core IPs by computing 84 non-relativistic values (73 second-row and 11 third-row IPs) at the full configuration interaction level within the core-valence separation approximation, using large correlation-consistent basis sets augmented with tight-core and diffuse functions (aug-cc-pCVXZ). These results define theoretical best estimates within a fixed finite basis set, providing a chemically accurate reference for method development and validation. Importantly, our dataset allows for systematic, theory-versus-theory comparisons that disentangle correlation and relaxation effects from other physical contributions. On this basis, we assess the performance of widely used approximate methods, including equation-of-motion coupled-cluster approaches up to the inclusion of quadruple excitations, the one-shot $G_0W_0$ scheme, as well as state-specific methods.

Dispersive Analysis of $D$- and $B$-Meson Form Factors with Chiral and Heavy-Quark Constraints

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2603.11154v2 Announce Type: replace-cross Abstract: We analyze the isovector vector form factors of $D$, $D^*$, $B$, and $B^*$ mesons at low energies. We employ all constraints due to chiral and heavy-quark symmetry, and include the physics of resonant pion-pion rescattering in a model-independent way, using dispersion theory. Special attention is paid to the analytic properties of these form factors, which include anomalous thresholds due to triangle diagrams that are located on the physical Riemann sheets in some of the form factors. We extract the couplings of the $\rho(770)$ resonance to all these heavy mesons by determining the appropriate pole residues.

Isentropic thermodynamics across the hadron-quark mixed phase in a two-phase model with a PNJL quark description

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2603.11081v2 Announce Type: replace-cross Abstract: We study the hadron-quark mixed phase within a two-phase model for symmetric and asymmetric matter. For the quark sector we employ the (2+1) Polyakov-extended Nambu-Jona-Lasinio model (PNJL) with vector interactions. We investigate how the hadronic equation of state affects the phase diagram and the thermodynamic properties inside the mixed phase. The behavior of isentropic trajectories in the mixed phase depends on the fixed entropy per baryon ($s/\rho_B$), with trajectories near the critical end point (CEP) exhibiting a pronounced cooling pattern, while isentropic trajectories with low entropy per baryon undergo pronounced heating as the baryonic density increases. The adiabatic squared speed of sound displays characteristic peak and dip structures that depend on $s/\rho_B$. The polytropic index along isentropic and isothermal trajectories, including in the vicinity of the CEP are also investigated. The effects of vector interactions and isospin asymmetry on thermodynamic observables likewise depend on the chosen $s/\rho_B$ value. Finally, we discuss the population of hyperons along isentropic trajectories and their influence on the phase diagram. The main effect of hyperons is to shift the onset of deconfinement to larger densities and decrease the density extension of the mixed phase.

Saturation effects in exclusive vector meson production in DIS

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2511.22763v3 Announce Type: replace-cross Abstract: We investigate saturation effects in exclusive vector meson production in deep inelastic scattering (DIS), where we model fluctuations within the target protons as localized color-charge hotspots. Based on the Color Glass Condensate (CGC) framework and the dipole picture for vector meson production, we examine the dependencies of coherent and incoherent scattering cross sections on the momentum transfer. We draw conclusions on the effectiveness of our hot spot model and the strength of the suppression of the scattering cross sections caused by saturation effects. We find that saturation has mild effects in the given energy and charge-density ranges, but can also show that suppression becomes more prominent as the color-charge density inside the proton increases.

Scaling behaviour of charged particles generated in Xe$-$Xe collisions at $\sqrt{s_{\rm{NN}}}$ = 5.44 TeV using the AMPT model

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2508.12796v3 Announce Type: replace-cross Abstract: The spatial configurations of particles produced in the kinematic phase space during a heavy-ion collision reflect the characteristics of the system created in the collision. The scaling behaviour of the multiplicity fluctuations is studied for the charged particles generated in Xe--Xe collisions at $\sqrt{s_{\rm{NN}}}$~=~5.44~TeV using the String Melting (SM) mode of the AMPT (A Multi-Phase Transport) model. The scaling behaviour of the normalized factorial moments ($F_\text{q}$) gives significant information about the dynamics of the system under study. A linear power-law growth of the $F_\text{q}$ with the increasing phase space resolution, termed as intermittency, is investigated. The anomalous fractal dimension $D_\text{q}$ is determined, which is linked to the self-similarity and fractal nature of the particle emission spectra, whose dependence on the order of the moment ($q$) is characterised by the intermittency index ($\varphi_{\text{q}}$). Relating $q^{\rm{th}}$ order Normalised Factorial Moment (NFM) with $F_{2}$, the scaling exponent ($\nu$) is determined that quantifies the dynamics of the system created by these collisions and is analyzed for its dependence on the transverse momentum bin width ($\Delta p_\text{T}$). Results presented may be interpreted as model predictions and baseline expectations.

Breakdown of Smooth Shock Solutions in Transient Relativistic Hydrodynamics

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.15756v2 Announce Type: replace Abstract: In this work, we demonstrate that shock solutions in the Israel-Stewart framework lose regularity once the shock velocity reaches a critical value, and a discontinuity emerges in the solution, which can be interpreted as a second shock wave. This subshock arises as a consequence of the finite speed of information propagation inherent to the Israel-Stewart theory. We then perform numerical simulations to confirm the breakdown of solution continuity. Subsequently, we propose two regularization procedures to extend the domain of continuous shock solutions. The first employs a third-order extension, which introduces new kinetic fields, while the second incorporates a small numerical bulk viscosity. Both methods effectively increase the maximum propagation speed of the Israel-Stewart theory and extend the range over which regular shock solutions exist. Thus, we confirm that this loss of regularity is a direct consequence of the Israel-Stewart framework. These results suggest that Israel-Stewart theory may not provide an adequate description of ultra-relativistic shock waves.

Attractodynamics in 0+1D

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.16393v1 Announce Type: cross Abstract: Hydrodynamics is a macroscopic theory of long-wavelength dynamics around local thermal equilibrium. We develop attractodynamics, the analogous construction around a far-from-equilibrium attractor. Dynamics near a far-from-equilibrium attractor retains some non-hydrodynamic microscopic information, which attractodynamics systematically organizes. We move towards this general structure by starting in 0+1D, and consider a model for which an anisotropic far-from-equilibrium attractor solution is exactly known. This setting provides a clean benchmark in which the ideal attractodynamic equations and a leading transient residual extension can be compared directly with the full kinetic evolution. The resulting hierarchy gives an improvable description of near-attractor dynamics: the ideal theory captures evolution close to the attracting manifold, while retaining the leading off-attractor moments extends the regime of agreement until the finite truncation breaks down. This example identifies the ingredients needed for local 3+1D attractodynamics and for macroscopic attractodynamic theories not derived from an underlying kinetic description.

Sensitivity of p_T Fluctuations to the QCD Equation of State

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.18211v1 Announce Type: new Abstract: We construct a novel theoretical baseline for dynamical transverse momentum correlations, $C_{pT}$, across a wide range of collision energies spanning the RHIC Beam Energy Scan (BES) program. For the first time, a unified framework is developed to describe the energy and centrality dependence of $C_{p_{\rm T}}$ from $\sqrt{s_{\text{NN}}} = 3.0$ to $200$~GeV. A central feature of this study is the implementation of Equation of State (EOS) inputs derived from Lattice QCD results at finite baryochemical potential $\mu_{\rm B}$, representing the first such application to the measured transverse momentum correlations. Despite the minimalist nature of the fluid-dynamic evolution employed, the model effectively captures the characteristic centrality scaling of the experimental data. Our results indicate that while the bulk evolution is largely governed by the EOS and system lifetime at lower energies, significant deviations in peripheral collisions at top energies highlight the onset of non-thermal correlation mechanisms. This baseline provides a necessary benchmark for interpreting transverse momentum fluctuations in heavy-ion collisions and can aid in the search for the QCD critical point.

Dissipative properties of a Fermi system within the diffusion approximation of kinetic theory

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17837v1 Announce Type: new Abstract: The dissipative properties of a Fermi system are studied within the diffusion approximation of kinetic theory for a model of a spherical atomic nucleus. An analytical solution of the nonlinear diffusion equation in energy space with constant kinetic coefficients is used to show that the distribution function asymptotically approaches the equilibrium Fermi distribution. It is found that the deviation from equilibrium at finite times decays with an effective relaxation time of $\tau_\mathrm{eff}\approx 1.0\times10^{-23}$ s, whereas the asymptotic regime is characterized by an exponential decay with a relaxation time of $\tau_\mathrm{eq}\approx 3.2\times10^{-23}$ s. These results explain the difference between the relaxation times extracted from integral characteristics of the relaxation process and from the asymptotic long-time evolution.

Trace anomaly and isospin splitting in inverse-mapped relativistic mean-field theory

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17472v1 Announce Type: new Abstract: Trace anomaly and sound speed provide EOS-level probes of dense-matter nonconformality, but do not by themselves identify the microscopic channels responsible for the response. We study this question with a uniform-matter inverse-mapped relativistic mean-field ensemble constrained by chiral effective field theory, heavy-ion flow information, and neutron-star mass-radius data. The ensemble reproduces the flow-based trace trend in symmetric nuclear matter, while beta-equilibrated matter approaches the neutron-star trace bands more slowly. The resulting splitting, $\Delta_{\SNM}-\Delta_{\betaeq}$, remains positive over $2--5\nzero$ and is most strongly correlated with the density derivative of the isovector-vector coupling, with bootstrap-stable Spearman coefficients $r_s\simeq0.91--0.92$ at $2--3\nzero$. Its correlation with the beta-equilibrium proton fraction is much weaker. The sound-speed splitting changes sign near $3.38\nzero$, and the derivative term $-\dd\Delta/\dd\ln\varepsilon$ becomes sensitive to both scalar-vector and isovector responses above $4\nzero$. Data-combination and controlled-isovector tests show that this channel separation is resolved only when laboratory and astrophysical projections are combined. Thus, within the present inverse-mapped RMF space, the SNM--beta trace splitting acts as a thermodynamic probe of the high-density symmetry sector rather than as a unique signal of exotic degrees of freedom. A finite-nucleus-calibrated extension will be needed to test how much of this channel diagnostic survives in predictive covariant density functionals.

Rapidity-even Dipolar Flow in Relativistic Heavy-Ion Collisions

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17449v1 Announce Type: new Abstract: Rapidity-even directed flow, ($v_{1}^{even}$), provides a sensitive probe of fluctuation-driven dipolar asymmetry in the initial state of relativistic heavy-ion collisions. Its extraction is complicated by large first-harmonic non-flow correlations, particularly those induced by global momentum conservation (GMC). In this work, we study ($v_{1}^{even}$) and its multi-particle correlations in Au+Au collisions at ($\sqrt{s_{NN}}=200$) GeV using the AMPT and HIJING models. An ($\eta$)-dependent weighting procedure is employed to suppress the leading GMC contribution. HIJING is used as a non-collective baseline, while AMPT is used to investigate sensitivity to final-state partonic transport. The GMC-corrected HIJING results are strongly reduced for most ($v_1$)-related observables, indicating that the leading HIJING-like recoil contribution is effectively mitigated. The AMPT calculations reproduce the characteristic sign-changing ($p_T$) dependence of ($v_{1}^{even}$) and show sensitivity to the partonic scattering strength. Mixed-harmonic and normalized correlations involving ($v_1$), ($v_2$), and ($v_3$) suggest that the dipolar mode is correlated with both the elliptic geometry and fluctuation-driven triangular structure. These results demonstrate that GMC-suppressed rapidity-even dipolar-flow correlations provide a promising framework for constraining initial-state fluctuations and final-state transport in heavy-ion collisions.

Chemonuclear Transmutation and Noble Metal Synthesis

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17238v1 Announce Type: new Abstract: In the system of metallike hydride-electron donor mixtures, adsorbed hydrogen atoms are transformed into metallic states and alloyed. Dense itinerary s-electrons supplied by the electron donor cause a drop in the melting point of metallic hydrogen. As a result, this system reveals thermodynamical liquid activity. The coherent D2-D2 fusion and the D3-D3 chemonuclear fusion are enhanced with factors of 20 to 30 and 30 to 46 figures of magnitude respectively at T=460 K, hence the production of intense He ions of 23.8 MeV kinetic energy. The ions or alpha-particles induce enhanced cascade chemonuclear reactions towards diverse and useful element synthesis. This phenomenon is in the nature of the Big Bang nucleosynthesis that takes place in an inhomogeneous universe. An application of the alpha-induced chemonuclear reaction - i.e., the transmutation of 90Sr and 137Cs - is prescribed in this chapter. This system of metallike hydride-electron donor mixtures raises the possibility of radioactive waste vanishment. Stimulated by alpha-particle irradiation, trans-gold nuclei undergo exothermic alpha-cluster emissions, producing coherently line-up alpha-clusters. In the chemonuclear D-D fusion, the 4alpha-cluster reveals the thermodynamical activity of oxygen atoms. In the hydrogen-Ni nanopowder-Li mixtures, dispersively charged trans-gold atoms undergo enhanced chemonuclear alpha-cluster emissions, hence the mass synthesis of noble metals. The case of chemonuclear pion production is presented at the end of this chapter.

Coulomb interaction in the diffraction description of the $^{12}$C(d,p)X reaction

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17222v1 Announce Type: new Abstract: Within the Glauber-Sitenko diffraction multiple-scattering theory, we calculate Coulomb corrections to the invariant cross section for inclusive deuteron breakup in the $^{12}$C(d,p)X reaction at small proton emission angles. Extending our previous analysis of the longitudinal momentum transfer $Q_z$ and the transverse relative momentum of the final $pn$ pair, we include the proton--nucleus electromagnetic interaction, Coulomb-nuclear interference, and the Coulomb correction to double $pn$ rescattering. For a finite nuclear charge distribution, we derive the Coulomb phase and relate its spatial scale to the measured charge radius. Closed and Yukawa-screened expressions for the proton Coulomb term are obtained. The two-dimensional correction to $pn$ rescattering is reduced to a one-dimensional integral without an independent Gaussian approximation to the full transition form factor. Calculations with the $S$-wave components of the K2 and Nijm-I deuteron wave functions show that the Coulomb effect is concentrated near the quasifree peak. Its interference with the strong amplitude increases the peak height but decreases rapidly with relative momentum. It therefore cannot explain the experimental enhancement at $0.3$--$0.5$ GeV/$c$, where final-state interactions, relativistic corrections, and nonnucleonic components may be important.

Kaon-induced $\phi \Sigma$ production off the proton

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17156v1 Announce Type: new Abstract: We investigate the reaction mechanism of $K^-p \to \phi\Sigma^0$ within a hybrid Regge approach based on effective Lagrangians. The nonresonant background includes Reggeized $t$-channel $K$ and $K^*$ exchanges, together with ground-state $\Sigma$ and nucleon exchanges in the $s$ and $u$ channels, respectively. To describe the structures observed at $3.0 \leqslant P_{\rm Lab} \leqslant 4.5$ GeV, we include the high-mass $\Sigma(2620)$ and $\Sigma(3000)$ resonances and examine the spin-parity assignments $J^P = 1/2^\pm$, $3/2^\pm$, and $5/2^\pm$. The $K^*$-Reggeon exchange dominates the forward-angle cross sections, whereas the smaller $K$-Reggeon contribution is important for the total cross section at low energies and for the spin-density matrix elements. The nonresonant background alone is not sufficient to reproduce the local structures in the total cross section or the differential cross sections at large $-t'$. Including the two resonances, particularly the $\Sigma(3000)$, substantially improves the agreement with the available data. The $J^P=5/2^-$ assignment for the $\Sigma(3000)$ provides a reasonable overall description, although the present data do not permit a definitive determination.

Finite-nucleus-protected high-density extension of covariant density functionals constrained by multimessenger data

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.16683v1 Announce Type: new Abstract: We construct a finite-nucleus-protected high-density extension of covariant density functionals by modifying only the isoscalar-vector channel outside the finite-nucleus calibration domain. The extension introduces three parameters controlling the strength, onset, and width of the high-density deformation, while the scalar and isovector channels are kept unchanged. A Bayesian analysis using heavy-ion flow constraints, massive-pulsar information, NICER mass-radius measurements, and the GW170817 tidal constraint shows that the original \ddme interaction is strongly disfavored relative to its protected high-density extension, with $\ln K=\ln(Z_{\rm ext}/Z_{\rm base})=26.67$, where $Z$ denotes the Bayesian evidence, after imposing a causal/stability filter on the reshaped EOS. In contrast, \ddpc serves as a reference functional for which the same extension is not required by the present data, giving $\ln K=-0.44$. The result supports the interpretation that the proposed extension is not an unconstrained phenomenological patch: Bayesian evidence selects it only when demanded by the combined high-density data, while finite-nucleus observables remain unchanged within numerical precision.

Search for $\Xi^0p$, $\Omega^- p$, and $\Omega^- n$ dibaryons in $\Upsilon(1S)$ and $\Upsilon(2S)$ decays at Belle

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2605.29778v2 Announce Type: replace-cross Abstract: We search for $\Xi^0p$, $\Omega^-p$, and $\Omega^-n$ dibaryon states in $\Upsilon(1S)$ and $\Upsilon(2S)$ decays, probing mass regions near the corresponding baryon-pair thresholds. Multistrange baryon-baryon interactions are relevant to neutron-star matter but remain largely unconstrained. Experimental and theoretical studies supporting attractive $\Xi N$ and $\Omega N$ interactions, where $N$ denotes a nucleon, motivate searches for weakly bound states. We use samples of $102$ million $\Upsilon(1S)$ and $158$ million $\Upsilon(2S)$ decays collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. No significant signals are observed, and the first $90$% confidence-level upper limits are set on the branching fractions of $\Upsilon(1S)$ and $\Upsilon(2S)$ decays to $\Xi^0p$, $\Omega^-p$, and $\Omega^-n$ dibaryon states, at the level of $O(10^{-7})$-$O(10^{-6})$, depending on the channel and the assumed mass difference from the corresponding baryon-pair threshold.

Extracting the speed of sound of QCD from transverse momentum fluctuations

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2603.09647v2 Announce Type: replace-cross Abstract: We extract the speed of sound ($c_s$) in the quark-gluon plasma from ATLAS data on the probability distribution of the transverse momentum per particle, $[p_T]$, in ultra-central Pb+Pb collisions. With an ideal detector, $c_s$ can be inferred from the rise of the mean $[p_T]$ with the collision multiplicity. In practice, however, low-$p_T$ particles escape detection, which biases the analysis. We show how to correct for this bias by using data on the variance of $[p_T]$, as well as information from the recently-measured $v_0(p_T)$. We also introduce a systematic method for deblurring the noise from the hadronization process. Assuming that the size of the quark-gluon plasma is independent of the hadron multiplicity in collisions at zero impact parameter, which is the scenario preferred both by high-energy QCD and heavy-ion data, we obtain $c_s/c=0.496\pm 0.008$ at temperature $T=221\pm 13$~MeV, in perfect agreement with first-principles calculations from lattice QCD.

Facilitating neutron and energy reconstruction in neutrino events using the direction of tagged neutrons

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2509.17123v2 Announce Type: replace-cross Abstract: To date, accelerator neutrino experiments have had only limited success including neutrons in the neutrino event reconstruction event by event. Produced neutrons often interact in a detector leaving an energy deposition that does not correlate strongly with the kinetic energy of the neutron. This work explores the inclusion of the direction of a neutron tagged by such an energy deposition in concert with the missing transverse momentum of the reconstructed particles to determine the approximate kinetic energy of the neutron and modify the reconstruction of the energy of the incoming neutrino. The technique significantly increases the neutron kinetic energy estimation relative to one that assigns the neutron kinetic energy by enforcing transverse momentum balance alone. When included in the neutrino energy calculation, the neutrino energy resolution is improved and the reconstructed energy is distributed more symmetrically around the true value. The technique shows promise and might be used to good effect to analyze data taken with experiments able to tag neutron energy deposits with good neutron direction resolution such as the T2K near detector and the liquid argon detectors in the SBN program and DUNE.

Production and spectroscopy of cold radioactive molecules

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2508.08368v2 Announce Type: replace-cross Abstract: Molecules with heavy, radioactive nuclei promise extreme sensitivity to fundamental nuclear and particle physics. However, these nuclei are available in limited quantities, which challenges their use in precision measurements. Here we demonstrate the gas-phase synthesis, cryogenic cooling, and high-resolution laser spectroscopy of radium monohydroxide, monodeuteroxide, and monofluoride molecules ($^{226}$RaOH, $^{226}$RaOD, and $^{226}$RaF) in a tabletop apparatus by combining novel radioactive target production protocols, optically driven chemistry in a cryogenic buffer gas, and low-background spectroscopic detection methods. The molecules are cooled in the lab frame, creating conditions that are the same starting points as many current molecular precision measurement and quantum information experiments. This approach is readily applied to a wide range of species and establishes key capabilities for molecular quantum sensing of exotic nuclei.

Neutron EDM Experiment with an Advanced Ultracold Neutron Source at TRIUMF

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2507.05278v4 Announce Type: replace-cross Abstract: The TRIUMF Ultracold Advanced Neutron (TUCAN) collaboration has been developing a high-intensity ultracold neutron (UCN) source aimed at searching for the neutron electric dipole moment (EDM) with a sensitivity goal of $10^{-27}\ e{\rm cm}$. This article reports on recent progress in commissioning of the UCN source and in the development of the neutron EDM spectrometer. In its final configuration, the accelerator-driven super-thermal UCN source will enable a neutron EDM experiment with two orders of magnitude improved statistics compared to the current best experiment. Substantial progress in 2024 allowed the collaboration to operate the complete source system, with the exception of the liquid deuterium cold moderator, resulting in the first production of UCNs. The status of the EDM spectrometer is also presented, with emphasis on UCN handling components and magnetic subsystems relevant to field control, shielding, and magnetometry.

Measurements of jet quenching with semi-inclusive hadron-jet correlations in Ru+Ru and Zr+Zr collisions at $\sqrt{s_\mathrm{NN}}=200$ GeV

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2606.00973v3 Announce Type: replace Abstract: The STAR experiment at RHIC reports measurements of the semi-inclusive yield of charged-particle jets recoiling from high transverse momentum charged-hadron triggers in centrality-selected Ru+Ru and Zr+Zr collisions at the nucleon-nucleon center-of-mass energy of 200 GeV. The effects of jet quenching, arising from the interaction of jets with the quark-gluon plasma, are quantified by comparing trigger-normalized recoil yields in central and peripheral collisions. Suppression of the recoil yield in central collisions is observed, indicating medium-induced partonic energy loss due to quenching. The ratio of recoil jet yields for small and large resolution parameter is found to be suppressed in central relative to peripheral collisions, characteristic of medium-induced intra-jet broadening. The results are compared to similar measurements in smaller and larger collision systems, providing unique insight into the system-size dependence of jet quenching.

Two-dimensional Optical Parallel-Plate Avalanche Counter (OPPAC) with SiPM optical readout for heavy-ion tracking

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17013v1 Announce Type: cross Abstract: We report the progress achieved on the development of a two-dimensional Optical Parallel-Plate Avalanche Counter (OPPAC) prototype for heavy-ion tracking. The device consists of two uniform thin parallel plates of 10 x 10 cm2 effective area, separated by a gap of 3 mm. The gap is filled with Tetrafluoromethane (CF4) at low pressure (up to 50 Torr). By applying a voltage difference between parallel plates, a uniform electric field is established within the gap. Electroluminescence emission is produced during the electron avalanche triggered by a charged particle that crosses the gas gap. The light is detected by an optical readout comprising four arrays of collimated Silicon Photomultipliers (SiPMs) deployed around the gas gap. The position of the particles is reconstructed by processing the light signals collected by all the SiPMs by computing the center of gravity of the light distribution within the SiPM arrays. The SiPM signals are read out and processed by a data acquisition (DAQ) system based on the General Electronics for TPC (GET). Preliminary results from a test with an alpha-particle source and a 100 MeV/u 40Ca beam demonstrate a sub-millimetre intrinsic position resolution sigma_det = 0.7 mm) while preserving good linearity over the entire detector active area.

Wounded parton scaling of multiplicities in ultra-relativistic light- and heavy-ion collisions

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.16485v1 Announce Type: cross Abstract: Multiplicities of charged particles produced in O+O, Ne+Ne, Xe+Xe, and Pb+Pb collisions at $\sqrt{s_{NN}} \sim 5$~TeV are studied in a uniform way within a wounded parton Glauber framework with overlaid negative binomial fluctuations. In this model, the nucleon's inelastic interaction is modeled via its constituent partons, whose number is a parameter, with best description obtained with four partons per nucleon. We fit directly the experimental multiplicity distributions (histograms), using {\it the same model parameters} for each reaction. The fit is performed in the c=1--80 $\%$ centrality range. Avoiding the most peripheral events makes the method insensitive to the normalization issues caused by the difficulty in separating the Coulomb interactions, whereas the most central collisions may involve a different particle production mechanism. We find a proper model description of multiplicity distributions across all the studied systems for $c \lesssim 1\%$.

Long-Lived Dark Hadrons at the Electron-Ion Collider

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.16400v1 Announce Type: cross Abstract: We study a dark non-Abelian gauge sector with GeV-scale confinement. The dark sector is assumed to couple only feebly to the Standard Model, while its low-energy spectrum may contain long-lived flavor-diagonal dark pions. Signals of these states are particularly well suited to the Electron-Ion Collider (EIC), where the absence of a hard trigger requirement and the capability to record soft final-state particles offer a complementary probe of dark hadronization dynamics. We present a benchmark portal construction, discuss the mixing between an axion-like mediator and dark pions, and identify the resulting displaced-decay signature.

Transverse Charge Distribution as a Probe of Nucleon Transversity

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.16392v1 Announce Type: cross Abstract: We introduce the transverse charge distribution as a spin-sensitive charge-flow probe for fragmentation and nucleon tomography. By measuring the angular distribution of net electric charge around a fragmenting quark, this observable relies entirely on the tracking of charged-particle directions and charge signs, strictly bypassing the need for calorimetric energy measurements. At leading twist, the distribution decomposes into an unpolarized charge monopole and a chiral-odd transverse charge dipole. We derive the operator product expansion of these distributions onto charge-weighted collinear moments: the monopole is fixed by charge conservation, while the dipole is governed by the Collins effect and couples directly to transversity. Applying this formalism to transversely polarized $p^\uparrow p$ collisions at RHIC, we show that charge weighting suppresses the unpolarized monopole background and causes the spin-dependent dipoles from oppositely charged hadrons to add coherently. This coherence strongly enhances the resulting azimuthal asymmetries, establishing a theoretically clean and experimentally precise track-only avenue for extracting transversity.

First measurement of $\mathbf{\rm \Xi_{\rm c}^{0}}$ production in $\mathbf{Pb}-\mathbf{Pb}$ collisions at $\mathbf{\sqrt{\textit{s}_{\rm NN}}}$ = 5.02 TeV

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17903v1 Announce Type: new Abstract: The ALICE Collaboration reports the first measurement of the production of prompt $\Xi_{\mathrm c}^{0}$ baryons in nucleus$-$nucleus collisions by analyzing data from $\mathrm{Pb}-\mathrm{Pb}$ collisions at $\sqrt{s_{\mathrm{NN}}}~=5.02~\mathrm{TeV}$. The production and transverse-momentum ($p_{\mathrm T}$) differential spectra of $\Xi_{\mathrm c}^{0}$ are particularly sensitive to the hadronization process and to strangeness production in the quark--gluon plasma formed in high-energy heavy-ion collisions. The $\Xi_{\mathrm c}^{0}$ baryons are reconstructed at midrapidity ($|y|<0.5$) in the transverse-momentum intervals $3

Symplectic mechanics of relativistic spinning compact bodies. III. quadratic-in-spin integrability in Type-D Einstein spacetimes: persistence and breakdown

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2601.06416v2 Announce Type: replace-cross Abstract: We investigate the integrability of spinning compact body dynamics at quadratic order in spin in four-dimensional Einstein spacetimes admitting a non-degenerate Killing--Yano tensor. Working within the Mathisson--Papapetrou--Tulczyjew--Dixon framework under the Tulczyjew--Dixon spin supplementary condition, we model the spin-induced quadrupole with a deformability parameter $\kappa$, where $\kappa=1$ corresponds to black holes. The dynamics is formulated as a Hamiltonian system on a 10-dimensional physical phase space obtained by Dirac--Bergmann reduction. For $\kappa=1$, we establish Liouville--Arnold integrability at quadratic order in spin by constructing five independent, Poisson-commuting first integrals, including a generalization of the Carter constant and the R\"udiger constant to quadratic-in-spin order in Einstein spacetimes beyond Kerr. For $\kappa \neq 1$, the R\"udiger and Carter constants are no longer conserved; integrability does not persist at this order. All our results are carried out in a covariant manner and numerically verified, and Kerr is recovered as a special case. These results show that integrability can extend beyond Kerr and beyond the linear-in-spin regime, while its breakdown for $\kappa \neq 1$ points to the spin-induced quadrupole as a decisive probe of compact body structure.

Real-Spectrum Darboux Limits at Multiple Spatial Roots of the Coupled Fokas-Lenells System

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17955v1 Announce Type: new Abstract: We investigate Darboux constructions generated by multiple spatial roots of the coupled Fokas-Lenells system on a plane-wave background. Nonreal double roots give regular one-fold transformations, whereas real double and triple roots require directional real-spectrum limits. We classify the admissible projective null sets, derive the leading spectral corrections, and establish global regularity. A critical background relation additionally produces a persistent zero branch, leading to distinct nonlocal plateaus along parabolic corridors, cubic level sets, and a characteristic line.

Integrable Volterra hierarchies over nonabelian algebras

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17868v1 Announce Type: new Abstract: Known integrable systems with noncommutative dependent variables are typically formulated over free associative algebras, quantum algebras, or Grassmann algebras. For differential-difference integrable equations, we identify a new class of noncommutative algebras that is compatible with the dynamics and can be positioned between quantum and free algebras. In this brief communication, we consider reductions of the nonabelian Volterra hierarchy to new algebras. This approach extends to a broad class of integrable systems, including the Toda lattice, the Ablowitz-Ladik system, and many others.

Crossovers from nonlinear wave-packet acceleration to wave-mixing and self-trapping in the Hatano-Nelson model

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2604.02263v2 Announce Type: replace-cross Abstract: We demonstrate that wave amplification enables even weak nonlinearities to reshape linear wave-packet transport in nonreciprocal systems. We study the dynamics of bulk Gaussian wave-packets in the Hatano--Nelson model with on-site cubic nonlinearity. We show that the interplay between nonlinearity and amplification generates growing frequency shifts that drive the wave-packet through three successive dynamical regimes: an early nonlinear-skin regime with coherent propagation, an intermediate wave-mixing regime driven by eigenmode resonances, and a self-trapping regime in which part of the packet localizes while the remainder ballistically spreads along the system favored direction. The crossover time scales are set by the width and averaged spacing of the eigenfrequency spectrum. Crucially, within the nonlinear-skin regime, we derive analytical predictions for the wave-packet dynamics and show that nonlinearity couples amplification, dispersion, and nonreciprocity, thereby modifying the magnitude of the wave-packet acceleration and introducing an explicit time dependence into its evolution. Focusing nonlinearities suppress the acceleration and cause it to decrease in time, whereas defocusing nonlinearities enhance it and cause it to increase. We further show that nonlinear interactions typically break down the wave-packet before the non-Hermitian jump can occur. Our results provide a route toward accurate control of waves in nonreciprocal metamaterials.

Turing patterns in Matrix-Weighted Networks

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2602.13080v2 Announce Type: replace-cross Abstract: Diffusion-driven instability is a fundamental mechanism underlying pattern formation in spatially extended systems. In almost all existing works, diffusion across the links of the underlying network is modeled through scalar weights, possibly complemented by cross-diffusion terms that are homogeneous across links. In this work, we investigate the emergence of Turing patterns on Matrix Weighted Networks (MWNs), a recently introduced framework in which each edge is associated with a matrix weight. Focusing on the class of coherent MWNs, we provide a novel characterization of coherence in terms of node-dependent orthonormal matrices, showing that link transformations can be written as relative rotations between nodes. This representation allows us to deal with coherent MWNs of any size and to introduce an orthonormal change of variables capable to reduce diffusion on a coherent MWN to diffusion on a standard weighted network with scalar weights. Building on this, we extend the classical Turing instability analysis to MWNs and derive the conditions under which a homogeneous equilibrium of the local dynamics loses stability due to matrix-weighted diffusion. Moving beyond the dimensional constraints of previous approaches, our results show how network topology, scalar weights, and inter-node transformations jointly shape pattern formation, and provide a constructive framework to analyze and design Turing patterns on matrix-weighted and higher-order networked systems.

Transition to chaos in two-dimensional Rayleigh-B\'enard convection: the role of the magnetic field

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17918v1 Announce Type: cross Abstract: The impact of an externally imposed magnetic field on numerical simulations of two-dimensional Rayleigh-B\'enard convection (RBC) is investigated. Initially, the RBC model is examined in the absence of a magnetic field to establish a baseline. Then, a background magnetic field is introduced, and its influence on the transition to chaos is explored. For the purely hydrodynamic case and a range of the reduced Rayleigh number, the system exhibits traveling rolls which, after an attractor-merging crisis, give way to chaotic traveling rolls. Upon imposing a background magnetic field, there is a notable increase in the occurrence of traveling roll dynamics. Furthermore, the presence of the magnetic field favors the splitting/breaking of convective rolls, indicating a possible mechanism for transition to two-dimensional turbulence, with the structure of the convection cell being disrupted. A detailed analysis of the velocity field reveals that the collision between a saddle point and the center of a convective roll restores the system's original topology, with two symmetric kinetic vortices. During this collision, a magnetic vortex splits in two as a result of a magnetic reconnection. This behavior occurs intermittently in time.

Two-dimensional solitons in extended GPE models with Lee-Huang-Yang corrections

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.16820v1 Announce Type: cross Abstract: We investigate the existence and dynamics of two-dimensional solitary waves in a quantum droplet environment described by the extended Gross-Pitaevskii equation featuring logarithmic mean-field and Lee-Huang-Yang interactions. In the modulationally stable regime of the background, we employ suitable multiscale asymptotic methods to derive effective nonlinear integrable models corresponding to the Kadomtsev-Petviashvili and Davey-Stewartson equations. Based on these reduced models, we construct approximate analytical solutions describing line solitons, algebraically localized lump solitons, ring solitons, and exponentially localized dromions embedded on the droplet background. The dynamical robustness of these solutions is monitored through numerical simulations. Line, lump and ring solitons stay closest to the theoretical predictions, although progressively deviate due to the emergence of small-amplitude radiation, while dromions depart from their analytical waveform the most, although they roughly maintain their shape. Our results unveil unprecedented multidimensional soliton solutions in models featuring the competition of mean-field and quantum fluctuations and as such are amenable to current ultracold atom experiments.

Quiescent and traveling solitons in the fractional parametrically driven damped nonlinear Schr\"{o}dinger equation

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17446v1 Announce Type: new Abstract: We systematically investigate the existence, stability, and dynamics of optical solitons in the framework of the one-dimensional nonlinear Schr\"{o}dinger equation with the Riesz-fractional diffraction operator, cubic self-focusing, and linear loss, balanced by a linear parametric drive. The model, which can be realized in a laser cavity, produces standing and moving solitons, the latter ones existing below a critical velocity. One of the soliton species is stable in a wide range of parameters, while others are unstable. The fractional diffraction significantly alters the existence conditions and stability thresholds of the solitons. Collision between moving solitons are considered too. The results essentially expand the variety of nonlinear modes in media with fractional diffraction.

Beyond the Edge of Chaos: Stability-Expressivity Transfer in Reservoir Forecasting

Tue, 21 Jul 2026 00:00:00 -0400

arXiv:2607.17909v1 Announce Type: cross Abstract: The edge-of-chaos heuristic has long served as a guiding principle for designing reservoir computers, yet its relevance to machine performance remains elusive. Here, taking the spectral radius of the reservoir network as the control parameter, we show that the radius yielding the best forecasting performance does not coincide with the Lyapunov edge of the isolated, teacher-forced, or closed-loop generative reservoir. By analyzing the collective dynamics of the teacher-forced reservoir, we find that the target dynamics are represented mainly by stable Lyapunov modes whose finite-time stability is strongly modulated by the input. This finding motivates a stability-expressivity transfer index, which balances the stability of these modes against their expressivity in representing the target. Across chaotic and quasiperiodic targets, and for both asymmetric and symmetric reservoirs, this index accurately identifies the optimal spectral radius for autonomous forecasting.

Effect of the near-proton-emission threshold resonance in $^{11}$B on the branching ratio of beta-delayed proton emission from $^{11}$Be

Mon, 20 Jul 2026 00:00:00 -0400

arXiv:2411.10700v2 Announce Type: replace-cross Abstract: Beta-delayed proton emission from neutron halo nuclei $^{11}\mathrm{Be}$ represents a rare decay process. The existence of the narrow resonance near the proton-emission threshold in $^{11}\mathrm{B}$ explains its unexpectedly high probability. However, the accurate value of the branching ratio remains challenging to determine. We aim to quantify the influence of the narrow resonance near the proton emission threshold on the result of the branching ratio. We employ the Skyrme Hartree-Fock calculation within the potential model to obtain the branching ratio. We derive the single-particle potentials for the halo neutron and the emitting proton with minimal adjustment. Slight variations in the resonance position significantly impact the branching ratio, with the upper limit reaching the order of $10^{-5}$. Experimental determination of the resonance energy, particularly whether it lies below $200$ keV, is crucial for determining the value of the branching ratio.

Universal Properties of Near-Threshold Single-Neutron Resonances

Mon, 20 Jul 2026 00:00:00 -0400

arXiv:2607.14464v1 Announce Type: cross Abstract: We establish universal width predictions for near-threshold single-neutron resonances in $L > 0$ partial waves. Our results go beyond Wigner's well-known scaling behavior of cross sections near threshold. We show that the finite square-well potential exhibits discrete scale invariance at zero energy. From this fact, we derive an analytic baseline for the resonance width that depends only on geometry, angular momentum, and resonance energy, and not on internal short-distance nuclear details or radial excitation. This is a nontrivial property that is unique to the finite square-well potential and does not occur for other potentials. Application to observed p-wave and d-wave resonances demonstrates that the square-well result provides a robust baseline. We show that discrete scale invariance erases radial-node information in the sharp-boundary limit, but realistic Woods-Saxon diffuseness breaks this invariance, suppressing the reduced width by a factor sensitive to the internal radial excitation. These results provide a simple geometric benchmark for identifying when observed neutron resonances are controlled by universal threshold physics and when they exhibit systematic deviations driven by structure-dependent effects.

Causal Dynamic Resonance

Mon, 20 Jul 2026 00:00:00 -0400

arXiv:2508.16733v2 Announce Type: replace Abstract: Many dynamical systems in nature, such as brains and weather systems, are highly nonlinear and complex. Determining information flow among the components that make up these dynamical systems is challenging. If the components are the result of a common process or become synchronized, causality measures typically fail. We previously introduced Cross-Dynamical Delay Differential Analysis (CD-DDA), a nonlinear method for assessing causal influence, along with a complementary approach for dynamical similarity between time series data, Dynamical Ergodicity Delay Differential Analysis (DE-DDA). Here, we show that ``Causal Dynamic Resonance (CDR)'' further improves the false positive rejection rate by adding white noise to the data, without perturbing the underlying dynamical system. This is followed by a study of CDR in coupled R\"ossler systems, where ground truth interactions are known and in invasive intracranial electroencephalographic (iEEG) data from drug-resistant epilepsy patients undergoing presurgical monitoring.

Programmable Synchronization Graphs for Adaptive and Fault-Tolerant Modular Miniature Robots

Mon, 20 Jul 2026 00:00:00 -0400

arXiv:2607.07281v2 Announce Type: replace-cross Abstract: Modular miniature robots could provide scalable function in constrained environments, but coordinating many imperfect modules remains difficult when computation, communication and reliability are limited. A central robotics challenge is to coordinate many actuator-sensor modules without assigning a privileged leader, prescribing a fixed gait template, or relying on dense communication. Here we introduce a programmable synchronization-graph framework for modular miniature robots in which each actuator-sensor pair is represented as a network node and locomotor coordination is encoded through graph coupling. Fixed intra-subgraph links synchronize heterogeneous actuator groups, whereas a small number of signed inter-subgraph links program phase relationships between groups. In physical robot collectives with up to nine modules, graph coupling drives the emergence of synchronization, signed links tune the phase difference from in-phase to out-of-phase motion, and floor experiments produce gallop-like and trot-like contact patterns in a five-module robot assembly. Replacing dense all-to-all coupling with sparse d-regular topologies preserves synchronization while reducing the coupling burden. The same graph representation also captures fault tolerance: increasing graph degree increases the number of module deactivations tolerated before desynchronization. Finally, an upper-confidence-bound edge-selection algorithm learns inter-subgraph links that drive the system toward target phase states. In a separate deactivation benchmark, the graph-based controller avoids the leader-specific failure mode observed in centralized leader-follower control and reduces worst-case phase error by about threefold. These results establish programmable network topology as a compact control layer for gait phase programming, online adaptation and robustness to unit loss in modular miniature robots.

Criticality of nonreciprocal phase oscillators with long-range interactions

Mon, 20 Jul 2026 00:00:00 -0400

arXiv:2606.16427v2 Announce Type: replace Abstract: We study noisy identical Kuramoto-Sakaguchi oscillators with phase lag $\alpha\in[0,\pi/2)$, where $\alpha>0$ induces nonreciprocal interactions. Numerical phase diagrams in the $(\sigma, \alpha)$ plane in fully-connected graphs, formed by long-range weights tuned by $\sigma$ on $d$-dimensional lattices, reveal a critical phase lag $\alpha_c$, below which spontaneous synchronization occurs. This critical phase lag decreases monotonically with $\sigma$. We characterize the critical behavior analytically using the dynamical renormalization group theory.

Effect of the near-proton-emission threshold resonance in $^{11}$B on the branching ratio of beta-delayed proton emission from $^{11}$Be

Mon, 20 Jul 2026 00:00:00 -0400

Universal Properties of Near-Threshold Single-Neutron Resonances

Mon, 20 Jul 2026 00:00:00 -0400

Causal Dynamic Resonance

Mon, 20 Jul 2026 00:00:00 -0400

Programmable Synchronization Graphs for Adaptive and Fault-Tolerant Modular Miniature Robots

Mon, 20 Jul 2026 00:00:00 -0400

Criticality of nonreciprocal phase oscillators with long-range interactions

Mon, 20 Jul 2026 00:00:00 -0400

Bayesian Basin Tracking: Efficient Global Continuation of Multistable Dynamical Systems

Fri, 17 Jul 2026 00:00:00 -0400

arXiv:2607.14762v1 Announce Type: new Abstract: Mapping the global phase space of high-dimensional multistable dynamical systems is computationally prohibitive because conventional approaches require extensive numerical integration. Here, we introduce Bayesian Basin Tracking (BBT), an adaptive Bayesian framework that exploits the persistence of basin boundaries under parameter continuation to reconstruct global phase-space structure using only a fraction of the simulations required by conventional methods. By modeling the probability that a sampled initial condition converges to a particular attractor, the method represents the phase-space geometry established at a given parameter value through a Dirichlet-multinomial model. At a nearby parameter value, these probabilities are estimated by updating the prior distribution with newly sampled data. To detect boundary crises and bifurcations autonomously, we use the log Bayes factor as an information-theoretic sensor that triggers dense resampling only when structural changes render the historical prior statistically implausible. We validate the framework using the discrete H\'enon map, the continuous-time Duffing oscillator, and a 300-dimensional network of coupled R\"ossler oscillators. BBT overcomes the restrictive dimensional scaling of deterministic grid tessellations by concentrating the most computationally demanding calculations in structurally volatile regions. In high-dimensional synchronization landscapes, it achieves an almost sixfold computational speed-up while retaining theoretically derived error bounds.

Infectious Disease Induces Emergent Oscillations, Extinction and Changes in Community Persistence in a Food Chain

Fri, 17 Jul 2026 00:00:00 -0400

arXiv:2607.14360v1 Announce Type: cross Abstract: Food webs have been extensively studied from both ecological and mathematical aspects. However, most of the models studied in this area do not capture the effects of infectious diseases simultaneously. Recently, the idea of including an infectious disease in a food web model has been investigated. We study and simulate a small food chain consisting of only prey, predators, and apex predators governed by the generalized Lotka-Volterra equations, and we implement the Susceptible-Infected-Recovered (SIR) model on only one of the species at a time in the food chain. To study the effects of an infectious disease on the food chain, we introduce a new parameter that increases the predation rate by a factor of $w$ and decreases the hunting rate by a factor of $1/w$ for infected species. When the infectious disease is present in predators, we observe that predators do not become extinct under any set of parameters; however, an oscillation in their population size occurs under some circumstances, which we do not observe in ordinary SIR or the generalized Lotka-Volterra equations alone. When an infectious disease is present in apex predators, oscillations in the population size do not happen; but if the set of parameters is in a specific range the apex predators may become extinct. Furthermore, the chance of survival of the community, known as community persistence, increases for the predators and decreases for the apex predators.

Inferring Non-Normal Amplification Geometry from Multivariate Time Series

Fri, 17 Jul 2026 00:00:00 -0400

arXiv:2607.14786v1 Announce Type: cross Abstract: Across hydrodynamics, ecology, neuroscience, network dynamics, non-Hermitian physics, and socio-economic systems, asymptotically stable dynamics can exhibit large transient amplifications that are invisible to eigenvalue-based analyses. The mechanism is geometric rather than spectral: perturbations entering along one direction may be expressed transiently along another, allowing asymptotic decay to coexist with strong transient or noise-driven amplification. We introduce non-normal directional response inference, a data-driven method for detecting this geometry from multivariate time series when the governing operator is unknown. A local linear operator is estimated from sliding windows and projected onto the dominant two-dimensional input-response subspace. The reduced dynamics are summarized by the eigenvalue splitting $\Delta$, eigenvector non-orthogonality $K$, and the scale-free ratio $R=K/K_c(\Delta)$, where $K_c(\Delta)$ is the two-dimensional threshold for transient amplification. Controlled benchmarks show that the reduced geometry, particularly $R$, can be recovered from finite data even when the full high-dimensional operator is poorly estimated. Tests across sample size, dimension, training horizon, spectral structure, and non-stationarity confirm that the relevant response geometry requires far fewer observations than full-matrix recovery. Applied in moving windows to electrohysterogram, seizure EEG, freezing-of-gait, and unstable push-up inertial recordings, the method reveals systematic changes around known physiological or behavioral episodes through shifts in $R$, changes in $\Delta$, or stronger projection of fluctuations onto the inferred response direction. It thus exposes interpretable changes in local response geometry without framing the problem as supervised event detection.

Recurrence and anti-recurrence patterns reveal an antiperiodic fingerprint that survives into chaos in the Duffing--Holmes oscillator

Fri, 17 Jul 2026 00:00:00 -0400

arXiv:2607.05323v2 Announce Type: replace Abstract: The periodically forced Duffing--Holmes oscillator possesses a discrete symmetry under sign reversal of the coordinate combined with a half-period shift of the drive. When this symmetry is dynamically realized, the system supports \emph{antiperiodic} solutions, whose state at any instant is the point reflection of the state half a driving period earlier. We show that a standard recurrence plot (RP) is blind to this symmetry, whereas a complementary \emph{anti-recurrence plot} (anti-RP), built from the cross recurrence between a trajectory and its point-reflected image, detects it directly. Across four regimes -- periodic and chaotic single-well motion, and antiperiodic and chaotic two-well motion -- the anti-RP is empty when the attractor occupies one well and densely diagonal when the motion respects the symmetry. Crucially, the antiperiodic fingerprint persists into the chaotic two-well regime, where the anti-recurrence rate stays high relative to the ordinary one ($\mathrm{RR}_a/\mathrm{RR}\approx0.8$) despite the chaos. Recurrence quantification of both matrices separates order from chaos, while the anti-RP independently distinguishes one- from two-well, symmetry-respecting dynamics, giving a compact classification of all regimes. Requiring only a time series and the symmetry operation, the anti-RP is a model-free probe of dynamical symmetry for any system with a sign-reversal invariance, including experimental signals where phase-averaged observables fail.

Discrete-time maximally superintegrable systems and deformed symmetry algebras: the Calogero-Moser case

Fri, 17 Jul 2026 00:00:00 -0400

arXiv:2601.10625v2 Announce Type: replace-cross Abstract: We determine the complete structure of the symmetry algebras associated with the N-body Calogero-Moser system and its maximally superintegrable discretization. We prove that the discretization naturally leads to a nontrivial deformation of the continuous symmetry algebra, with the discretization parameter playing the r\^ole of a deformation parameter. This phenomenon illustrates how discrete superintegrable systems can be viewed as natural sources of deformed polynomial algebraic structures. As a byproduct of these results, we also reveal a connection between the above-mentioned symmetry algebras and the Bell polynomials, as a consequence of the trace properties.

Bayesian Inference for Extracting Barrier Distributions from Fusion Excitation Functions

Fri, 17 Jul 2026 00:00:00 -0400

arXiv:2607.14422v1 Announce Type: cross Abstract: Barrier distributions encode rich information about the structure and dynamics of fusing nuclei, but extracting them from experimental fusion cross sections requires an estimate of the fusion excitation function's second derivative. In this work we approach the task of extracting barrier distributions with uncertainty estimates from sparse experimental measurements as a Bayesian inference problem. We introduce a method based on AutoBNN, an interpretable Bayesian machine learning framework, to provide a robust statistical approach for analyzing fusion excitation functions. Benchmarking against Gaussian process regression on simulated excitation functions that span a wide range of realistic experimental conditions, we find that AutoBNN more faithfully recovers the underlying barrier distribution and reports well-calibrated uncertainties. We then apply the AutoBNN method to four experimentally measured heavy-ion fusion reactions where it mitigates spurious above-barrier structure and constrains existing predictions. Alongside these results, we have developed a user-friendly software implementation of our method, facilitating its application to future heavy and light-ion fusion experiments.

Impact of tensor-rank components of chiral three-nucleon forces on the single-particle structure of calcium isotopes

Fri, 17 Jul 2026 00:00:00 -0400

arXiv:2607.14458v1 Announce Type: cross Abstract: Background: Chiral three-nucleon forces (3NFs) play a key role in the microscopic description of nuclear shell evolution. A recent work introduced an irreducible tensor decomposition of the chiral 3NF at next-to-next-to-leading order and showed that, in $p$-shell nuclei, the enhancement of the $0p_{3/2}$--$0p_{1/2}$ spin--orbit (SO) splitting is mainly driven by its rank-1 component. Purpose: We extend the aforementioned analysis to the $0f1p$ shell to investigate whether the same mechanism persists in a heavier valence space, and how the different tensor-rank components of the 3NF affect structure properties of calcium isotopes. Methods: Effective shell-model Hamiltonians for neutrons outside the doubly magic $^{40}$Ca core are derived from chiral two-nucleon force plus 3NF. The latter is progressively included through its rank-$\lambda$ components ($\lambda=0,1,2,3$), allowing us to isolate their impact on the evolution of the neutron single-particle structure. Results: The significant enhancement of the SO splittings for both $1p$ and $0f$ orbitals produced by the chiral 3NF is mainly induced by its rank-1 component. The rank-2 term gives a smaller contribution, while the rank-3 term is negligible. The rank-0 component, and to a lesser extent the rank-1 component, are found to play an important role in determining the spacings between orbitals with different orbital angular momenta. All modifications induced by the 3NF in the single-particle structure have a relevant impact on the shell-closure properties of $^{48}$Ca. Conclusions: The dominance of the rank-1 two-pion-exchange component of the 3NF in explaining the enhancement of SO splitting -- previously identified in the $p$ shell -- persists in the $0f1p$ shell. Observed effects of the 3NF related to the different angular-momentum dependence of the orbitals are shown to arise essentially from their rank-0 and rank-1 components.

Node-locked phase of annual modulations from the gravitational chiral anomaly in the solar Kerr field

Fri, 17 Jul 2026 00:00:00 -0400

arXiv:2607.07912v2 Announce Type: replace-cross Abstract: The leading parity-odd mass--spin curvature invariant of the solar exterior, $P_{\odot}\equiv{}^{*}\!R\,R\simeq 288\,G^{2}M_{\odot}^{2}a_{\odot}\cos\theta/c^{4}r^{7}$, changes sign when the Earth crosses the solar equatorial plane and acts as the geometric source of the gravitational chiral anomaly. We study two minimal phenomenological responses to this structure: a long-memory reservoir $Q\propto\int(P_{\odot}-\langle P_{\odot}\rangle)\,dt$ and the local worldline derivative $D=u^{\mu}\nabla_{\mu}P_{\odot}$. Both have an annual Fourier phase fixed by ephemerides, $t^{*}=158.7$~d (June 7--8) or the opposite branch $t^{*}=341.4$~d, with a calculable secular drift of $+0.014$~d\,yr$^{-1}$ and an energy-independent geometric input phase, while predicting different semiannual fractions, $3.75\%$ and $15\%$, respectively. The response amplitudes and their microscopic origin are not predicted; the phase is. Single-amplitude fits to the digitized DAMA/LIBRA--phase2 1--3~keV residuals give $\chi^{2}/\mathrm{dof}=62.7/51$ for the reservoir and $63.6/51$ for the derivative, against $60.9/51$ for the standard-halo cosine. The most precise published phase, $t^{*}=153.5\pm3.8$~d, lies $0.3\sigma$ from the halo value and $1.4\sigma$ from the node-locked one; phase metrology at the two-day level ($\simeq3\sigma$), together with the phase-locked semiannual component, discriminates between the two clocks.

Ab initio calculations of two-neutrino and neutrinoless double-$\boldsymbol{\beta}$ decay of $^{48}$Ca and related Gamow-Teller strength distributions

Fri, 17 Jul 2026 00:00:00 -0400

arXiv:2607.11733v2 Announce Type: replace-cross Abstract: We present ab initio calculations of two-neutrino double-beta ($2\nu\beta\beta$) decay of $^{48}$Ca and the related Gamow-Teller (GT) strength functions in $^{48}$Sc using the valence-space in-medium similarity renormalization group (VS-IMSRG) with nuclear interactions and electroweak currents based on chiral effective field theory. We find that the usual $pf$-shell valence space significantly underestimates the nuclear matrix element (NME) of $2\nu\beta\beta$ decay compared to experiment, while an enlarged $d_{3/2}pf$ valence space yields very good agreement with the experimental value without any adjustments. We trace this to an improved description of the involved GT strength distributions, so that the enlarged valence space captures important correlations. The enlarged $d_{3/2}pf$ valence space leads to neutrinoless $\beta\beta$ NMEs of $^{48}$Ca that are twice as large compared to the $pf$-shell calculation. Our findings suggest that studies with different valence spaces and related GT strengths are important for assessing ab initio NME calculations of heavier $\beta\beta$ decays.

Quantum many-body mixed phase space revealed by hybrid feedback control

Fri, 17 Jul 2026 00:00:00 -0400

arXiv:2607.14223v1 Announce Type: cross Abstract: Understanding how complex systems transition between order and chaos is a central challenge of nonequilibrium physics. While weak perturbations of classical integrable systems give rise to a mixed phase space of coexisting regular and chaotic trajectories, analogous behavior in interacting quantum many-body systems has remained elusive. Here we develop and experimentally implement a hybrid quantum-classical feedback protocol that autonomously discovers and stabilizes long-lived regular trajectories in a superconducting quantum processor. Each iteration combines short-time quantum evolution with classical optimization that projects the dynamics back onto a low-entanglement variational manifold, effectively distilling coherence from chaotic evolution. The stabilized trajectories reveal a quantum many-body mixed phase space emerging from nonlinear variational dynamics, without a direct analogue in classical or few-body quantum systems. Our results establish a versatile framework for algorithmic discovery and control of coherent dynamics previously inaccessible to experiment.

Metamorphosis of transition between states of limit cycle oscillations in aeroacoustic system

Thu, 16 Jul 2026 00:00:00 -0400

arXiv:2607.13956v1 Announce Type: cross Abstract: Dynamical systems undergoing transition to oscillatory state exhibit change in the nature of the transition from supercritical to subcritical Hopf bifurcation or vice versa upon variation of a secondary parameter. This phenomenon is referred to as change of criticality. Many real-world systems undergo transition to oscillatory state that do not fit in the framework of Hopf bifurcation, and hence the change of criticality. We perform experiments on a ducted turbulent aeroacoustic flow constrained by two orifices separated at a distance apart. We vary the Reynolds number (Re), a bifurcation parameter causing a transition between various limit cycles. We change the distance between the orifices as the secondary parameter. We discover that turbulent aeroacoustic flows exhibit a metamorphosis of the transition from continuous to abrupt through a canard explosion, a bifurcation unique for its continuous yet rapid nature. We observe two distinct abrupt bifurcations, differing in their dynamical states associated with the transition. Understanding this metamorphosis from continuous to abrupt aids in developing low-cost control and preventive strategies for systems undergoing a route to oscillatory instabilities.

High-precision measurement of the kaonic hydrogen 1s level shift and width with SIDDHARTA-2

Thu, 16 Jul 2026 00:00:00 -0400

arXiv:2607.13952v1 Announce Type: new Abstract: Kaonic atoms provide a unique experimental probe of strong interaction in the low-energy regime. In particular, the strong-interaction-induced shift ($\varepsilon_{1\text{s}}$) and width ($\Gamma_{1\text{s}}$) of kaonic hydrogen directly constrain the low-energy antikaon-nucleon ($\bar{K}N$) interaction at threshold and the theoretical description of the $\Lambda$(1405) resonance. We report a new high-precision measurement of kaonic hydrogen X-ray transitions performed by the SIDDHARTA-2 experiment at the DA$\Phi$NE collider (INFN-LNF), based on an integrated luminosity of 237 pb$^{-1}$. The extracted values, $\varepsilon_{1\text{s}}\,=\,-303.0\,\pm\,17.0\,(stat.)\,\pm\,2.5\,(syst.)$ eV and $\Gamma_{1\text{s}}\,=\,607\,\pm\,62\,(stat.)\,\pm\,6\,(syst.)$ eV, represent the most precise determination to date, improving the precision by approximately a factor-of-two with respect to the previous SIDDHARTA measurement. These results significantly tighten the experimental constraints on theoretical description of the low-energy $\bar{K}N$ interaction.

Profile-Likelihood and Baseline-Sensitivity Diagnostics for Digitized Radiation-Sensor Decay Datasets

Thu, 16 Jul 2026 00:00:00 -0400

arXiv:2607.13118v1 Announce Type: cross Abstract: Accurate interpretation of radiation-sensor decay data is important for environmental monitoring, site remediation, radiation metrology, detector quality assurance, and nuclear data evaluation. When the original gamma-spectrometry records are unavailable, a published decay plot may be the only source that can be reanalyzed independently. This study presents a reproducible reduced-data workflow for testing half-life estimates from a digitized 198-Au decay dataset. A weighted exponential fit to the digitized data points reproduces the published room-temperature half-life, indicating that the main decay scale is retained in the figure-level dataset. The analysis then tests how the fitted result changes under plausible figure-level effects, including baseline-like offsets, time-axis reconstruction, finite-window leverage, and ratio-based robustness checks using pairwise summaries and Steiner's most frequent value statistics. The no-offset fit is locally well constrained, but small constant offsets can shift the fitted half-life because the normalization, decay constant, and residual baseline are partly degenerate over the limited time window. Toy Monte Carlo diagnostics show that some estimator shifts are expected for finite-window exponential data. This study does not revise recommended nuclear data or replace the original experiment. Instead, it shows how published radiation-sensor decay data can be tested for reproducibility, identifiability, and sensitivity to analysis choices when only reduced or figure-level information is available.

Characterisation of a Thick Pixelated Silicon Detector for Electron Spectroscopy of Neutron Beta Decay

Thu, 16 Jul 2026 00:00:00 -0400

arXiv:2607.13726v1 Announce Type: cross Abstract: Silicon detectors are commonly used for spectroscopy of low-energy particles. For electrons in the 1 MeV range, a rather large thickness of 2mm is required to entirely stop the electrons and commercial options are scarce. With the instrument PERC at the FRM II, we aim to measure beta spectra from polarised and unpolarised neutrons in order to determine the axial-vector coupling constant, the element $V_\textrm{ud}$ of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix, and to search for hypothetical scalar and tensor contributions. We present the characterisation of a commercially available, pixelated detector to assess its suitability to measure the entire electron energy spectrum of free neutron beta decay.

$\textit{Ab Initio}$ Exact Calculation of Strongly-Correlated Nucleonic Matter

Thu, 16 Jul 2026 00:00:00 -0400

arXiv:2508.09252v5 Announce Type: replace-cross Abstract: Dense nucleonic matter is of vital importance for understanding compact stars and inferring the transition into deconfined quark phase. We present $\textit{ab initio}$ exact calculations of infinite nucleonic matter with the state-of-the-art full configuration-interaction quantum Monte Carlo (FCIQMC) method, enabling us to rigorously benchmark many-body methods and assess the degree to which the nucleonic matter is correlated. Our method has been numerically validated against exact diagonalization within a small model space. Calculations of nucleonic matter using chiral nuclear forces reveal that symmetric nuclear matter is strikingly strongly correlated, raising questions on previous $\textit{ab initio}$ calculations of nuclear matter with many-body expansion truncations and offering insights into simultaneous descriptions of finite nuclei and infinite nucleonic matter from first principles.

Thermal and geometric normal modes of spectral fluctuations in heavy-ion collisions

Thu, 16 Jul 2026 00:00:00 -0400

arXiv:2604.26731v2 Announce Type: replace-cross Abstract: The transverse momentum spectrum of charged particles in ultra-relativistic heavy-ion collisions fluctuates event-by-event, encoding signatures of underlying collective dynamics. Such fluctuations originate from a combined effect of thermal and geometric fluctuations in the initial state. We present a direct decomposition of these spectral fluctuations through principal component analysis performed on the joint covariance structure of normalized spectrum, mean transverse momentum and elliptic flow squared. The first two leading modes explain 99.5\% of the total variance, and are orthogonally rotated by imposing physical constraints motivated by the initial state thermal and geometric response. The resulting thermal and geometric modes bear direct analogy with the vibrational normal modes of a linear triatomic molecule. The thermal mode entirely drives the experimentally measured $v_0(p_T)$, while the geometric mode contributes substantially to $v_{02}(p_T)$ in non-central collisions, providing a transparent explanation of its characteristic low-$p_T$ sign change. The study establishes the first physically motivated interpretation of principal component modes in the field of heavy-ion collisions and provides an experimental window into the thermo-geometric structure of the QGP initial state.

Lie Meets Network Dynamics: Exact Macroscopic Reductions (Finite Systems)

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2607.12210v1 Announce Type: cross Abstract: We establish a unified framework for exact dimensional reductions in network dynamical systems using Lie-Scheffers theory. For network dynamical systems with \emph{mean-field Lie-Scheffers structure}, we prove that networks of $n$ nodes with local dimension $d$ can be exactly reduced from $ n d $ dimensions to a fixed macroscopic system of dimension $ m d $, where $m$ is the number of fundamental solutions required by the nodal dynamics. Crucially, the superposition principle resulting from the Lie-algebraic structure allows the mean-field coupling to be expressed explicitly in terms of the macroscopic variables, yielding a \emph{closed} self-consistent system independent of network size. This reduction collapses the high-dimensional network flow onto invariant manifolds parameterized by $ \gamma = d(n-m) $ independent constants of motion. Our framework rigorously explains known reductions and provides a \emph{systematic method to discover new ones}. We illustrate the theory with ensembles of Riccati equations (encompassing the Kuramoto model and Theta neuron model), quasi-linear ODEs, and generalized Bernoulli equations, explicitly deriving the macroscopic flows and conserved quantities for each case.

Structured Fluctuations and the Information Dynamics of Self-Maintenance in Growing Neural Cellular Automata

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2607.12403v1 Announce Type: cross Abstract: Growing Neural Cellular Automata (GNCA) are capable of robust self-maintenance and self-repair, yet the internal dynamical mechanisms that support these capabilities remain poorly understood. Here, we investigate the role of internal fluctuations--temporal micro-variability of hidden channel states--in a trained GNCA model, challenging the assumption that such variability is merely residual stochastic noise. Through systematic analysis spanning update-rate sweeps, spatial correlation measurements, dimensionality reduction of collective state trajectories, localized damage experiments, transfer entropy vector field estimation, and partial information decomposition, we show that internal fluctuations are spatially structured, dynamically coupled to an attracting collective state, and associated with distributed small-magnitude updates that contribute to damage recovery. Damage induces a global deviation in latent state space followed by gradual re-convergence, and suppressing distributed small-magnitude updates associated with baseline fluctuation dynamics outside a permissive radius that encompasses the majority of the cells significantly impairs recovery. Transfer entropy analysis characterizes a spatially differentiated repair response: corrective inward flow near the damage site coexists with outward perturbation propagation at greater distances. Partial information decomposition further suggests a regime shift from synergy-dominant resting computation to redundancy-increased coordination during recovery. These findings indicate that GNCA self-repair emerges from high-dimensional nonlinear collective dynamics in which internal fluctuations serve as a functional component supporting information flow, coordination, and return toward an attracting recurrent state.

One Shot, Twenty-One Balls: Existence and Rarity of a Total Clearance in a Single Stroke of Snooker

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2607.12995v1 Announce Type: cross Abstract: Snooker folklore holds that no single stroke can pocket all twenty-one object balls. We examine the claim in an idealized but fully specified model of billiard dynamics. Within the model we exhibit an admissible configuration of the twenty-two balls and a stroke of the cue ball that pockets all twenty-one object balls, and we show that the set of such strokes has positive Lebesgue measure in the natural shot space: total clearances are not flukes of measure zero but open events. For the regulation opening configuration we conjecture the same and explain both why a simulation cannot settle the conjecture by brute force and what kind of computation could settle it in principle. Monte Carlo experiments in the same model estimate the probability P(k) that a uniformly random stroke pockets exactly k balls; the observed decay of P(k), extrapolated conditionally on the conjecture, places the probability of a total clearance from the break far beyond anything observable. The folk claim is thus right in practice and wrong in principle, and the gap between the two is exactly the distance between measure zero and unobservably small.

Operator theoretic causality analysis of fluid flows using linearized dynamics

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2506.08118v3 Announce Type: replace Abstract: This paper presents an operator-theoretic framework, Linear Operator Causality Analysis (LOCA), for analyzing causality in linearized dynamical systems, focusing here on fluid flows. Our proposed approach, which can be characterized as a special case of Dynamic Causal Effect (DCE) analysis, utilizes the matrix exponential of linearized differential equations to determine causal relationships between system modes at any future time. We further develop an upper bound that quantifies the presence and extent of global causality across all time horizons. This approach provides a physics-based alternative to data-driven statistical and information-theoretic causality measures such as Granger causality and transfer entropy. Unlike these data-driven techniques that infer causality from time-series data, LOCA leverages the linearized governing equations, yielding a physically-motivated and interpretable measure of causal interactions. We identify the conditions under which LOCA gives equivalent results to data-driven causality analysis methods, and further discuss connections to key system properties such as controllability, observability, and graph-theoretic transitive closure. To complement this operator-based approach, we introduce a data-driven methodology akin to Dynamic Mode Decomposition (DMD) that estimates causal connections directly from time series data by approximating the matrix exponential. We argue that LOCA also mitigates common issues in data-driven causality analyses, such as misleading inferences due to correlated variables or state truncation. We demonstrate our method on two fluid flow examples: linearized Couette flow, and a nonlinear wake flow featuring chaotic dynamics. In both cases, we demonstrate how our framework captures both direct and indirect causal interactions among flow structures.

Euler Ensemble as Decaying Turbulence Attractor: Universality, Stability and Parity Classes

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2607.05745v2 Announce Type: replace Abstract: We study local Lyapunov stability of the Euler ensemble in compact rescaled momentum-loop dynamics for freely decaying Navier-Stokes turbulence. The ensemble consists of exact self-similar finite-cutoff solutions whose momentum loops are equal-step polygons on a sphere; their planar representatives define the Euler ensemble. In two dimensions, after quotienting global rotation and the time-origin shift, the odd-$N$ planar representatives have no local shape instability. The even-$N$ ensemble contains an alternating unstable mode with $\lambda=\cot^2(\pi p/q)>0$, and is excluded as a local attractor. Thus the odd Euler ensemble is the locally stable planar sector. For $d>2$, the planar ensemble lies in a continuous manifold of equal-step spherical polygons. Transverse deformations along this manifold are exact tangent zero modes. Integrating over these unconstrained spherical modes in the continuum limit gives a singular Wilson-loop functional supported only on collapsed, globally rotated planar coordinate loops. These modes are therefore projected out of the admissible homogeneous isotropic ensemble. The physical stability problem is the decay of normal perturbations, represented by local edge-length defects. In the endpoint-local sector, the planar odd representative has exact defect spectrum $\lambda_m=-\sec^2(\pi m/N)<0$. In the smooth angular continuum limit, the leading stability operator is the universal angular Laplacian. Nearby spherical zero modes do not modify this leading operator; their first effect appears only at order $N^{-4}$, through higher-derivative corrections computed symbolically. Hence the leading local stability mechanism is universal and independent of spherical zero modes.

Riemann-Hilbert problem and long-time asymptotics of the Yajima-Oikawa equation

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2507.15645v2 Announce Type: replace Abstract: The Yajima-Oikawa equation is an integrable long wave-short wave resonance interaction model arising as a deformation of the Zakharov system for Langmuir waves coupled to ion-acoustic waves. In this work, a Riemann-Hilbert approach is developed for the Cauchy problem for the Yajima-Oikawa equation with rapidly decaying initial data. A main novelty is the formulation of a direct and inverse scattering theory adapted to its third-order spectral problem, including a detailed treatment of the singular spectral point $k=0$. The associated Riemann-Hilbert problem is expressed in terms of two reflection coefficients determined by the initial data, together with possible discrete eigenvalues and norming constants. We prove a vanishing lemma which ensures the unique solvability of the Riemann-Hilbert problem under suitable positivity assumptions, and hence obtain a rigorous reconstruction formula for the solution. We also classify the admissible discrete spectrum and derive exact pure soliton solutions from the reflectionless Riemann-Hilbert problem. In the solitonless case, we apply the Deift-Zhou nonlinear steepest descent method to obtain rigorous long-time asymptotic formulas in the different regions of the upper $(x,t)$-plane. The leading oscillatory behavior of the short-wave component is described explicitly in terms of the reflection coefficients evaluated at the stationary phase points, while the long-wave component is shown to be of lower order away from the transition region. These results provide, to the best of our knowledge, the first Riemann-Hilbert framework for the long-time asymptotic analysis of the Yajima-Oikawa equation in the presence of continuous spectrum.

ScatterPrism: convergence for generative simulation and inverse problems in particle and nuclear physics

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2604.01313v3 Announce Type: replace-cross Abstract: High-fidelity simulations and complex inverse problems, such as detector modeling and unfolding, are computationally intensive bottlenecks across subatomic physics, yet essential for accurate physical interpretation. While Conditional Flow Matching (CFM) offers a robust acceleration approach, we demonstrate its standard training loss is fundamentally misleading. Specifically, utilizing a Jefferson Lab Nuclear Physics (NP) kinematic dataset ($\gamma p \to \rho^0 p \to \pi^+\pi^- p$), we expose that CFM loss plateaus prematurely, obscuring ongoing physical refinement. To verify this disconnect is a dataset-agnostic pathology, we introduce ScatterPrism, an efficient generative surrogate evaluated against both the NP data and synthetic stress tests modeling challenging 1D distribution topologies. Coupling these benchmarks, we establish that physics-informed metrics continue improving long after standard loss converges. Consequently, we propose a multi-metric diagnostic protocol to ensure true kinematic fidelity without data memorization. Driven by NP challenges relevant to the forthcoming Electron-Ion Collider (EIC), this unified machinery has strong potential to extend to High-Energy Physics (HEP) applications, such as jet modeling. Furthermore, the framework holds promise for broader domains requiring rigorous generative reliability, including medical imaging, astrophysics, and quantitative finance.

Octupole deformation in even-even Ra isotopes from covariant density functional theory with localized exchange terms in a three-dimensional lattice space

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2607.12633v1 Announce Type: new Abstract: The covariant density functional theory in a three-dimensional lattice space is extended to the PCF-PK1 functional with localized exchange terms and is employed to study the nuclear shape evolution of even-even Ra isotopes. Well-developed axial octupole deformations are found for the ground states of $^{222-228}$Ra with no evidence of triaxial shapes. The energy gain of octupole deformation is employed to assess the stability of octupole deformation, with relatively larger values observed for $^{224}$Ra and $^{226}$Ra. A simplified analysis method based on the single-particle spectrum at the octupole deformation parameter $\beta_3=0$ is proposed to identify the key single-particle levels driving octupole deformation. It is found that the $m_z=3/2$ orbitals from $\nu 1j_{15/2}$ and $\nu 2g_{9/2}$ and the $m_z=1/2$ orbitals from $\pi 1i_{13/2}$ and $\pi 2f_{7/2}$, play crucial roles in the formation of octupole deformation in Ra isotopes. Furthermore, increasing the tensor coupling strength promotes octupole deformation, whereas reducing the pairing strength stabilizes it. Our results provide a microscopic understanding of octupole deformation in the Ra isotopic chain and highlight the importance of both tensor coupling and pairing correlations in reflection-asymmetric nuclear shapes.

Harmonic-dependent geometry-to-flow transfer in AMPT Ru+Ru and Zr+Zr isobar collisions

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2607.12660v1 Announce Type: new Abstract: We present a fixed-$N_{\rm part}$ study of geometry-to-flow transfer in string-melting AMPT simulations of $^{96}{\rm Ru}+^{96}{\rm Ru}$ and $^{96}{\rm Zr}+^{96}{\rm Zr}$ collisions at $\sqrt{s_{NN}}=200$ GeV. Four nuclear configurations are considered: deformation-only Ru+Ru, deformation-only Zr+Zr, deformation plus neutron skin Ru+Ru and deformation plus neutron skin Zr+Zr. The AMPT/HIJING initialization is modified to include deformed Woods--Saxon densities and, when enabled, separate proton and neutron Woods--Saxon radii and diffuseness parameters (neutron skin effect). We introduce an eccentricity-normalized isobar response double ratio, $D_n=(v_n^{\rm Ru}/v_n^{\rm Zr})/(\varepsilon_n^{\rm Ru}/\varepsilon_n^{\rm Zr})$, evaluated in common participant-number intervals. This observable eliminates the initial-geometry eccentricity ratio, and investigates whether the final-state flow ratio is fully determined by the initial-geometry ratio. We find that the elliptic double ratio is nearly unity, and the triangular double ratio is consistently greater than unity for the two deformation-only and deformation-plus-skin configurations. The positive $D_3-1$ pattern is maintained when varying the $N_{\rm part}$ binning, peripheral-bin treatment, flow $p_T$ range and rapidity/pseudorapidity acceptance. The result identifies a harmonic-dependent AMPT response: Ru/Zr elliptic flow follows leading eccentricity scaling to high accuracy, whereas triangular flow retains a residual response component after the triangularity ratio is divided out.

Role of the pre-equilibrium particle emission in the $^{249-251}$No production in the $^{204}$Pb($^{48}$Ca, xn)$^{252-x}$No reaction

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2607.12677v1 Announce Type: new Abstract: Experimental data on the production of the $^{250}$No isotope in an isomeric state in the $^{204}$Pb($^{48}$Ca, 2n)$^{250}$No reaction at $^{48}$Ca energies from 200 to 240 MeV are analyzed within a unified approach based on the Hauser-Feshbach model and Griffin's exciton model for the description of nuclear reactions, assuming one pre-equilibrium particle emission. Here, we study the effect of pre-equilibrium processes on the production of No isotopes. It is found that the regard for the pre-equilibrium emission of light particles essentially (few orders of the magnitude) enhance description of the experimental data on the No production cross sections, in particular, the production of $^{250g,m}$No in the ground and isomeric states. This allows one to reproduce the incident energy dependence of residual-nuclei production.

Three-dimensional, boost-invariant formalism for systems of relativistically moving constituents

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2607.12869v1 Announce Type: new Abstract: Light front quantum mechanics in three dimensions can be used to construct boost-invariant wave functions for the internal structure of relativistic systems. The Miller-Brodsky variable $\tilde{z}$ -- which is canonically conjugate to the momentum fraction $x$ -- allows a spatial description of the longitudinal degree of freedom. We show how $\tilde{z}$ can be constructed as an operator and prove its boost invariance. A relativistic harmonic oscillator potential from Li, Maris, Zhao and Vary [Phys Lett B 758 (2016) 118] is used as an example of a two-body interaction that can be constructed using $\tilde{z}$ and for which closed-form analytic solutions can be found. We systematically explore the conditions in which the non-relativistic harmonic oscillator solutions are reproduced and the conditions in which relativistic corrections are significant. Harmonic oscillator states are commonly used as a basis for nuclear many-body calculations. The present effort may provide a basis for providing light-front wave functions of nuclei.

Entangling Power and Symmetries in the Quantum Rabi Model

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2607.12053v1 Announce Type: cross Abstract: The quantum Rabi model is a standard effective Hamiltonian in studies of light-matter interaction, capturing the simplest nontrivial setting in which a qubit couples to a single harmonic oscillator. Within the broader Rabi family, we focus on two special cases: the Jaynes-Cummings (JC) model, which carries an explicit $U(1)$ symmetry, and the asymmetric quantum Rabi model (AQRM), which possesses a parameter-dependent "hidden'' symmetry that appears only at integer bias, $\varepsilon/\omega\in\mathbb{Z}$, and is not manifest in the Hamiltonian. We use the time-averaged entangling power as an operator-level diagnostic of these symmetry structures. Since the oscillator Hilbert space is infinite-dimensional, we compare two finite input ensembles: a Haar average after Fock-space truncation and a coherent-state average at fixed mean occupation $\bar{n}$. Both diagnostics show peaks at the integer-bias points of the AQRM, where the hidden symmetry resides. In contrast, the manifest $U(1)$ symmetry at the JC point instead gives a weak dip. Thus, the time-averaged entangling power responds to both the hidden symmetry and the $U(1)$ symmetry in the Rabi family, with the sign of the response indicating how the symmetry reorganizes the spectral expansion. These results demonstrate that the entangling power can serve as an operator diagnostic to reveal the presence and properties of hidden and manifest symmetries in light-matter systems.

Two-fluid $f$-mode oscillations of dark-matter-admixed neutron stars

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2607.12661v1 Announce Type: cross Abstract: We study quadrupolar $f$-mode oscillations of dark-matter-admixed neutron stars (DANSs) in full general relativity (GR). The ordinary component is described by microscopic Brueckner-Hartree-Fock matter matched to the Shen2020 crust, while the dark matter (DM) component is treated as a cold self-interacting fermion fluid coupled to ordinary matter only by gravity. For fixed-DM-fraction sequences we solve the polar two-fluid perturbation equations with an outgoing gravitational-wave (GW) boundary condition, obtaining complex eigenfrequencies rather than only real mode frequencies. The spectrum contains two principal $f$-like sequences. Their local character can be ordinary-matter-led, DM-led, or mixed, and is diagnosed using the component kinetic energies, the displacement overlap, and the cancellation of the matter quadrupole. A main result is that, for intermediate DM fractions, one of the two-fluid branches can become weakly radiating, with damping times enhanced by several orders of magnitude. The same calculation gives the outgoing Zerilli amplitude and the GW damping time, which we use to estimate the GW energy required to reach a prescribed detector threshold. Thus the analysis extends previous two-fluid Cowling studies by retaining metric perturbations and the radiative boundary condition.

The force of attraction between nucleons due to vacuum fluctuation

Wed, 15 Jul 2026 00:00:00 -0400

arXiv:2603.28379v2 Announce Type: replace-cross Abstract: We investigate quantum vacuum interactions arising from the zero-point fluctuations of a spatially confined massive scalar field. Deriving analytical expressions for the planar interaction energy and vacuum pressure, we identify a fundamental transition from the canonical power-law scaling of massless fields to a distinct quantum saturation regime. We prove that in the macroscopic limit, where the boundary separation far exceeds the field's Compton wavelength ($a \gg \lambda_c$), the interaction energy does not vanish; instead, it asymptotes to a persistent constant, $-\hbar c / (24\pi \lambda_c^3)$. This reveals a cohesive zero-point energy reservoir inherent to massive vacua. Applying this formalism to the femtometer scale of the deuteron ($^2$H) nuclei, we demonstrate that confining massive pion fluctuations generates an attractive force between nucleons.

Higher-order interactions for controlling time-delayed Kuramoto model

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.10759v1 Announce Type: new Abstract: We propose a framework for controlling the collective dynamics of the time-delayed Kuramoto model based on a delay-free, higher-order approximation of the delayed interactions. By applying the Ott--Antonsen ansatz and the second-order averaging method to the resulting higher-order Kuramoto model, we obtain a one-dimensional reduced equation for the order parameter dynamics. Numerical simulations demonstrate that the higher-order approximation predicts the dynamics of the original delayed system more accurately than the conventional pairwise approximation and enables the realization of bistability and intermediate synchronization states. Our results demonstrate the effectiveness of higher-order interpretations of time delays for the control of oscillator networks with time-delayed interactions.

Revisiting the non-equilibrium phase transitions of the continuous-trait Axelrod model

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.10381v1 Announce Type: cross Abstract: We investigate the non-equilibrium phase transitions of the continuous-trait Axelrod model, an agent-based framework where individual culture is represented by a vector of $F$ continuous features confined to the interval $(0,1)$. Local interactions are governed by a metric similarity threshold $d$, which acts as a continuous control parameter of social tolerance. The dynamics inevitably freeze into one of two absorbing configuration classes: an ordered, homogeneous monocultural state at high tolerance, or a highly fragmented, disordered state at low tolerance. While previous studies characterized the transition as hybrid based on the continuous behavior of the domain density $\mu$ alongside a discontinuous jump in the largest domain fraction $\rho$, we show that this apparent continuity is an artifact of severe finite-size masking effects. By shifting the methodological focus to the scaling of the median $\tilde{\mu}$ and analyzing the full probability distributions $P(\mu)$, we unveil a clear bimodal structure with disjoint maxima across independent simulation runs. Our results reveal that for $F=2$, the system undergoes a genuinely hybrid transition in the contemporary sense, featuring a tiny but finite latent jump ($\mu_c \approx 0.089$) at the critical threshold $d_c \approx 0.0784$ while scaling toward it from below via a non-analytical power law with a mean-field exponent $\beta \approx 1/2$. Conversely, for $F=3$, the higher trait-space dimensionality suppresses local fluctuations, yielding a traditional, non-hybrid first-order transition. We apply this framework to the alternative discrete Poisson variant of the model, successfully confirming its known continuous transition for $F=2$ and discontinuous, non-hybrid transition for $F=3$, thereby establishing a unified characterization of phase transitions in Axelrod-like systems.

Coherence as Thermodynamic Organization: Toward a Non-Equilibrium Turbulence Theory

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.11817v1 Announce Type: cross Abstract: Since the foundational studies in the late nineteenth century, fluid turbulence has stood as a profound, unsolved challenge in classical physics. Much of this enduring difficulty stems from non-equilibrium turbulence, where the lack of a unifying physical framework for macroscopic coherent structures has hampered predictive flow modeling. Here, we establish a foundational bridge between non-equilibrium statistical physics and turbulent coherent structures through the renormalized Navier-Stokes equations. We demonstrate that all forms of turbulent coherence are fundamentally universal thermodynamic responses mandated by macroscopic energy throughput imbalances. Depending on topological access to bifurcations, these formations manifest either as transient adjustments (analogous to Kubo's near-equilibrium fluctuations) or as autonomous, transformative states (mirroring Prigogine's far-from-equilibrium dissipative structures). By introducing a computable, effective thermodynamic order parameter ($\Pi$), this paradigm establishes a rigorous foundation for non-equilibrium theory, enabling unequivocal identification of necessary flow resolution in continuously driven, dissipative continuum systems.

Passive two-plateau relaxation from Tricomi confluent hypergeometric kernels

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2604.11464v2 Announce Type: replace-cross Abstract: Anomalous relaxation with memory spectra arises in disordered solids, soft matter, biological tissues and electrochemical interfaces. Fractional-order models capture broad power-law behaviour efficiently, but they can obscure spectral structure and are not always convenient for passive realisation or finite-dimensional simulation. We introduce a non-fractional passive framework based on the Tricomi confluent hypergeometric function, combined with a bounded Moebius normalisation that enforces prescribed low-frequency and high-frequency plateaux while preserving a broad dispersive transition. The resulting family contains the Debye and Cole-Cole responses as exact subcases, while extending them to asymmetric two-plateau dispersive laws with independently tunable low- and high-frequency exponents. For an admissible parameter range, we prove that the bounded block admits a Stieltjes representation with nonnegative spectral density, implying complete monotonicity, passivity, causality and compatibility with standard circuit and state-space descriptions. Building on this structure, we derive a passive Gauss-Stieltjes discretisation leading to Foster-type rational approximations and first-order state-space realisations with positive poles and residues. Numerical experiments show convergence of these finite-dimensional approximations across moderate-memory and long-tail regimes, enabling passive reduced-order representations of broad-memory responses. The framework is then validated on broadband dielectric data and battery electrochemical impedance spectra. In tissues, multi-block Tricomi mixtures improve complex-domain fitting accuracy relative to classical Cole-Cole baselines while preserving interpretable modal structure.

A Minimal Active-Particle Realization of Non-Hermitian Chern Bulk-Boundary Correspondence

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2606.24926v2 Announce Type: replace-cross Abstract: We show that a minimal frustrated Vicsek--Kuramoto active-particle model realizes a non-Hermitian Chern bulk-boundary correspondence. Unlike previous field-level settings, the Chern structure here emerges from microscopic self-propelled particles with a Sakaguchi phase lag. Fourier truncation of the phase distribution gives a non-Hermitian hydrodynamic matrix whose isotropic spectrum compactifies the wave-number plane; away from singular phase-lag endpoints, the frustration parameter twists endpoint eigenvectors and generates nontrivial Chern sectors. Nonlinear saturation then makes the selected spectral flow visible under collision boundaries, where strip modes predict chiral edge transport in agreement with particle simulations.

Microscopic Variability Alters Macroscopic Rotation Speed in Stochastic Spiral Waves

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2511.21710v3 Announce Type: replace Abstract: We present a general theory for noise-induced corrections to the angular velocity of spiral waves. Stochasticity produces two second-order effects: an instantaneous term from heterogeneity that always slows rotation, and an orbital-drift term from temporal fluctuations that can either accelerate or decelerate it. For our parameters, orbital drift is weaker, producing a net slowdown. Analytical predictions match Barkley-model simulations with temporal noise. Examination of additional noise types in silico confirms angular velocity slowing. This mechanism provides a robust route by which stochasticity reshapes spiral dynamics in excitable media, with direct implications for arrhythmias and neural wave propagation.

Resonance phenomena in vortex-antivortex collisions

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2510.17964v2 Announce Type: replace-cross Abstract: In this work, we provide a full map of scattering scenarios between a Nielsen-Olesen vortex and antivortex. Importantly, in the deep type II regime, such a collision reveals a chaotic pattern in the final state formation with bounce windows immersed into annihilation regions. This structure is due to the energy transfer mechanism triggered by a quasinormal mode, specifically the Feshbach resonant mode, hosted by the vortex.

On the discrete Painlev\'e equivalence problem, non-conjugate translations and nodal curves

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2604.13782v2 Announce Type: replace Abstract: We consider several examples of nonautonomous systems of difference equations coming from semi-classical orthogonal polynomials via recurrence coefficients and ladder operators, with respect to various generalisations of Laguerre and Meixner weights. We identify these as discrete Painlev\'e equations and establish their types in the Sakai classification scheme in terms of the associated rational surfaces. In particular, we find examples which come from different weights and share a common surface type $D_5^{(1)}$ but are inequivalent in two ways. First, their dynamics are generated by non-conjugate elements of $\widehat{W}(A_3^{(1)})$. Second, some of the examples have associated surfaces being non-generic in the sense of having nodal curves. The symmetries of these examples form subgroups of the generic symmetry group, which we compute. In particular, we find $(W(A_1^{(1)})\times W(A_1^{(1)}))\rtimes \mathbb{Z}/2\mathbb{Z}$. These examples give further weight to the argument that any correspondence between different weights and the Sakai classification should make use of the refined version of the discrete Painlev\'e equivalence problem, which takes into account not just surface type, but also the group elements generating the dynamics as well as parameter constraints, e.g. those corresponding to nodal curves.

Pole Dynamics, Linearization, and Perturbations of the Satsuma--Mimura Equation

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2606.16789v2 Announce Type: replace Abstract: This paper investigates the pole dynamics and perturbation theory of algebraic soliton solutions associated with the Satsuma--Mimura (SM) equation. First, we give a qualitative analysis of the pole system associated with algebraic soliton solutions, thereby completing a point left open in \cite{Yan_2025}. We then examine three perturbations of the SM equation. The $u_x$ perturbation preserves exact linearizability and leads to an explicit shifted algebraic soliton solution. The $u_{xx}$ perturbation can be reduced to the unperturbed SM equation by a scaling transformation, which yields the corresponding pole asymptotics and soliton profile. For the genuinely nontrivial $Hu_{xx}$ perturbation, we derive the first-order perturbation equations and present a short-time numerical simulation based on an explicit Euler discretization. These results clarify how algebraic solitons of the SM equation respond to different perturbative mechanisms.

Discrete Gerdjikov-Ivanov models and their higher-order counterparts from the Cauchy matrix scheme

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.09333v2 Announce Type: replace Abstract: The Gerdjikov-Ivanov (GI) equation is an important model in the derivative nonlinear Schrodinger system, yet its fully discrete integrable analogues remain unexplored. In this paper, we systematically construct discrete versions of both the GI equation and its higher-order counterpart (hGI equation) within the Cauchy matrix framework. Starting from the Sylvester equation equipped with two distinct sets of discrete dispersion relations, we derive the shift dynamics of the master functions and eliminate auxiliary variables to obtain closed lattice systems. Since the elimination step admits several equally valid algebraic identities, this procedure yields four conjugate-symmetric families of discrete GI (dGI) models and four families of discrete higher-order GI (dhGI) models. For each discrete model, we provide explicit N-soliton and multiple-pole solutions via the Cauchy matrix method with diagonal and Jordan-block spectral matrices, respectively. We verify through a two-step continuum limit, contracting one lattice direction at a time, that all four dGI models reduce to the same continuous GI equation and all four dhGI models reduce to the same continuous hGI equation. Finally, we investigate reductions: local complex conjugate reductions yield scalar dGI and dhGI equations with explicit solutions. Moreover, in the higher-order case, pairwise recombinations of the dhGI lattice equations admit nonlocal reductions that produce nonlocal dhGI equations and their solutions.

On the integrability structure of the deformed rule-54 reversible cellular automaton

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2603.25424v3 Announce Type: replace-cross Abstract: We study quantum and stochastic deformations of the rule-54 reversible cellular automaton (RCA54) on a 1+1-dimensional spatiotemporal lattice, focusing on their integrability structures in two distinct settings. First, for the quantum deformation, which turns the model into an interaction-round-a-face brickwork quantum circuit (either on an infinite lattice or with periodic boundary conditions), we show that the shortest-range nontrivial conserved charge commuting with the discrete-time evolution operator has a density supported on six consecutive sites. By constructing the corresponding range-6 Lax operator, we prove that this charge belongs to an infinite tower of mutually commuting conserved charges generated by higher-order logarithmic derivatives of the transfer matrix. With the aid of an intertwining operator, we further prove that the transfer matrix commutes with the discrete-time evolution operator. Second, for the stochastic deformation, which renders the model into a Markov-chain circuit, we investigate open boundary conditions that couple the system at its edges to stochastic reservoirs. In this setting, we explicitly construct the non-equilibrium steady state (NESS) by means of a staggered patch matrix ansatz, a hybrid construction combining the previously used commutative patch-state ansatz for the undeformed RCA54 with the matrix-product ansatz. Finally, we propose a simple empirical criterion for detecting integrability or exact solvability in a given model setup, introducing the notion of digit complexity.

2D inviscid Boussinesq equations and 3D axisymmetric Euler equations: (1) A unification ($Em$), (2) Finite-time blow-up of two unified $(1+1)$D systems rigorously derived from ($Em$)

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2603.26715v5 Announce Type: replace-cross Abstract: We derive a unified polar $(1+2)$D subsystem $(Em)$, with $m=1,2$, from the 2D inviscid Boussinesq and 3D axisymmetric Euler equations. On the symmetry axes $\theta=0,\pm\pi/2,\pi$, ridge flatness closes the dynamics and gives two exact unified $(1+1)$D reductions: the horizontal-axis system $(R0)$ and the vertical-axis system $(Z0)$. Their common apex trace is a Constantin--Lax--Majda type ODE that yields finite-time blow-up at $x=0$. Subsection~\ref{seq:vorticity-strain} connects this pointwise mechanism with Euler continuation theory: for any compatible axisymmetric realization, explicit apex blow-up forces divergence of the time-integrated $L^\infty$ norm of $\nabla\boldsymbol v$, so the singularity is detected by the strain criterion. Section~\ref{sec:R0-SS} strengthens the reduced mechanism by constructing regular apex-only self-similar profiles for the convective horizontal-axis equation $(R0)$; the resulting solution is bounded away from $x=0$, blows up at the apex, and satisfies the same strain-divergence condition. Finally, we derive the exact background--remainder equations and state a conditional nonlinear stability framework: if a compatible full background, weighted elliptic/coercive estimates, and a spectral gap exponent are available, then the apex blow-up transfers to the full solution. Thus the rigorous components are the derivation of $(Em)$, $(R0)$, and $(Z0)$, the apex blow-up and strain verification, the apex-only $(R0)$ self-similar construction, and the perturbative framework; the remaining open step is the unconditional construction and control of the full background away from the apex.

Precision masses of neutron-rich platinum and gold nuclei reveal enhanced $N=126$ shell strength below doubly-magic $^{208}$Pb

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.10894v1 Announce Type: new Abstract: The heaviest stable nuclei in the universe owe their existence to quantum shell structure, the grouping of protons and neutrons into discrete energy levels separated by gaps. The largest known neutron shell gap in stable nuclei, at $N=126$, stabilizes doubly-magic $^{208}$Pb and is responsible for the characteristic abundance peak of heavy elements near gold and platinum produced by the rapid neutron-capture process (r-process). Whether this shell gap persists as protons are removed from lead is a question central to both nuclear structure and the modeling of heavy-element synthesis, yet it has remained unanswered due to the extraordinary difficulty of producing the relevant neutron-rich nuclei. Direct experimental knowledge in this region was essentially absent. Here we report the first precision mass measurements of $^{203,204}$Pt and $^{204,205,206}$Au, performed at GSI using a novel combination of Schottky and isochronous mass spectrometry in a heavy-ion storage ring. The $N=126$ isotones $^{204}$Pt and $^{205}$Au are more strongly bound than the extrapolated trend of the previously known mass surface by 403 and 464~keV, respectively, revealing an unexpectedly enhanced $N=126$ shell strength below doubly-magic $^{208}$Pb. Furthermore, the proton-neutron interaction strength exhibits a hitherto unobserved bifurcation at $N=126$ as protons are removed from $^{208}$Pb. Our results redefine the nuclear mass surface in the neutron-rich heavy-element region and provide direct experimental benchmarks for theoretical models whose extrapolations toward more exotic nuclei are essential for r-process nucleosynthesis calculations.

Observation of the centrality-dependent difference in directed flow between charged kaons and $K^{*0}$ resonances in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 14.6, 19.6 and 27 GeV

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.11191v1 Announce Type: new Abstract: We present the measurement of rapidity-odd directed flow ($v_{1}^{\mathrm{odd}}$) for charged kaons, $\phi$ mesons, and $K^{*0}(\overline{K^{*0}})$ resonances in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 14.6, 19.6 and 27 GeV. This study includes the first measurement of the $K^{*0}$ resonance $v_{1}^{\mathrm{odd}}$ in heavy-ion collisions. Our measurement shows a centrality-dependent difference in directed flow between charged kaons and $K^{*0}$ resonances, which becomes more pronounced with increasing collision centrality. In contrast, the difference in directed flow between charged kaons and $\phi$ mesons remains nearly independent of centrality. Although anisotropic flow is thought to be developed in the early stages of the collision, for short-lived resonances such as the $K^{*}(892)$ that experience substantial hadronic re-scattering, it remains unclear to what extent the observed $v_{1}^{\mathrm{odd}}$ reflects genuine partonic collectivity in the early stage, and to what extent it is altered by late-stage hadronic interactions and/or reconstruction effects. The present measurement is crucial for disentangling these contributions and addressing this question. Existing hydrodynamic calculations that include a hadronic afterburner based on the UrQMD model indicate that an asymmetric modification of the $K^{*0}$ yield, due to rescattering, relative to the first-order event plane is required to reproduce the observed difference between $v_{1}^{\mathrm{odd}}$ for charged kaons and $K^{*0}$.

Structure of even-even Zr isotopes with 52$\leq$N$\leq$58 neutrons

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.11409v1 Announce Type: new Abstract: Excited levels in $^{92}$Zr have been studied in cold-neutron capture reaction using the EXILL Ge array at ILL Grenoble. Excited levels in $^{94}$Zr and $^{98}$Zr nuclei have been studied using high-statistics $\gamma$-coincidence data from neutron-induced fission of $^{235}$U measured with EXILL. The goal of was to search for new levels in $^{92,94,98}$Zr and to improve spin-parity assignments to excited levels. Total of 54 new levels, 180 new $\gamma$ transitions and 70 new or improved spin-parity assignments have been determined in the three isotopes in the present work. A precise neutron binding energy of 8634.81(2) keV has been determined in $^{92}$Zr. In $^{94}$Zr a Gamow-Teller transition is proposed. The (9$^-$), 3894.1-keV level in $^{98}$Zr is likely a few ns isomer. A new technique of estimating half-lives in a picosecond range, developed in this work, provided 61 half-lives and 60 B($\pi ,\lambda$) rates for transitions in $^{96,98}$Zr and $^{94,96}$Sr. New-type systematics, backed by Large Scale Shell Model calculations have been used to classify 2$^+$ excitations in Zn-Zr even-even nuclei of the 50$\le$N$\le$60 range. This information and new systematics of 0$^+$ excitations in Sr and Zr isotopes explain the evolution of collectivity in zirconium isotopes, showing the role of various single particle excitations in the phase transition and coexistence of the region. The role of the $\nu$9/2$^+$[404] extruder orbital as a catalyst in creating 0$^+$ excitations and the deformation change in the region has been discussed.

Experimental Review on Bulk Properties and Light/Strange Hadron Production in Heavy-Ion Collisions

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.11640v1 Announce Type: new Abstract: This proceedings article reviews recent experimental results on bulk properties and light/strange hadron production in heavy-ion collisions, presented at the Strangeness in Quark Matter 2026 conference. The discussion covers the QCD phase diagram, extraction of the temperature-dependent speed of sound, radial flow fluctuations probed by $v_0(p_T)$, anisotropic flow in small collision systems, strange hadron yields across system sizes, nuclear modification factors, and collectivity signatures at high baryon density. Results from the STAR, CMS, ALICE, ATLAS, PHENIX, NA61/SHINE, and HADES collaborations are synthesized to highlight recent progress in understanding the properties of the Quark-Gluon Plasma and the nature of the QCD phase transition.

Absence of a shell closure in $^{140}$Sn

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.09897v1 Announce Type: cross Abstract: There are conflicting theoretical results about the presence of a shell closure in the neutron-rich nucleus $^{140}$Sn. We address this controversy by performing ab initio computations, using a nuclear interaction from chiral effective field theory that accurately reproduced and predicted low-lying states in doubly magic nuclei. We verify that this interaction accurately reproduces low-lying states in $^{133}$Sn. We assume that $^{140}$Sn exhibits a closed $7/2^-$ neutron subshell beyond $^{132}$Sn and compute its first excited $2^+$ state. The resulting energy is small and this contradicts the assumption.

A Lawson-inspired Cycle-Closure Criterion for Deuterium--Tritium Muon-Catalyzed Fusion

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.10989v1 Announce Type: cross Abstract: Deuterium--tritium muon-catalyzed fusion is limited by a cycle-closure problem: a negative muon must complete enough catalytic cycles before decay or effective alpha sticking removes it from reuse. We formulate a Lawson-inspired criterion for this single-muon cycle. The effective cycle strength is defined as $\mathcal{L}_\mu=\Lambda_c\tau_\mu$, where $\Lambda_c$ is the effective cycle-completion rate and $\tau_\mu$ is the muon lifetime. Together with the residual effective sticking probability $\omega_S^{\rm eff}$, it gives the mean fusion yield per useful muon, $N_{\rm fus,\mu}=\mathcal{L}_\mu/(1+\omega_S^{\rm eff}\mathcal{L}_\mu)$. Introducing the useful D--T cycle energy $E_{\rm use}$, the system factor $\eta_{\rm sys}$, and the effective muon cost $E_\mu^{\rm cost}$, the one-muon gain is $G_\mu=(\eta_{\rm sys}E_{\rm use}/E_\mu^{\rm cost})N_{\rm fus,\mu}$. This leads to the required cycle strength $\mathcal{L}_\mu^{\rm req}=G_\mu N_L/(1-\omega_S^{\rm eff}G_\mu N_L)$, with $N_L=E_\mu^{\rm cost}/(\eta_{\rm sys}E_{\rm use})$, and to the conditional sticking boundary $\omega_S^{\rm eff}<1/(G_\mu N_L)$. The criterion separates rate-limited, sticking-limited, and cost-limited regimes in the $(\omega_S^{\rm eff},\mathcal{L}_\mu)$ plane. When representative historical D--T $\mu{\rm CF}$ anchors are projected onto this plane, they lie in a high-yield region but remain constrained by the effective-sticking boundary under conventional multi-GeV muon-cost accounting. The framework provides a compact diagnostic for assessing whether future improvements act mainly by increasing the effective cycle-completion rate, reducing residual sticking, or lowering the useful cost of delivered muons.

Ab initio study of $\beta$-decay and pairing in $N=Z$ nuclei

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2607.11452v1 Announce Type: cross Abstract: We investigate the $\beta$-decay properties of $rp$-process waiting-point nuclei $^{72}$Kr, $^{68}$Se, and $^{64}$Ge from realistic nuclear forces based on chiral effective field theory. The \textit{ab initio} valence-space in-medium similarity renormalization group method is employed for this purpose to consistently derive Hamiltonians and Gamow-Teller operators from chiral two- and three-nucleon interactions. The calculated half-lives and branching ratios indicate that nearly the entire decay intensity is confined within 1 MeV of excitation energy in the daughter nuclei. We address the isoscalar and isovector pairing and their impact on ground state properties of these waiting-point nuclei, along with several other $N=Z$ systems in the $fp$-shell. Our results do not provide evidence for an isoscalar condensate or any dominant isovector pairing condensate-like phase in these $N=Z$ nuclei. We present the full $B(\mathrm{GT})$ strength distributions and discuss the influence of pairing correlations on them. The present work provides a microscopic picture of $\beta$-decay strengths and pairing in $N=Z$ nuclei far from the stability line.

Evidence for a $\bar{K}NN$ quasi-bound state in the $\gamma d \to K^0\Lambda p$ reaction

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2606.16258v2 Announce Type: replace Abstract: The $\gamma d \to K^{0}\Lambda p$ reaction has been studied to search for a $\bar{K}NN$ quasi-bound state using the LEPS2 solenoid spectrometer at SPring-8. A localized enhancement concentrated at low $q$ is observed in the $(M_{\Lambda p},q)$ distribution below the $K^-pp$ mass threshold, where $M_{\Lambda p}$ is the $\Lambda p$ invariant mass and $q \equiv |\vec{p}_{\gamma}-\vec{p}_{K^{0}}| = |\vec{p}_{\Lambda p}|$ is the momentum transfer. A two-dimensional $(M_{\Lambda p},q)$ fit demonstrates that the enhancement near the threshold is statistically significant, yielding a local significance of $7.3,\sigma$. The enhancement is characterized by effective shape parameters including the Breit--Wigner mass $M$ and width $\Gamma$, and a Gaussian form-factor momentum scale $Q$: $M = 2.354 \pm 0.011(\mathrm{stat.})^{+0.009}_{-0.005}(\mathrm{syst.})~\mathrm{GeV}/c^{2}$, $\Gamma = 0.055 \pm 0.023(\mathrm{stat.})^{+0.031}_{-0.009}(\mathrm{syst.})~\mathrm{GeV}/c^{2}$, and $Q = 0.350 \pm 0.041(\mathrm{stat.})^{+0.035}_{-0.010}(\mathrm{syst.})~\mathrm{GeV}/c$. The obtained results support the existence of a $\bar{K}NN$ quasi-bound state in photoproduction.

Constraining the nuclear symmetry energy with electric dipole polarizability and neutron skin characteristics in \texorpdfstring{$^{208}\mathrm{Pb}$}{208Pb} within antisymmetrized molecular dynamics

Tue, 14 Jul 2026 00:00:00 -0400

arXiv:2602.19039v2 Announce Type: replace-cross Abstract: The electric dipole polarizability $\alpha_D$ and the neutron-skin thickness $\Delta R_{np}$ of $^{208}\mathrm{Pb}$ are two powerful and clean probes for constraining the symmetry energy at subsaturation densities. Within the framework of the antisymmetrized molecular dynamics (AMD) model, the width of the strength function and its dynamical origins are understood, and the $\alpha_D$ and $\Delta R_{np}$ data favor effective interaction parameter sets with $S_0\approx32$-34 MeV and $L=64$-87 MeV. In addition, our calculations show that the sensitive densities of $\alpha_D$ and $\Delta R_{np}$ range from 0.2$\rho_0$ to 0.57$\rho_0$, and the corresponding values of the symmetry energy at the lower and upper ends of this sensitive density region are $S(0.2\rho_0)=10.18\pm 1.10$ MeV and $S(0.57\rho_0)=22.31\pm 1.32$ MeV.

Stabilization of two-dimensional optical continuous-wave states by a potential trough

Mon, 13 Jul 2026 00:00:00 -0400

arXiv:2607.09607v1 Announce Type: new Abstract: We consider quasi-one-dimensional (Q1D) continuous waves (CWs) in the two-dimensional (2D) optical system with the cubic-quintic nonlinearity and a Q1D potential trough. In the case of a smooth trough profile, we confirm the known modulational instability (MI) of Q1D CWs with the transverse structure corresponding to the 1D ground state (GS) in the potential trough, and demonstrate the MI of CWs with the dipole-mode (DM) transverse structure, corresponding to the lowest 1D excited state in the potential trough. The CWs of both GS and DM types remain nearly stable close to the edges of their existence regions. Stable stationary states in the form of periodic chains of 2D solitons, trapped in the potential trough, are produced in a numerical form. The dynamics of the soliton chains excited by a localized kick is studied too. For the potential trough with the singular delta-functional profile, we find two species of exact analytical solutions for CWs, one of which is completely stable.

Superheavy dark-bright soliton as a signature of spatial symmetry breaking transition in harmonically trapped Bose mixtures

Mon, 13 Jul 2026 00:00:00 -0400

arXiv:2607.09064v1 Announce Type: cross Abstract: We investigate the dynamics of a dark-bright soliton in harmonically trapped two-component Bose-Einstein condensates and reveal an interesting spontaneous spatial symmetry breaking driven by nonlinear interactions. When the interaction parameter crosses a threshold value, we find that the dark-bright soliton's motion demonstrates a transition from symmetric periodic oscillation about the origin to asymmetric oscillations offset from the origin. In particular, at the transition point, the effective soliton mass, determined by the ratio of inertial mass to physical mass, diverges. The underlying mechanism is uncovered by constructing trial wave functions and employing the Lagrangian variational method to obtain an effective potential in the quasiparticle picture, which changes from a single well to a double well. The anomalous ``superheavy soliton'' phenomenon is a direct consequence of the dark-bright soliton's physical mass vanishing at the transition point. We obtain the phase diagram of this spatial symmetry-breaking transition. Possible implications of our finding for quantum metrology are discussed.

Field observation of soliton gases in the deep open ocean

Mon, 13 Jul 2026 00:00:00 -0400

arXiv:2510.04662v2 Announce Type: replace Abstract: Soliton gases are large ensembles of random solitons with distinct characteristics arising from integrable system dynamics. They have been widely studied in theory and experiments, and were observed in natural lagoons. However, it remains an open question whether they occur naturally in the open ocean. Nonlinear ocean states containing solitons have been observed in the literature, but the dominance of solitons over other wave components required for a soliton gas has not been demonstrated. Our study provides the first field evidence of soliton gas sea states in the deep ocean, measured in Taiwan waters. The soliton energy ratio derived from the nonlinear Fourier transform (NFT) is used as a key parameter to quantify how close sea states are to soliton gases. We identify eleven measurements with extremely high soliton energy ratios. They are characterized by short-period waves with relatively small wave heights, accompanied by extreme steepness and Benjamin Feir Index (BFI) values. These states are exceptionally rare, representing only 0.054\% of our dataset. Since directional interference can artificially increase the estimated soliton energy ratio obtained from measured time series, we further apply a probabilistic directional filtering method to remove the directional interference. Three wave records from the Eluanbi station are found to retain high soliton energy ratios after the directional interference has been removed, confirming that they are indeed soliton gases.

Stochastic Similarity Renormalization Group

Mon, 13 Jul 2026 00:00:00 -0400

arXiv:2607.08830v1 Announce Type: cross Abstract: By integrating the quantum Monte Carlo technique into the similarity renormalization group (SRG), we have developed a stochastic SRG framework (SRGQMC) capable of both free-space two-body and in-medium many-body evolutions. This approach circumvents the combinatorial tensor-space explosion of many-body flow equations by mapping continuous unitary transformations onto an ensemble of signed random walkers. We benchmark the SRGQMC against deterministic free-space SRG evolutions of realistic nucleon-nucleon (NN) interactions, as well as against in-medium SRG (IMSRG) many-body calculations with the Richardson pairing model at two- and three-body levels [IMSRG(2)/(3)]. While a deterministic extension to the four-body level [IMSRG(4)] remains unfeasible due to prohibitive computational costs, we have achieved the first IMSRG(4) calculation by using the stochastic technique, demonstrating a substantial improvement toward the full configuration-interaction limit. This stochastic framework provides a practical pathway to higher-order IMSRG calculations.

Energy, time, and position resolution measurements of an array of large tapered LYSO crystals

Mon, 13 Jul 2026 00:00:00 -0400

arXiv:2607.09226v1 Announce Type: cross Abstract: We report on the performance of six custom-made tapered LYSO crystals of unprecedented volume, which constitute a sector of the 19 radiation length electromagnetic calorimeter planned for the PIONEER experiment. The longitudinal response uniformity of each crystal was measured using radioactive sources before characterizing the energy and time resolution of the crystals in an array using a 20 to 80 MeV positron beam at the Paul Scherrer Institute. The array demonstrated an energy resolution better than 2 % for energies above 40 MeV and a time resolution better than 130 ps for energies above 30 MeV. The spatial resolution was measured in the central region of the array to be 4.9 mm at 70 MeV, and was extrapolated to 5.4 mm across a 30 mm radius region using Geant4 simulation. The measured properties satisfy the key design parameters of the PIONEER calorimeter for the measurement of rare pion decays.

Spin distribution of fission fragments involving bending and wriggling modes

Mon, 13 Jul 2026 00:00:00 -0400

arXiv:2412.04410v2 Announce Type: replace-cross Abstract: We present a closed analytical description of the spin distributions of the fragments produced in low-energy induced and spontaneous fission. In our model the high fragment spins and the relative orbital angular momentum arise from the zero-point transverse wriggling and bending oscillations of the two pre-fragments, under the postulate that the fissioning system remains ``cold'' up to scission -- its available energy being stored as non-equilibrium deformation rather than as heat. From the probability distributions of the two modes we derive a closed expression for the spin distribution of each fragment and for its mean value. The decisive quantities are the fragment moments of inertia, which we evaluate in the hydrodynamic model from the non-equilibrium scission deformations reconstructed from the measured prompt-neutron multiplicities. Confronted with the recent data on $\rm ^{232}Th(n, f)$, $\rm ^{238}U(n, f)$, and $\rm ^{252}Cf(sf)$, the model reproduces both the magnitude of the mean spins and their characteristic sawtooth dependence on the fragment mass. Comparison with the statistical and microscopic approaches indicates that the differences for individual fragments can be traced largely to the deformation dependence of the moments of inertia.

Imprints of octupole collectivity in uranium-238 on relativistic heavy-ion flow observables

Mon, 13 Jul 2026 00:00:00 -0400

arXiv:2504.15245v3 Announce Type: replace-cross Abstract: Some atomic nuclei exhibit enhanced octupole collectivity, reflected in finite reflection-asymmetric multipole correlations rather than necessarily in a rigid static pear-shaped ground state. Low-energy studies indicate finite octupole strength in uranium-238, commonly interpreted as soft or vibrational in nature, in addition to its large prolate quadrupole collectivity~\cite{MCGOWAN1994569,KIBEDI:2002wxc}, in addition to its large prolate quadrupole collectivity. Here we investigate how such octupole correlations can be encoded in the initial geometry of relativistic heavy-ion collisions and mapped to final-state flow observables. Using state-of-the-art hydrodynamic calculations, we demonstrate quantitative sensitivity to octupole-induced features encoded in the initial-state geometry and suggest a modest octupole collectivity in uranium-238, confirmed by the latest high-energy experimental measurements~\cite{STAR:2025elk}. These findings provide as a complementary probe of odd-order nuclear collectivity and help constrain quark-gluon plasma initial conditions.

Scaling approach to rigid and soft nuclear deformation through flow fluctuations in high-energy nuclear collisions

Mon, 13 Jul 2026 00:00:00 -0400

arXiv:2509.09376v2 Announce Type: replace-cross Abstract: The nature of octupole deformation, whether static or vibrational, remains an open question in nuclear physics. Here, we propose a scaling approach to probe this ambiguity by triangular flow fluctuations using multi-particle cumulants, $c_{3,\varepsilon}\{4\}$, in relativistic $^{238}$U+$^{238}$U collisions. We demonstrate that both $|c_{3,\varepsilon}\{4\}|$ and the ratio $|c_{3,\varepsilon}\{4\}/c^2_{3,\varepsilon}\{2\}|$ scale linearly with the fourth-order moment of octupole deformation, $\langle \beta^4_{3,\mathrm{U}} \rangle$. Combined with the known linear relation of $c_{3,\varepsilon}\{2\}$ to $\langle \beta^2_{3,\mathrm{U}} \rangle$, this new relation provides a direct extraction of both the mean and variance of the octupole deformation fluctuations, finally discriminating between static and dynamic origins. This work establishes a new tool to probe the static and dynamic collective modes in high-energy nuclear collisions, advancing a significant step toward refining the initial conditions of quark-gluon plasma.

Synchronization modes in bipartite oscillator networks

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2606.20345v3 Announce Type: replace Abstract: Collective oscillations in neuronal systems often arise from interactions between excitatory and inhibitory populations rather than from recurrent coupling within a single ensemble. Motivated by the coexistence of strongly and partially synchronized regimes in such systems, we study the Kuramoto Sakaguchi model on a bipartite network. Despite its minimal structure, the model exhibits rich collective dynamics, including both continuous and discontinuous transitions from full synchrony to partial synchrony (PS). In the PS regime, global oscillations fail to entrain one of the two populations, whose oscillators display quasiperiodic dynamics with an average frequency that can significantly deviate from that of the global field, as observed in neuronal networks. We show that this PS state constitutes an example of self-organized quasiperiodicity, arising here in the canonical Kuramoto Sakaguchi model despite its purely linear global coupling.

Manifold-adapted radial basis functions for reduced-order modelling of chaotic flows

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2607.08571v1 Announce Type: cross Abstract: Chaotic systems often evolve on a low-dimensional attractor whose geometry varies from one region to another. We propose a non-intrusive reduced-order model that reads this local geometry by clustering and uses it to shape a radial basis library whose kernels adapt to each region. Fitting the reduced velocity onto this library by one global regularised least-squares solve gives an explicit, differentiable vector field that reproduces the long-term statistics, that is, the invariant measure, without any use of the governing equations. Since a radial basis field decays away from the data and cannot by itself return an escaped state, the integration is stabilised by a kinematic corrector whose magnitude is reported as a measure of how far each result rests on the learned field rather than on the corrector. On Lorenz-63 the model recovers the attractor, its marginal densities, and the positive and neutral Lyapunov exponents, while under-recovering the strong transverse contraction. On Lorenz-96 its valid prediction time is competitive with tuned neural-network and reservoir-computing forecasters, and the invariant measure is reproduced on both the full state and a reduced observable. On the Kuramoto--Sivashinsky equation and the quasiperiodic Kolmogorov flow the model matches the energy distribution and spectrum of an intrusive quantised-local Galerkin model, and improves on a global Galerkin projection of the same dimension, without ever projecting the governing equations.

Full-Spectrum Quantum Simulation for the Nuclear Shell Model

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2607.08235v1 Announce Type: new Abstract: The nuclear shell model is a general way of expressing the many-body nuclear Hamiltonian and deciphering the underlying nuclear structure. In today's era of modern and high-power computation, the primary limitation of the nuclear shell model is the enormous dimensionality of its Hilbert space, which far exceeds available storage capacity and prevents the diagonalization of the full Hamiltonian matrix in that space. Quantum computing offers a scalable solution to bypass this curse of dimensionality. In this work, we introduce a single-run quantum simulation capable of obtaining multiple shell-model eigenstates simultaneously. The nuclear Hamiltonian is transformed from a bit to a qubit basis using the Jordan-Wigner transformation, explicitly preserving fermionic anti-commutation. We employ a Subspace Search Variational Quantum Eigensolver (SSVQE) along with an Adaptive Derivative-Assembled Pseudo-Trotter (ADAPT) ansatz to construct the quantum circuit required to solve the shell-model problem. The ADAPT-SSVQE algorithm uses a symmetry-preserving single and double-excitation operator pool and optimizes a weighted energy sum to obtain the simultaneous convergence of all eigenstates within a targeted MJ subspace, eliminating the need for post-processing efforts to extract excited spectra. We benchmark this approach by solving the problem for two and three identical nucleons in a j = 9/2 orbital, successfully extracting five and ten mutually orthogonal states, respectively, within a 10-qubit active space. The algorithm achieves spectroscopic accuracy, in simulation, relative to exact diagonalization and intrinsically restores total angular momentum (\hat{J}^2) symmetry.

Relativistic Mean Field Approach with Chiral Symmetry Breaking and Quark Confinement in the light of Astrophysical Observations

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2607.08412v1 Announce Type: new Abstract: We perform a Bayesian analysis of a relativistic mean-field approach, which is an implementation of the chiral confining model with both chiral symmetry breaking and confinement effects, and which was recently proven to reproduce well the ground state properties of finite nuclei. We additionally explore the impact of couplings between $\rho$ and $\omega$ mesons as well as a non-linear $\omega$ coupling. Our models are simultaneously constrained by nuclear matter properties near saturation density, multi-messenger neutron star astrophysical observations, and/or lattice QCD predictions of the nucleon mass. It exhibits tension in simultaneously reproducing the $\sim 2M_{\odot}$ massive NS and the tidal deformability inferred from GW170817. We show that an additional $\omega\rho$ coupling, favored by Bayes factor analysis, substantially alleviates this tension, while adding a non-linear $\omega$ self-interaction is not necessary for the RMF-CC model. Owing to the strong constraints on the scalar sector imposed by chiral dynamics and the softening of the equation of state at high densities induced by our treatment of confinement, the RMF-CC approach favors stiff equations of state. Since we do not consider phase transition in the core of neutron stars, this stiffening is obtained with large values of the incompressibility modulus of about $\sim300$ MeV. We finally compare the well-known RMF model with RMF-CC models with the same constraints, and we obtain a preference for the RMF model in the absence of a phase transition in the core of neutron stars.

Charge radii of calcium isotopes within relativistic configuration-interaction density functional theory

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2607.08478v1 Announce Type: new Abstract: The charge radii of calcium isotopes are investigated within the framework of relativistic configuration-interaction density functional (ReCD) theory. The ReCD theory microscopically incorporates beyond-mean-field correlations through rotational symmetry restoration and configuration mixing among quasiparticle excited states, and treats even-even and odd-$A$ isotopes on the same footing. It is found that beyond-mean-field correlations significantly soften the potential energy surfaces of calcium isotopes and shift the energy minima from nearly spherical mean-field solutions to deformed shapes. The quadrupole deformation parameters predicted by the ReCD theory show much better agreement with the available experimental data than the mean-field results, supporting the reliability of the calculated potential energy surfaces and highlighting the important role of beyond-mean-field correlations. Owing to the sensitive dependence of charge radii on nuclear deformation, the charge radii obtained within the ReCD framework are generally larger than the mean-field predictions. The nearly identical charge radii of $^{40}\mathrm{Ca}$ and $^{48}\mathrm{Ca}$, as well as the unexpectedly large charge radius of $^{52}\mathrm{Ca}$, are well reproduced. Compared with the mean-field calculations, the description of the odd-even staggering is improved, especially for the enhanced charge radii of $^{42}\mathrm{Ca}$ and $^{44}\mathrm{Ca}$. It is also worth noting that secondary local minima appear in the ReCD-based potential energy surfaces of the odd-$A$ calcium isotopes $^{41,43,47}\mathrm{Ca}$. The present results suggest that shape mixing between different local minima, which is not fully included in the present calculation, may further improve the description of the pronounced odd-even staggering observed in calcium isotopes.

Microscopic description of $^{12}$C+$^{12,13}$C fusion reactions at nuclear astrophysical energies

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2607.08502v1 Announce Type: new Abstract: The $^{12}$C + $^{12}$C fusion reaction plays a key role in several astrophysical phenomena. However, it is difficult to determine its cross sections in the relevant energy region because of both low cross sections and strong resonant structures. On the other hand, the $^{12}$C + $^{13}$C system shows a much smoother energy dependence of fusion cross sections. To simultaneously analyze the $^{12}$C + $^{12,13}$C systems, we here develop a reaction model that explicitly treats the entrance channel and the compound nucleus states. For this purpose, we combine the discrete basis model for the entrance channel and the shell model for the compound nuclei. The coupling strengths between the entrance channel and the compound nucleus states are determined so that the fusion cross sections for these systems match with each other at the resonance energies for the $^{12}$C + $^{12}$C system, as has been observed experimentally. The model successfully reproduces the significantly different behaviors of fusion cross sections in these systems.

Secondary Hadron--Nucleus Collisions of Short-Lived Hadrons in Ultra-Relativistic Fixed-Target Heavy-Ion Interactions

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2607.08658v1 Announce Type: new Abstract: Ultra-relativistic heavy nuclei traversing a solid target undergo successive nuclear encounters separated by atomic lattice spacings. At sufficiently high beam energies, Lorentz contraction reduces the proper time between collisions to $\mathcal{O}(10^4)$~fm$/c$ in the center-of-mass frame of the first interaction. We then consider the fragmentation region of this first collision, and show that short-lived hadrons produced in this region, with additional Lorentz boost, can reach the next nucleus before decaying. We show that this geometry enables secondary hadron--nucleus collisions involving species that cannot be realized as conventional secondary beams or in subsequent hadron--nucleus interactions in cosmic-ray cascades. For a $2.76$ TeV-per-nucleon Pb beam incident on a solid Pb lattice, we determine which forward-produced hadrons can survive to a second interaction, estimate their collision probabilities, and analyze potential observable consequences. In particular, we identify some representative hadrons whose proper lifetimes are of order $10^3$ fm/c, e.g. specific mesons ($\eta^\prime$) and heavy-flavor resonances ($J/\psi, D^*(2010)$), as projectile species that become accessible through this collision space-time geometry. At substantially higher beam energies (for example, with 10 TeV per-nucleon Pb beam), the survival probabilities are significantly enhanced. This can make even very short lived hadrons with life times of few tens fm ( $\Xi(1530)$, $\omega(782)$, $\phi(1020)$) available for this secondary hadron-nucleus collision, providing an additional motivation for future ultra-relativistic fixed-target heavy-ion experiments.

Nuclear Many-Body Systems as Benchmarks for Quantum Computing

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2607.08047v1 Announce Type: cross Abstract: We present a framework for benchmarking quantum algorithms for nuclear many-body systems based on realistic nuclear Hamiltonians such as chiral effective field theory. To this effect we introduce a workflow that maps nuclear interactions in second quantization formalism to qubit Hamiltonians. This enables the systematic construction of benchmark instances spanning no-core and valence-space formulations with two-body (NN) and selected three-body (3N) interactions. Then, we proceed to provide resource estimates for three representative eigenvalue algorithms: Quantum Phase Estimation, Quantum Krylov methods, and Observable Dynamic Mode Decomposition. We compare their resource requirements in terms of T-gate counts and system size, and examine the impact of model-space choices and many-body interactions. The primitives included in our analysis are Trotterization, Qubitization, and Quantum Singular Value Transformation. Our results quantify scaling trends across algorithms and problem classes, and provide a basis for consistent comparisons of quantum approaches to nuclear many-body problems. The implementation is provided by the NuQuLib software stack.

Collective excitations in the hot QCD medium and the propagation of Heavy Quarks

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2410.20770v2 Announce Type: replace Abstract: This review explores the current understanding of collective excitations and the dynamics of heavy quark propagation in the quark-gluon plasma (QGP) formed in relativistic heavy-ion collisions. We focus on three core aspects: the theoretical modelling of the QGP, including momentum anisotropy, medium-induced collisions, finite chemical potential, and non-ideal interactions; the collective behaviours within the plasma; and the interaction dynamics of heavy quarks as they traverse the medium. Along with the polarization energy loss mechanisms, we also review the possibility of energy gain due to thermal field fluctuations. Lastly, we discuss how these theoretical insights can be tested through experiments and outline possible directions for future research.

Maris polarization in the ($p,pd$) reaction

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2511.16899v2 Announce Type: replace Abstract: Proton-induced knockout reactions at intermediate energies provide a clean probe for nuclear clusters. The Maris polarization, which is the effective polarization of a particle inside a nucleus arising from nuclear absorption and spin-orbit coupling, has been used in proton knockout to determine the total angular momentum $j$ of the removed protons. However, its manifestation in cluster knockout remains unexplored. We theoretically demonstrated that the Maris polarization can be observed via the vector analyzing power $A_y$ of the proton-induced deuteron knockout (p,pd) reaction in imbalanced kinematics. First, we computed the spin correlation coefficient $C_{y,y}$ of p-d elastic scattering, which is an elementary process, to identify suitable kinematics for the Maris polarization. Subsequently, we calculated the $A_y$ values of the (p,pd) reaction at 250 MeV for deuteron-cluster orbits with $j=1$, $2$, and $3$. The large positive $C_{y,y}$ values at p-d scattering angles of $\sim 40^\circ$ are consistent with the experimental data. In the corresponding (p,pd) kinematics, the signs of $A_y$ for $j=3$ and $1$ orbits are positive and negative, respectively, indicating effective upward and downward polarizations of the deuterons in the nucleus. The $A_y$ value for $j=2$ orbit lies between those for the other two orbits, which can also be explained by the Maris polarization, with the deuteron being knocked out from regions near the poles of the $y$-axis. These results are nearly independent of the deuteron internal state and the nucleon-nucleon effective interactions adopted. We theoretically demonstrated that the Maris polarization occurs in the (p,pd) reaction under imbalanced kinematics. This work may lead to the establishment of the concept of deuteron-cluster orbit. Further experimental and theoretical studies are required to improve the quantitative understanding of this effect.

The Role of Ab Initio Beta-Decay Calculations in Light Nuclei for Probes of Physics Beyond the Standard Model

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2602.00341v2 Announce Type: replace Abstract: Precision beta decay experiments serve as powerful probes of physics beyond the Standard Model, enabling stringent tests of fundamental symmetries of nature. In particular, these experiments primarily focus on precise determinations of the Cabibbo-Kobayashi-Maskawa matrix element Vud and the search for exotic weak currents, both of which depend critically on theoretical calculations of radiative, recoil-order, and isospin-breaking corrections with quantified uncertainties. In recent years, ab initio nuclear many-body methods--grounded in realistic nucleon-nucleon interactions and systematically improvable approximations--have advanced considerably in their ability to compute these higher-order corrections for various nuclei. This review provides a comprehensive overview of state-of-the-art ab initio calculations of beta-decay corrections, encompassing both radiative corrections and recoil-order terms, and examines their significance for precision tests of the Standard Model. We discuss the theoretical formalisms employed, including the integration of effective field theory frameworks with many-body approaches. Particular attention is given to recent results for superallowed Fermi decays (e.g., 10C -> 10B and 14O -> 14C) and allowed Gamow-Teller transitions (e.g., 6He -> 6Li, 8Li -> 8Be, 8B -> 8Be), where ab initio calculations have achieved unprecedented precision. We also highlight emerging calculations for unique forbidden decays, which offer complementary sensitivity to BSM physics. Finally, we outline future directions aimed at extending the reach of ab initio calculations to heavier nuclei and additional decay modes, thereby strengthening the synergy between theory and experiment in the ongoing search for new physics.

High-order perturbative calculations of nuclear ground states: Automated evaluation of many-body diagrams

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2607.00119v2 Announce Type: replace Abstract: We advance the many-body perturbation theory (MBPT) calculations of the ground-state energy and radius of closed-shell nuclei beyond third order. Using automated diagram generation and evaluation up to fifth order, we present ground-state properties of selected closed-shell nuclei up to $^{78}$Ni with two- and three-nucleon interactions derived from chiral effective field theory. A clear convergence trend is observed for the ground-state energy enabling calculations at improved accuracy. We further investigate in detail the decomposition of the fourth-order contributions. For the ground-state energy, the magnitude of the fourth-order contribution is typically less than half of the third order, and a typical cancellation among different classes of diagrams is observed. Finally, we perform a comprehensive comparison between MBPT and non-perturbative in-medium similarity renormalization group (IMSRG) calculations, with the goal to provide insight into many-body uncertainties associated with the IMSRG(2) truncation.

Melting of heavy quarkonia in QGP using deep neural networks

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2509.14970v2 Announce Type: replace-cross Abstract: Machine learning techniques have emerged as powerful tools for tackling non-perturbative challenges in quantum chromodynamics. In this study, we introduce a data-driven framework employing deep neural networks to systematically predict the temperature-dependent behavior of the screening mass $m_D(T)$ and the strong coupling constant $\alpha_s(T)$ within a quark-gluon plasma medium. These medium-sensitive quantities are subsequently employed to compute the thermal widths $\Gamma_{\text{n}}(T)$ and binding energies $E_B(T)$ of heavy quarkonia states, specifically charmonia and bottomonia, by numerically solving the Schr\"odinger equation with medium-modified heavy quark potentials. To estimate the dissociation temperatures $T_d$ of various quarkonia states, we employ two complementary dissociation criteria: the conventional one, where $2E_B(T_d) = \Gamma_{\text{n}}(T_d)$, and an additional lower bound criterion defined by $E_B(T_d) = 3T_d$. This dual-criterion approach provides a more constrained and physically motivated estimate of the temperature range over which quarkonia states dissolve in the QGP environment. Our machine learning-enhanced predictions show excellent agreement with available lattice QCD results, especially for the ground states $\Upsilon(1S)$ and $J/\psi$, and offer new perspectives on the sequential suppression pattern detected in relativistic heavy-ion collision experiments. Overall, this work advances the quantitative description of quarkonium suppression and demonstrates the prospect of modern machine learning methods to bridge theoretical predictions and experimental observations, thereby contributing significantly to QGP tomography.

Non-universality of color transparency onset in pion and kaon electroproduction

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2604.05612v3 Announce Type: replace-cross Abstract: A combined analysis of the Jefferson Lab data on nuclear transparency in $A(e,e'\pi^+)$ and $A(e,e'K^+)$ shows that the onset of color transparency (CT) is not universal across the meson flavors. The pion transparency is well reproduced by the standard quantum diffusion model (QDM) with $\Delta M^2_\pi \simeq 0.7$ GeV$^2$, whereas the kaon data favor the quadratic expansion of the naive parton model (NPM) with the natural hadronic scale $R_K \sim \sqrt{\sigma_{KN}/\pi}$. This dichotomy cannot be repaired by adjusting parameters: the pion slope excludes the quadratic expansion with any physical radius, and the kaon slope excludes the diffusion picture with any physical mass gap. A microscopic interpretation, in which the diffusive evolution of the pion appears as an exceptional consequence of its Goldstone-boson nature while the kaon follows the generic ballistic expansion, is discussed.

The Generalization Gap in Machine Learning EoS Inference from Core-Collapse Supernova Gravitational Waves

Fri, 10 Jul 2026 00:00:00 -0400

arXiv:2607.06736v2 Announce Type: replace-cross Abstract: Core-collapse supernova gravitational waves may carry information about the dense matter equation of state (EoS), which describes the relation between pressure, density, temperature, and composition. This work tests a crucial question for physical inference: can a machine learning model trained on a finite simulation catalogue predict EoS parameters for an EoS family that was absent during training? Under standard random cross-validation, a LightGBM regressor appears highly successful, yielding $R^2=(0.70,0.67,0.60)$ for the nuclear incompressibility, symmetry energy, and slope parameter $(K_0,J,L)$. However, under Leave-One-EoS-Out (LOEO) validation, where all waveforms from a single EoS are withheld, the model fails, yielding mean absolute errors of $(44.57,3.19,30.54)$ MeV and negative pooled $R^2$ scores, performing worse than a baseline mean predictor. This generalisation gap persists across linear models, random forests, neural networks, and gradient-boosted trees. Restricting inputs to physical features (bounce amplitude, bounce width, peak frequency) reduces template leakage, the memorisation of related templates shared across random splits, but does not restore reliable EoS extrapolation. In contrast, a progenitor mass case study shows that classification generalises to unseen rotation speeds, while continuous mass regression compresses predictions towards the catalogue interior. These results demonstrate that while machine learning successfully interpolates within current waveform catalogues, this does not imply robust physical inference for unseen EoS models. Future pipelines should adopt leave-family-out validation, wider simulation coverage, and physics-aware inference frameworks.

Maximal mass of neutron stars constrained by neutron star observations

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2605.00437v2 Announce Type: replace-cross Abstract: We investigate constraints on the high-density equation of state (EOS) of neutron star matter by analyzing the probability distributions of the endpoints of mass-radius M(R) sequences within a Bayesian weighting framework. Starting from two representative hadronic baseline EOSs, SFHo and DD2, matched at higher densities to an extended linear sigma model description and constrained to approach perturbative QCD (pQCD) results, we construct families of causal hybrid EOSs spanning a broad range of stiffness at supranuclear densities. Observational constraints from the binary neutron-star merger GW170817, mass-radius measurements from the Neutron Star Interior Composition Explorer (NICER), and candidate low-mass and mass-gap compact objects are incorporated through Bayesian likelihood weighting. This approach allows us to determine probability distributions for the maximum neutron-star mass M$_{\rm TOV}$ and the corresponding radius R$_{\rm TOV}$, i.e., the endpoints of the M(R) sequences. We find that the maximum-mass distributions are largely determined by observational constraints and show only weak sensitivity to the choice of baseline EOS, favoring values around 2.2-2.3 M$_\odot$ when the most robust constraints are applied. In contrast, the corresponding radius distributions exhibit a stronger dependence on the underlying hadronic EOS, with typical preferred values near $12\pm 1$ km. Additional tidal-deformability constraints further restrict the allowed parameter space and disfavor very stiff EOS realizations when interpreted together with the possible mass-gap neutron-star candidate. Our results demonstrate that endpoint distributions of M(R) sequences provide a sensitive and complementary diagnostic for constraining the high-density behavior of the neutron-star EOS within a multimessenger Bayesian framework.

The diffusion equation is compatible with special relativity

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2601.19464v2 Announce Type: replace-cross Abstract: Due to its parabolic character, the diffusion equation exhibits instantaneous spatial spreading, and becomes unstable when Lorentz-boosted. According to the conventional interpretation, these features reflect a fundamental incompatibility with special relativity. In this Letter, we show that this interpretation is incorrect by demonstrating that any smooth and sufficiently localized solution of the diffusion equation is the particle density of an exact solution of the relativistic Vlasov-Fokker-Planck equation. This establishes the existence of a causal, stable, and thermodynamically consistent relativistic kinetic theory whose hydrodynamic sector is governed exactly by diffusion at all wavelengths. We further demonstrate that the standard arguments for instability arise from considering solutions that admit no counterpart in kinetic theory, and that apparent violations of causality disappear once signals are defined in terms of the underlying microscopic data.

Degenerate coupled-cluster theory

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2601.17163v5 Announce Type: replace-cross Abstract: A size-extensive, converging, black-box, ab initio coupled-cluster ($\Delta$CC) ansatz is introduced that computes the energies and wave functions of states from any degenerate or nondegenerate Slater-determinant references with any numbers of $\alpha$- and $\beta$-spin electrons, any patterns of orbital occupancy, any spin multiplicities, and any spatial symmetries. For a nondegenerate reference, it reduces to the single-reference coupled-cluster ansatz. For a degenerate multireference, it is a natural coupled-cluster extension of degenerate Moeller-Plesset perturbation ($\Delta$MP) theory. For ionized and electron-attached references, it is a coupled-cluster Green's function, although the present theory is convergent toward the full-configuration-interaction (FCI) limits, while Feynman-Dyson many-body Green's function (MBGF) theory generally is not. Its single-excitation instance is a projection Hartree-Fock theory as per the Thouless theorem, which may be useful for core ionizations, high-spin states, and possibly electron affinities. A new multireference coupled-cluster theory for a general model space is also developed. This quasidegenerate coupled-cluster (QCC) theory is exactly converging, but not black-box, and intended for strong correlation. Determinant-based, general-order algorithms of $\Delta$CC and QCC theories are implemented and compared with configuration-interaction (CI) and equation-of-motion coupled-cluster (EOM-CC) theories through octuple excitations and with $\Delta$MP and MBGF theories up to the nineteenth order. An algebraic, optimal-scaling algorithm of $\Delta$CC theory is computer-synthesized at the levels of single excitations ($\Delta$CCS) and of single and double excitations ($\Delta$CCSD). The order of performance is: QCC $\approx$ $\Delta$CC > EOM-CC > CI at the same order or QCC $\approx$ $\Delta$CC > $\Delta$MP > MBGF at the same cost scaling.

Effective field theory for dissipative photons from higher-form symmetries

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2601.00605v2 Announce Type: replace-cross Abstract: Recent developments in generalized symmetries have provided new insights into quantum field theories. Within this framework, photons can be understood as Nambu-Goldstone modes associated with a spontaneously broken higher-form symmetry. In this work, we develop an effective field theory that builds on this symmetry structure to describe the real-time dynamics of photons in insulating media at finite temperature. Combining the Schwinger-Keldysh formalism with the generalized coset construction, we formulate a symmetry-based effective action that incorporates both conservative and dissipative effects. The effective theory implements the dynamical Kubo-Martin-Schwinger symmetry, ensuring consistency with the fluctuation-dissipation relation and Onsager's reciprocal relations. Within this framework, we derive the entropy current associated with dissipative photon dynamics and demonstrate the non-negativity of its divergence, in accordance with the second law of thermodynamics. We also clarify the symmetry origin of the gauge redundancy in the unbroken phase within the Schwinger-Keldysh framework, relating it to strong and weak realizations of higher-form symmetries. Our results provide a model-independent effective description of photon dynamics in insulating media at finite temperature.

Uncertainty quantified three-body model applied to the two-neutron halo $^{22}$C

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2604.06139v2 Announce Type: replace Abstract: Two-neutron halo nuclei offer a fascinating probe into the behaviour of quantum few-body systems at the limits of binding. Although few nuclei have already been clearly identified, many of their properties remain poorly constrained. $^{22}$C, one of the heaviest, still lacks a precise identification of its static and dynamic properties, such as its mass and dipole strength in the continuum. One main difficulty is that properties of two-neutron halo nuclei are inferred from experimental data using a theoretical model. Therefore, accurately determining the characteristics of two-neutron halo nuclei requires an accurate theoretical model and careful quantification of the uncertainties. In this work, we examine $^{22}$C with a three-body model, seeing $^{22}$C as a $^{20}$C core and two halo neutrons, and quantify for the first time the uncertainties associated with the $^{20}$C-$n$ interaction using a Bayesian approach. We propagate these uncertainties to properties of bound and scattering states of $^{22}$C, as well as its dipole strength. The comparison of our prediction for the matter radius to experimentally-derived values suggests that $^{22}$C is bound by less than 0.35~MeV and is dominated by a $(s_{1/2})^2$ configuration. Our analysis of the dipole strength shows that final-state interaction needs to be included for an accurate description, the uncertainties on the strength function are about 50\% and are mostly influenced by uncertainties on the ground-state properties, and partial-wave occupation of $^{22}$C depends on the scattering length and the $d_{3/2}$ resonance energy of the $^{20}$C-$n$ unbound system. Such sensitivity of the dipole strength to the properties of both $^{21}$C and $^{22}$C properties motivates a precise measurement of the $^{22}$C dipole strength function, that will allow to precisely and accurately resolve the spectroscopy of these nuclei.

Microscopic quasifission dynamics of the ${}^{54}\text{Cr}+{}^{243}\text{Am}$ reaction

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2603.08479v2 Announce Type: replace Abstract: Synthesizing superheavy elements (SHEs) like $Z=119$ is severely hindered by the dominant quasifission (QF) channel, which prevents compound nucleus formation. Understanding QF dynamics is thus essential for future experiments. We investigate the QF mechanisms in the $^{54}\text{Cr}+^{243}\text{Am}$ reaction, a key candidate system for SHE 119, emphasizing the roles of projectile orientation and incident energy. Calculations are performed using the fully microscopic time-dependent Hartree-Fock theory based on the Skyrme energy density functional. We conduct systematic simulations covering a broad set of initial orientations of the deformed $^{54}\text{Cr}$ and $^{243}\text{Am}$ nuclei, alongside a finely spaced range of incident energies extending from below to well above the Coulomb barrier. Our fixed-energy results show that projectile side collisions are governed by shell effects driving heavy and light fragments toward spherical $Z=82$ and deformed $N=52\text{--}56$ closures, respectively, whereas tip collisions exhibit weaker shell influence. These shell-dominated reactions are characterized by shorter interaction times, attributed to the enhanced rigidity of shell-stabilized fragments accelerating neck rupture. The energy dependence reveals a complex evolution where the system transitions from an octupole-stabilized regime ($Z \approx 88$) to a spherical shell-driven regime, with specific energy windows exhibiting suppressed shell influence. Our study demonstrates that the manifestation of shell effects in QF is a dynamical outcome sensitively dependent on both collision geometry and incident energy. Systematically probing this energy sensitivity is crucial for identifying optimal incident energies where the QF process exhibits suppressed shell influence, thereby potentially enhancing the fusion probability and improving the prospects for synthesizing new SHEs.

The quasi-normal modes of relativistic Fokker-Planck kinetic theory

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2601.19474v2 Announce Type: replace Abstract: Employing the well-known unitary equivalence between Fokker-Planck operators and Schr\"odinger Hamiltonians, we compute the quasi-normal-mode spectrum of ultrarelativistic kinetic theories with momentum-space diffusion. We show that the collision operator reduces to a Dirac-delta Schr\"odinger problem in one spatial dimension, and to a Coulomb Schr\"odinger operator with hydrogenic spectrum in three dimensions. Finite spatial wavenumber appears as a perturbation of the associated quantum potential. The hydrodynamic mode is found to obey exact Fick-type diffusion at all real wavenumbers, whereas relativistic kinematics generically produces a continuous ballistic band in the non-hydrodynamic sector, a feature absent in the Newtonian regime.

Halo structure of $^6$He from $\textit{ab initio}$ two-nucleon spatial correlations

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2512.24123v2 Announce Type: replace Abstract: We evaluate pairwise correlations using ground state wave functions for $^4$He and $^6$He obtained by $\textit{ab initio}$ no-core shell model calculations with the Daejeon16 nucleon-nucleon interaction plus Coulomb interaction, to characterize the structures of these two systems. We demonstrate that two-nucleon spatial correlations, specifically the pair-number operator $r^0$ and the square-separation operator $r^2$ projected on two-body spin $S$ and isospin $z$ components encode important details of the halo structure of $^6$He. We also analyze the single-particle state occupancies and the two-body state occupancies for the ground state of $^4$He and $^6$He. Our results indicate that the two valence neutrons in the ground state of $^6$He dominantly form a spin-singlet configuration. The rms pair separations between core nucleons and halo neutrons of $^6$He are, on average, about 80% larger than pair separations within the swollen and off-centered "$\alpha$ core". We show that this off-centering effect is primarily responsible for the observed increase in point-proton radius $r_p$ in $^6$He relative to $^4$He.

Hadronic vacuum polarization in hydrogen-like atoms and ions amid the interplay of recoil and finite-size effects

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.07658v1 Announce Type: cross Abstract: Hadronic vacuum polarization (hVP) enters simple atomic systems at a level that is small yet decisive for the precision spectroscopy now underway. We evaluate the hVP contributions to the Lamb shift and the hyperfine splitting (HFS) in ordinary and muonic hydrogen (H and $\mu$H) and hydrogen-like helium-3 ions ($^3$He$^+$ and $\mu^3$He$^+$), using the dispersive data-driven approach and state-of-the-art empirical parametrizations of the $R$ ratio. At the centre of the analysis is the interplay of recoil and finite-size effects: the recoil corrections that dominate the HFS in muonium (Mu), where both constituents are pointlike, are shown to be suppressed by the nuclear elastic form factors (FFs). Our results for the leading hVP contribution to the Lamb shift agree with the literature within uncertainties. Furthermore, we present a first evaluation of the subleading $O(Z^5\alpha^6)$ hVP-finite-size correction, which is by no means negligible in $\mu^3$He$^+$. Our results for the hVP contribution to the HFS deviate significantly from all previous evaluations. For the ground-state HFS, we obtain $2.153(11)~\mu$eV in $\mu$H and $-15.19(57)~\mu$eV in $\mu^3$He$^+$, as well as $0.0860(4)~$kHz and $-0.476(17)~$kHz in ordinary H and $^3$He$^+$, respectively. Notably, our result for $\mu$H differs from previous evaluations by roughly ten times the experimental precision anticipated by the upcoming CREMA and FAMU measurements.

Double quarkonium production in hadronic collisions at fixed-target experiments

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.07312v1 Announce Type: cross Abstract: We present new results for double quarkonium production in (un)polarized hadronic collisions at fixed-target experiments. Our approach incorporates the transverse momentum dependent factorization in combination with the Color-Singlet Model. We present new analytical expressions for the angular structure of the cross section for the $q\bar q$-induced channel, and provide predictions for the unpolarized cross section and transverse single-spin asymmetries for present and future fixed-target experiments at CERN and the LHC.

Collins effect in pion-in-jet production in polarized $pp$ and $ep$ collisions

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.06821v1 Announce Type: cross Abstract: We study Collins azimuthal asymmetries for pion-in-jet production in polarized proton-proton and lepton-proton collisions. We adopt a hybrid transverse momentum dependent approach, with a collinear configuration for the initial state, and employ the transversity and Collins fragmentation functions extracted from semi-inclusive deep inelastic scattering and $e^+e^-$ annihilation data. After recalling the good description of the STAR data in $pp$ collisions, which supports the universality of the Collins function, we present predictions for Electron-Ion Collider kinematics, both at leading order and by including the quasireal photon exchange in the Weizs\"acker-Williams approximation. This contribution is sizable but does not spoil the dominance of quark-initiated channels. This implies that $\ell p$ processes allow for a clearer access to the transversity distribution, including its sea-quark component.

Anomaly Realization in Charge-Flux Detector Correlators

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.06667v1 Announce Type: cross Abstract: Quantum anomalies provide a bridge between ultraviolet properties of a theory and its infrared sector. We study how this connection appears in axial-charge-flow observables. In the simplest example, an axial-charge detector probes the fermionic cut of the anomalous triangle and resolves its infrared content as an angular distribution. The massless limit does not commute with the angular integration: a contribution suppressed at fixed angle collapses onto the two beam-collinear directions while retaining the finite integrated sum rule fixed by the axial anomaly. We then replace the axial-charge detector by higher-spin helicity (zilch) detectors and study a family of axial-anomaly-controlled energy-weighted sum rules for the corresponding fluxes. We further show that the same singular localization mechanism and finite zilch-flux sum rules persist in the mixed axial-gravitational channel. We briefly comment on extensions to more general states and multipoint correlators.

Three-flavor supernova neutrino simulation using a hybrid quantum-classical algorithm with qutrits

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2605.01099v1 Announce Type: cross Abstract: We simulate a self-interacting three-flavor neutrino system within a core-collapse supernova using a hybrid classical-quantum algorithm on a qutrit computer. Based on the Dirac-Frenkel evolution equations, we employ a variation of the quantum-assisted simulator (QAS) to calculate the system's time evolution operator by performing qutrit Hadamard tests to find expectation values of unitary operators in the Hamiltonian. The time evolution simulation is then done classically. We find that the hybrid algorithm produces results comparable to an exact numerical integration out to times of $t \approx 30 \,\omega_0^{-1}$ with time step $\delta t = 0.005 \,\omega_0^{-1}$, where $\omega_0$ is the energy scale of the single neutrino vacuum oscillations. We discuss the lessons learned in simulating neutrino systems using this hybrid quantum-classical algorithm, along with the advantages it offers over quantum Trotterization.

Extracting Barrier Distributions from Fusion Cross Sections

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.07551v1 Announce Type: new Abstract: Studying fusion cross sections provides insight into the fusion process, details about the internal structure of heavier nuclear systems, and a window into astrophysical processes. Barrier distributions, extracted from fusion excitation functions, are immensely useful for comparing theoretical model predictions and experimental results. Extracting this barrier distribution from the measured cross-section data amounts to taking the second derivative of the energy-weighted cross section. In practice, barrier distributions are highly sensitive to the quality of collected experimental data and the choice of step size when using standard point difference schemes. In this work, we explore Bayesian methods for extracting a posterior distribution over barrier distributions that could reasonably describe experimental data. We benchmark Gaussian processes and recently developed Bayesian machine learning inference algorithms against realistic simulated data generated from a simple model of fusion excitation functions. We find that Gaussian processes often exhibit aliasing at higher energies of the barrier distribution. We demonstrate that the BNN architectures can more faithfully recover the barrier distribution with quantified uncertainties at all energies, while also identifying key regions of high uncertainty and model discrepancy to determine precisely where additional experiments would be maximally impactful. We use our conclusions to calibrate models to measured experimental data. All methods are comparatively robust to data sparsity and irregularity, but we find that the single most important factor dictating the fidelity of all models is the relative size of experimental uncertainties. We release an open-source version of our analysis and a user-friendly implementation of our method to encourage its future usage for experimental analysis.

Hadronic and partonic composition of QCD matter across the crossover

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.07140v1 Announce Type: new Abstract: We construct a simple equation of state of strongly interacting matter at zero chemical potentials that provides a unified description of lattice QCD thermodynamics in terms of hadronic and partonic degrees of freedom. The hadronic phase is described by the quantum van der Waals hadron resonance gas, extended by excluded-volume repulsion between mesons, while the quark-gluon plasma is modeled as an ideal gas of quarks and gluons supplemented with a phenomenological interaction term proportional to $T^3$. The two regimes are connected by a smooth crossover switching function. The three model parameters - the meson hard-core radius, the strength of the partonic interaction term, and the switching temperature - are determined from a fit to lattice QCD results for the trace anomaly. The resulting equation of state reproduces the lattice data on the pressure, entropy density, energy density, and speed of sound in the temperature range $T=100$-$500$ MeV. The fit yields a meson hard-core radius $r_M \simeq 0.2$ fm, a partonic interaction scale $A \simeq 600$ MeV, and a switching temperature $T_0 \simeq 216$ MeV, substantially exceeding both the pseudocritical temperature of the QCD chiral crossover and the chemical freeze-out temperature. This finding suggests that the transition from hadronic to partonic degrees of freedom is considerably more gradual than indicated by the chiral pseudocritical temperature alone, with hadronic states remaining an important component of strongly interacting matter up to temperatures of about 250 MeV, well above the QCD chiral crossover.

Machine learning the impact parameter in heavy-ion collisions at $\sqrt{s_{\rm NN}}$ = 4 and 11 GeV: a cross-check study with UrQMD, AMPT, and JAM

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.06897v1 Announce Type: new Abstract: By generating heavy-ion collision data with the ultrarelativistic quantum molecular dynamics (UrQMD) model, a multiphase transport (AMPT) model, and the JAM model, the impact parameter ($b$) in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 4 and 11 GeV is reconstructed using supervised learning and unsupervised learning in machine learning (ML). In supervised learning, the performance of ML algorithm is cross-checked by using data obtained from these three transport models. It is found that the typical mean absolute error (MAE) which measures the average magnitude of the absolute difference between the true and predicted $b$ is between 0.2-0.4 fm, even when training ML algorithm with data generated from one model but testing with data from others. While the conventional method (i.e., a polynomial fit to multiplicity as a function of $b$) only works for data generated from the same model. In the classification task, the present ML-based method also shows significantly superior results compared to the traditional approach. In unsupervised learning, the K-means clustering algorithm is used to partition collision events directly from experimental-style observables, showing that the algorithm autonomously identifies six clusters corresponding to different centrality classes without relying on predefined model-based binning. Our study demonstrates the strong robustness of using an ML algorithm trained on transport-model data for impact-parameter determination, and indicates that this method has the potential to be generalized to handle real experimental data.

Differential cross sections for ${{^{12}\mathrm{C}(n,\alpha_{0})}}$, ${{^{16}\mathrm{O}(n,\alpha_{0})}}$ and ${{^{16}\mathrm{O}(n,\alpha_{1,2,3})}}$ between ${{E_n}}$ = 7.2 and 10 MeV with an active-target Time Projection Chamber

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2601.02841v2 Announce Type: replace Abstract: Data for the ${{^{12}\mathrm{C}(n,\alpha_{0})}}$, ${{^{16}\mathrm{O}(n,\alpha_{0})}}$ and ${{^{16}\mathrm{O}(n,\alpha_{1,2,3})}}$ differential cross sections are important for several different areas of nuclear physics such as understanding neutron transmutation in nuclear reactors. The TexAT Time Projection Chamber was used to measure the differential and angle-integrated cross sections in active-target mode. The chamber was filled with CO$_2$ gas and used a quasi-monoenergetic neutron beam from the $d(d,n)$ reaction at Edwards Accelerator Lab at Ohio University. A comparison between our current and previous results at overlapping energies and angles which showed good agreement in angular dependence and absolute cross section. A broader angular coverage than previous results demonstrated that the integrated cross section for the \po16 reaction deviates from ENDFVIII.0 evaluations. This first instance of neutron-induced measurements with an active-target Time Projection Chamber demonstrates the use of this method for high-quality differential cross section data across a broad angular range, generating good statistics with a relatively low-intensity beam.

Single inclusive hadron and jet production in lepton-hadron scattering

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.07664v1 Announce Type: cross Abstract: We present the first calculation of single inclusive hadron and jet production at large transverse momentum in lepton-hadron scattering in a joint QCD+QED factorization approach. The scattering cross section is factorized into a convolution of infrared-safe hard coefficient functions with universal lepton distribution functions (LDFs) and parton distribution functions (PDFs) of the colliding lepton and hadron, respectively, together with fragmentation functions (FFs) of the observed hadron (or jet). With joint QCD+QED factorization, the DGLAP-type evolution equations for LDFs, PDFs, and FFs necessarily have evolution kernels calculated in both QCD and QED. We derive a default set of LDFs for our calculations and discuss a strategy to extract universal, non-perturbative LDFs from future data. We present our calculations for single inclusive hadron and/or jet production at the energies of Jefferson Lab and the future Electron-Ion Collider.

Fierz-complete four-quark interactions and the QCD phase diagram

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.07354v1 Announce Type: cross Abstract: The dynamics of Fierz-complete four-quark interactions and its influence on the QCD phase diagram have been investigated within the functional renormalization group approach to QCD at finite temperature and densities. It is found that in the vacuum the pion and sigma channels play the overwhelmingly dominant role, and all the other channels are negligible. However, when it is near the critical end point (CEP), the magnitude of four-quark couplings in other channels increases sizably and they become more and more important. In comparison to the single scalar-pseudoscalar channel of four-quark interactions, the dynamics of Fierz-complete four-quark interactions increases a bit the curvature of the phase boundary, and moves the CEP to location of larger baryon chemical potential and smaller temperature.

Recent highlights from the STAR Experiment

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.07254v1 Announce Type: new Abstract: Understanding the QCD phase structure and the possible existence of a critical point remains one of the central goals of the heavy-ion program at RHIC. In this proceeding, we present recent STAR results across multiple observables that probe different aspects of the hot and dense matter created in Au+Au collisions. These include two-particle transverse momentum correlations of mean transverse momentum, net-proton cumulants up to fourth order, identical-pion femtoscopy, and baryon-strangeness correlations. We also discuss femtoscopic measurements of baryon-baryon pairs, which provide insight into hyperon-nucleon and hyperon-hyperon interactions and the possible formation of strange dibaryon states. Together, these results provide complementary probes of the system's evolution across a wide collision-energy range (sqrt(sNN) = 3-200 GeV), offering new constraints on the QCD equation of state and the location of the QCD critical point.

Unified Framework for Binary-Choice Dynamics: Analysis and Applications

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.06803v1 Announce Type: cross Abstract: We demonstrate how the unified framework for binary-choice dynamics can be used to study the role of annealed and quenched disorders in homogeneous and heterogeneous systems. The framework defines the structure of interactions between agents without imposing their functional forms. Such a high level of generality allows us to connect many different models across disciplines and find universal rules that apply to all of them. Within this framework, agents update their states under the influence of two competing mechanisms chosen according to individual preferences. We review the literature to classify existing models as homogeneous or heterogeneous based on their preference distribution, and we discuss the role of annealed (changing) and quenched (fixed) disorders in modeling these preferences. Using the framework, we derive a constraint on the transition rates. When a model meets this condition, three major things happen: annealed and quenched dynamics become equivalent, any heterogeneous system can be mapped into a homogeneous one, and oscillations cannot emerge. We illustrate these consequences using models from statistical physics, opinion dynamics, and disease spreading. Finally, we discuss the framework limitations and its potential further developments.

Impact of Channel Dynamics on Higher-order Interactions of Oscillators

Thu, 09 Jul 2026 00:00:00 -0400

arXiv:2607.07662v1 Announce Type: new Abstract: Modeling higher-order interactions (HOIs) in nonlinear networks with static topologies is often physically restrictive. We demonstrate that standard 3-body Kuramoto couplings are mathematically equivalent to pairwise connections modulated by latent variables of transmission channels. While standard HOI topologies emerge in the adiabatic limit of these variables, relaxing this constraint reveals that latent channel timescales dictate collective macroscopic states. Specifically, transmission inertia drives bistability for symmetric interaction tensors and anti-phase cluster synchronization for antisymmetric ones. Furthermore, dynamically induced clustering in global topologies emerges as a finite-size effect of the dynamics of the local channels. Ultimately, we show that relying exclusively on static topologies restricts interaction modeling. Integrating latent variables captures the transient inertia and fundamental asymmetry of physical networks, bridging the analytical utility of higher-order functions with the reality of the underlying transmission medium.

Analytical foundation for adversarial synchronization control in oscillator networks

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2605.14492v3 Announce Type: replace Abstract: This study provides an analytical foundation for adversarial synchronization control in Kuramoto oscillator networks, where small gradient-based perturbations applied repeatedly to oscillator phases can dramatically enhance or suppress collective synchronization. Using the Ott--Antonsen reduction, we derive an exact closed-form expression for the effect of a single adversarial perturbation (kick) on the order parameter. A key finding is that each kick produces a finite, coupling-independent increment in the order parameter even when synchronization is arbitrarily weak, which combined with slow relaxation near the critical coupling and mean-field feedback explains the disproportionate amplification previously observed in numerical simulations. Fixed-point analysis further reveals a fundamental asymmetry between enhancement and suppression, with the latter governed by noise-induced escape in finite systems. Extending the framework to networks via the annealed network approximation, we show that the theory captures the synchronization behavior of representative model networks and identify a decoupling between kick sensitivity and mean-field dominance in scale-free networks. These results offer a tractable theoretical basis for understanding and designing kick-based synchronization control in oscillator networks.

Wave Kinetics and Thermalization in Kadomtsev-Petviashvili-I System

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.06119v1 Announce Type: new Abstract: We study properties of solutions, both evolving and equilibrium of the wave-kinetic equation describing ensembles of weak random waves governed by the Kadomstev-Petviashivli-I equations. The latter equation is integrable by the inverse scattering method, and yet it allows resonant wave interactions leading to redistribution of energy in the Fourier space. Such resonant interactions preserve an infinite number of invariants and we find that they preserve compactness of Fourier space supports. Numerically, we observe that the system can thermalize to one of the equilibrium states of Rayleigh-Jeans type, despite the common empirical belief that thermalization is impossible for integrable systems. The thermalized states are formed via non-local spectral transfers leading to creation of strong low-wavenumber peaks of the wave spectrum -- a process akin to Bose-Einstein condensation.

When a common price signal is present, network topology leaves no fingerprint on a storage fleet's collective dynamics

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.06381v1 Announce Type: new Abstract: Price-based mean-field models of battery storage coordination usually assume that each agent responds to the true population-average charging power. Under that assumption, communication topology is irrelevant because the broadcast price already carries the coupling that matters. We study a nearby regime in which agents respond to a shared noisy forecast of the average, with correlation rho between agents' forecast errors. Analytically and in simulation, we find that topology remains undetectable in the effective-dimensional response of the fleet, even when neighbour observation is the only explicit communication signal. The mechanism is structural: the correlated forecast error projects onto the graph-invariant consensus mode, while topology acts through transverse modes. As rho N grows, the consensus-mode variance dominates and the spectral participation ratio approaches one independently of graph topology. Simulations on linear, star, and small-world graphs confirm that topology-induced variation is below the variation caused by redrawing the forecast noise. The result is not a claim that topology has no dynamical effect, but that shared stochastic forcing can mask topology-dependent modes in decentralized storage fleets.

Full configuration interaction quantum Monte Carlo for accurate $\textit{ab initio}$ nuclear structure calculations: algorithms and calculation details

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.05525v1 Announce Type: new Abstract: Full configuration interaction quantum Monte Carlo (FCIQMC) is a stochastic many-body solver that has been widely applied to electronic, molecular, and condensed-matter systems. In this work we apply FCIQMC to $\textit{ab initio}$ nuclear structure calculations using interactions derived from chiral effective field theory. We describe the algorithm in detail, including imaginary-time propagation, excitation generation, estimator choices, the initiator approximation with adaptive shift correction, and reduced-density-matrix (RDM) sampling. Benchmark calculations in small model spaces, where deterministic full configuration interaction (FCI) results are available, validate the stochastic calculation of energies, radii, and RDM-based pure estimators. For large model spaces, we analyze the residual finite-walker bias through systematic walker-number convergence and infinite-walker extrapolations. We also demonstrate that FCIQMC can be extended beyond ground-state calculations by computing the low-lying spectrum of $^6$Li.

Can average speed of sound and thermodynamic response functions signal the exotic phases in neutron star cores?

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.05555v1 Announce Type: new Abstract: The speed of sound in dense nuclear matter is crucial for understanding neutron star structure and constraining the EOS. We have discussed in details the decomposition of speed of sound via the average speed of sound and its logarithmic derivative and have connected it to the other two decomposition schemes via slope and curvature of the energy per particle or through the normalized trace anomaly and its derivative. These thermodynamic variables provide important diagnostic tools for the composition of the inner core of the compact stars. We discuss a new method of understanding phase transition and the microphysics of dense matter through the thermodynamic response functions like isothermal compressibility, baryon number susceptibility and bulk modulus in order to distinguish between local (sharp interface) and global charge (mixed phase) neutrality conditions, thereby revealing the signatures of the phase transition. The corresponding neutron-star mass--radius relations demonstrate that all considered equations of state satisfy current astrophysical constraints, while the most massive stable configurations contain either an extended mixed phase or a quark core depending on the phase-transition construction.

Self-consistent description of emission processes in axially-symmetric nuclei

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.05886v1 Announce Type: new Abstract: We present a theory of cluster emission processes in terms of proton ($\pi$) and neutron ($\nu$) single--particle (sp) degrees of freedom within a self--consistent mean--field (SCMF) constructed from a two--particle interaction having relative (rel) and center of mass (com) terms centered on the nucler surface, the latter describing the interaction between the com of a pair of particles and the surface of an axially--symmetric nucleus. In this way the $\alpha$-clustering phenomenon becomes enhanced on the nuclear surface. We present applications for unstable nuclei that decay through the emission of $\alpha$--particles above $^{100}\textrm{Sn}$, $^{208}\textrm{Pb}$ and within the actinidies series.

Full Uncertainty Quantification of Sign-Problem-Free Quantum Monte Carlo Methods and Nuclear Lattice Effective Field Theory Benchmarks

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.06044v1 Announce Type: new Abstract: Sign-problem-free quantum Monte Carlo (QMC) methods provide one of the few polynomial-scaling routes to controlled, nonperturbative benchmarks of medium-mass and heavy nuclei. We present a detailed uncertainty analysis of the recently developed sign-problem-free spin-orbit lattice action LAT-OPT1 and use it to benchmark nuclear lattice effective field theory (NLEFT). We quantify various systematic uncertainties, finding that the cumulative many-body computational uncertainty in ground-state energies of doubly magic nuclei up to $^{100}$Sn is well below the percent level. In response to recent criticism of NLEFT benchmarks, we also revisit the relation between lattice transfer matrices, lattice Hamiltonians, Hartree--Fock variational bounds, finite-box and thermodynamic-limit calculations, and the continuum-limit behavior of regulated lattice interactions. We identify several conceptual and technical errors in the analysis of Ref.~\cite{Rothman2026_NuLattice}. These include (i) the comparison of inequivalent lattice transfer-matrix and lattice-Hamiltonian calculations, (ii) an inconsistent determination of correlation energies from comparisons of Hartree--Fock and full ground-state calculations with different boundary conditions, (iii) the attribution of nuclear saturation to lattice artifacts rather than to nonlocal smearing of interactions, a mechanism that can be demonstrated in continuous space, and (iv) an incorrect renormalization of short-range two-body interactions in the continuum limit. When the same regulated lattice theory, renormalization prescription, and finite-volume boundary conditions are used consistently and analyzed properly, the reported discrepancies and concerns about the corresponding published NLEFT results are resolved.

Bottomonium production in an open quantum system approach with interactions from lattice quantum chromodynamic

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.06191v1 Announce Type: new Abstract: Bottomonium production in Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV is studied using a Lindblad master equation derived from potential non-relativistic quantum chromodynamics (QCD), where quantum regeneration of color-singlet states is matched to the lattice QCD imaginary potential via collapse operators. Two parametrizations of the in-medium heavy-quark potential, both constrained by lattice QCD data, are employed to compute the nuclear modification factors of $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$. The results show sensitivities to both the quantum regeneration effect and the initial condition of the density matrix. The dipole transitions in the collapse operators are found to significantly redistribute populations among different orbital angular momentum channels. It is shown that regeneration is more important when a potential with a larger imaginary part, i.e., stronger transitions between singlet and octet states, is used.

Interplay between Nuclear Shell Structure and Pairing around Doubly Magic $^{132}$Sn

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.05647v1 Announce Type: cross Abstract: Shell structure in finite quantum systems gives rise to sudden changes in observable properties, while pairing correlations often compete against such discontinuities. The region near the doubly magic nucleus $^{132}$Sn provides a fertile ground for testing the combined effect of shell structure and pairing. Here, we provide a novel phenomenological interpretation of existing mass data in the vicinity of the $Z=50$ and $N=82$ shell closures, which we further investigate by performing original Hartree-Fock-Bogolyubov (HFB) mean-field calculations for even-$Z$ nuclei: we find that the proton shell structure enhances an asymmetry of the neutron odd-even staggering in binding energies. We also report mass measurements of $^{137,138}$Sb, including the first experimental mass determination of $^{138}$Sb, performed using TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN). Together with existing experimental data, our results reveal an interplay between shell structure and pairing in odd-$Z$ nuclei which is more challenging to interpret phenomenologically or using HFB, thereby motivating future experimental and theoretical pairing studies in heavy neutron-rich nuclides.

Quantum decoherence: a study applied to quarkonium-like bound states in strongly interacting matter

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.06137v1 Announce Type: cross Abstract: We study the quantum decoherence of a bound state interacting with a reservoir of strongly interacting matter within the framework of open quantum systems. The bound state is modeled as a quantum harmonic oscillator whose parameters are tuned to reproduce the root-mean-square radius of $J/\Psi$ particle. The surrounding medium, representing the many degrees of freedom of strongly interacting matter, acts as an environment that induces dissipation and decoherence through system-reservoir coupling. By analyzing the time evolution of the reduced density matrix, we quantify the loss of quantum coherence and its dependence on medium properties. Subsequently, we extend the model by introducing a time dependence in the system-thermal bath coupling, thereby simulating a temperature evolution similar to that occurring during the expansion of a fireball in the central region of heavy-ion collisions. We find that a temperature evolution has a relevant impact on the way the system loses coherence through the coupling with the expanding medium. Finally, we estimate the impact of the time-dependent temperature on the decoherence process, also analyzing a scenario that includes viscous effects without finding a significant change with respect to ideal hydrodynamical evolution.

Pair Transfer and Reaction Dynamics in $^{40,48}$Ca + $^{96}$Zr Collisions Below the Coulomb Barrier

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2512.01808v2 Announce Type: replace Abstract: Sub-barrier fusion reactions are ideal for probing the effects of pairing correlations on simultaneous neutron transfer. Previous calculations using the BCS approximation showed an enhancement of pair transfer, relative to treatments with no pairing, but failed to reproduce the observed enhancement factor between one- and two-neutron transfer probabilities. This work aims to microscopically investigate the dynamics of $^{40,48}$Ca + $^{96}$Zr head-on collisions below the Coulomb barrier, focusing on the role of pairing correlations in neutron transfer. We employ time-dependent energy density functional theory extended to superfluid systems, TDSLDA. Transfer probabilities, including contributions to specific $K$-angular momentum projections, are extracted using projection operators and compared to results from calculations without pairing. Our calculations show that pairing is correlated to the dynamic deformability of the nucleus, which influences mean neutron transfer in sub-barrier reactions. We also show that TDSLDA reproduces the experimentally observed enhancement factor by significantly increasing the probability of transferring a neutron pair in the $K = 0$ spin channel. These results confirm the strong influence of pairing and structure on sub-barrier multi-nucleon transfer, and demonstrate that TDSLDA provides a reliable microscopic framework for describing the interplay between nuclear superfluidity and reaction dynamics.

A Hierarchical Bayesian Analysis of Neutron-Skin Thicknesses and Implications for the Symmetry-Energy Slope

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2602.04794v2 Announce Type: replace Abstract: Neutron-skin thicknesses provide a sensitive probe of the isovector sector of the nuclear equation of state and its density dependence, commonly characterized by the symmetry-energy slope parameter L. A wide variety of experimental and observational methods have been used to extract neutron skins, ranging from hadronic and electromagnetic probes of finite nuclei to inferences from neutron-star observations. Each approach carries distinct theoretical and systematic uncertainties, complicating global interpretations and obscuring genuine physical trends. In this work we present a hierarchical Bayesian framework for the statistically consistent synthesis of heterogeneous neutron-skin constraints. The neutron-skin thickness is modeled as a smooth latent function of isospin asymmetry and nuclear size, while method-dependent bias parameters and intrinsic nuisance widths are introduced to account for unmodeled experimental and theoretical systematics. Focusing on the tin isotopes, we infer probabilistic neutron-skin trends from 100Sn to 140Sn, finding minimal uncertainties near stability and increasing uncertainties toward the proton-rich and neutron-rich extremes. We assess the consistency of nuclear energy-density functionals and obtain conditional constraints on the symmetry-energy parameters. The resulting posterior exhibits a pronounced compression of the symmetry-energy slope parameter L, reflecting the dominant sensitivity of neutron skins to sub-saturation symmetry pressure. We demonstrate that our hierarchical Bayesian framework provides robust and transparent constraints on the sub-saturation isovector sector of the nuclear equation of state.

Bayesian Learning of (n,p) Reaction Cross Sections with Quantified Uncertainties

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2603.04789v2 Announce Type: replace Abstract: Accurate neutron-induced $(n,p)$ reaction cross sections are essential for applications in nuclear energy, radionuclide production, materials studies, and nuclear astrophysics. However, experimental data remain sparse for many isotopes, and evaluated nuclear data libraries can show systematic deviations from available measurements. We develop a Bayesian neural network (BNN) residual learning model, denoted \texttt{BNN-R5}, to improve $(n,p)$ reaction cross-section predictions. The model uses five physically motivated nuclear descriptors and does not employ experimental or evaluated cross-section values as input features. Rather than predicting the cross sections directly, \texttt{BNN-R5} learns the log-space residual between the evaluated TENDL-2023 data and experimental measurements, thereby providing a data-driven correction to the evaluated library. The model is trained using stochastic variational inference, which provides predictive mean values together with Bayesian uncertainty estimates. Across a broad range of target nuclei, the corrected cross sections generally show improved agreement with experimental data and outperform the original TENDL-2023 evaluations. Feature-importance analysis using SHapley Additive exPlanations (SHAP) identifies the pairing term $\delta$ as the most influential descriptor, followed by the excitation-energy variable $\ln(\Delta E)$ and the neutron number $N$, while the proton number $Z$ has the smallest overall influence. These results demonstrate that Bayesian residual learning provides a robust and interpretable framework for improving evaluated nuclear data and predicting reaction cross sections in data-sparse regions of the nuclear chart.

Probing the density dependence of nuclear symmetry energy through isospin transport in heavy-ion reactions

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2605.06138v3 Announce Type: replace Abstract: The density dependence of the nuclear symmetry energy remains one of the key uncertainties in contemporary nuclear physics, with significant implications for the structure of exotic nuclei, the dynamics of heavy-ion collisions, and the properties of astrophysical objects such as neutron stars and core-collapse supernovae. However, extracting robust constraints requires observables that are minimally affected by final-state interactions and are reliably predicted by transport models. This review synthesizes recent theoretical and experimental advancements in constraining the symmetry energy by leveraging isospin diffusion in heavy-ion reactions within the Fermi energy domain. Recent results from the INDRA-FAZIA collaboration, including isospin transport ratio data, and Boltzmann-Uehling-Uhlenbeck (BUU) transport model calculations are highlighted. Confidence regions for the symmetry energy are extracted from isospin transport ratios and isospin diffusion currents by utilizing state-of-the-art nuclear functionals, including both ab initio and phenomenological approaches, with a particular focus on the density regions probed by these experiments. The resulting constraints will aid future Bayesian studies of the nuclear equation of state and contribute to a more unified understanding of dense matter in both terrestrial experiments and astrophysical environments.

Relativistic Vorticity in the Quark-Gluon Plasma: Generation Symmetries, Explosive Dilution, and Azimuthal Spin Alignment

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.03716v2 Announce Type: replace Abstract: This article provides a self-contained bridge between classical vortex dynamics and the relativistic, subatomic domain of the Quark-Gluon Plasma (QGP) produced in ultra-relativistic heavy-ion collisions. While the QGP is widely studied for its near-perfect fluidity, we focus on its role as the most vortical medium in the Universe ($\omega \sim 10^{22}\text{ s}^{-1}$). The originality of our approach lies in isolating the explicit physical competition between non-linear vortex stretching and violent relativistic volumetric dilatation. By solving the covariant transport equations and tracking the comoving enstrophy density, we demonstrate that the explosive kinematics of the QGP provide an innate geometric shield that naturally regularizes the continuous flow, suppressing the self-amplification of vortex tubes before any microscopic viscosity is required. Furthermore, we connect this expansion phase back to the highly non-equilibrium initial state. We quantitatively predict that under a peripheral dipole initial topology, the global mid-rapidity hyperon polarization vanishes ($P_\Lambda \lesssim 10^{-4}$), establishing that the definitive signature of the QGP's rotation must be sought in azimuthal differential measurements within the LHC and RHIC experimental programs.

How Lorentz boosts reshape relaxation spectra

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2601.03081v2 Announce Type: replace-cross Abstract: In relativity, relaxation processes are often assumed to undergo time dilation under Lorentz boosts. We show that this intuition fails generically. Due to relativity of simultaneity, Lorentz boosts can split a single relaxation mode into a continuum of excitations, with a width set by the maximal signal propagation speed. Focusing on linearized relativistic (kinetic or rheological) theories with an Onsager-type symmetry, we derive rigorous bounds on relaxation spectra in arbitrary inertial frames, expressed solely in terms of rest-frame spectral data at zero wavenumber. As a consequence, non-hydrodynamic gaps, maximal relaxation rates, and the convergence radii of hydrodynamic modes obey nontrivial Lorentz-covariant constraints. These results provide a unified framework for understanding how relativity constrains relaxation dynamics in many-body systems.

Exploring Nucleon Structure and the Proton Mass Problem through Holographic QCD

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2603.04794v2 Announce Type: replace-cross Abstract: Understanding the internal structure of the proton-including the distributions of quarks and gluons and their contributions to proton properties such as mass-remains a central challenge in quantum chromodynamics (QCD). While quark generalized parton distributions (GPDs) have been studied extensively, a unified approach that simultaneously extracts quark parton distribution functions (PDFs), gravitational form factors (GFFs), and gluon GPDs from experimental constraints is still lacking. Moreover, the role of gluons in proton mass generation, particularly through the trace anomaly mechanism, requires deeper theoretical and phenomenological exploration. In this study, we begin by extracting quark GPDs in protons using a parameterization method based on the electromagnetic form factors provided by Light-Front Holographic QCD (LFHQCD), from which we derive both quark PDFs and their GFFs. We then extend this approach to model gluon GPDs. Our calculations show consistency with experimental data and lattice QCD results and successfully reproduce soft Pomeron behavior. Furthermore, we investigate near-threshold $J/\psi$ production using gauge/string duality to quantify the contribution of the trace anomaly to the proton mass. Our results demonstrate that the parameterization method provides a consistent framework for describing both quark and gluon structure, bridging GPDs, PDFs, and GFFs. The analysis of $J/\psi$ production confirms that the trace anomaly contributes significantly ($\sim 24\%$) to the proton mass, with the calculated cross-section dependence on momentum transfer $t$ in agreement with experimental observations. This work advances the understanding of proton structure by integrating quark and gluon degrees of freedom and elucidating the origin of proton mass within QCD.

Electromagnetic structure of Bc and heavy quarkonia in the light-front quark model

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2603.13819v2 Announce Type: replace-cross Abstract: We investigate the electromagnetic structure of heavy quarkonia and the $B_c$ meson within the light-front quark model (LFQM) to better understand the internal spatial charge distributions and QCD dynamics of heavy mesons. The light-front wave functions (LFWFs) are obtained using a variational approach with a few set of harmonic oscillator basis functions, providing a flexible yet tractable description of the bound-state dynamics. Using these LFWFs, we compute the electromagnetic form factors and compare our results with available lattice QCD data and other model calculations. Our results are roughly consistent with previous model predictions, showing that the electromagnetic radii of the $2S$ and $3S$ states are approximately 1.5 times and 1.9 times larger than those of their corresponding $1S$ states, reflecting the expected growth of spatial size in radial excitations.

Transverse energy-momentum tensor distributions in polarized nucleons

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2604.07616v2 Announce Type: replace-cross Abstract: We complete our study of the relativistic spatial distributions of the energy-momentum tensor inside polarized nucleons within the quantum phase-space formalism. In the present work, we focus on the components of the energy-momentum tensor involving at least one transverse index. We also explore the multipole structure of the transverse distributions in a moving nucleon. In the infinite-momentum frame, we show that the formalism reproduces the standard light-front distributions, including those with a ``bad'' component, and explains the origin of their structure.

Effective Color Dipole Approach to Color Transparency in $\rho^0$ Electroproduction

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.00566v3 Announce Type: replace-cross Abstract: We investigate nuclear transparency in exclusive $\rho^0$ electroproduction on $^{12}$C and $^{56}$Fe nuclei within a multi-channel final-state interaction (FSI) framework that explicitly incorporates the kinematic decay length effect (DLE) arising from the short-lived $\rho^0\to\pi^+\pi^-$ decay. The purely kinematic and nuclear mechanisms prove insufficient to account for the CLAS data: the DLE alone cannot generate the observed $Q^2$-dependent enhancement, and the inclusion of nuclear shadowing further deepens the disagreement, so that a compensating reduction of the in-medium attenuation -- the hallmark of color transparency (CT) -- is required. To incorporate the color dynamics of the initially compact $q\bar{q}$ configuration, we replace the empirical Quantum Diffusion Model (QDM) ansatz for the initial interaction cross section $\sigma_h(Q^2)$ of the point-like configuration (PLC) by an effective Color Dipole Model (CDM) boundary condition, evaluated through a normalized dipole-weighted $\gamma^*\to\rho^0$ transition overlap. Combined with the standard linear QDM transport at an effective in-medium expansion scale $\Delta m^2 = 0.3$~GeV$^2$, the CDM boundary condition reproduces both the magnitude and the $Q^2$ dependence of the data for both targets. A $\chi^2$ analysis quantifies the pronounced separation between the non-CT and CT-based descriptions and thereby supports the onset of color transparency in the $\rho^0$ channel beyond what kinematic decay-length effects can accommodate.

A New Low $Q^2$ Measurement of the Proton's $g_1$ Spin Structure Function from Longitudinal & Transverse Polarized Data

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.05741v1 Announce Type: new Abstract: The proton's spin structure has proven to be far more complicated than was originally believed, and has been the subject of a number of experimental investigations. %Early measurements of the proton's spin structure function $g_1$ showed that the proton does not solely derive its spin from the spins of its quarks, starting the `proton spin crisis'. Of particular interest are the spin structure functions $g_1$ and $g_2$, which can be used to generate moments to directly compare experimental results to Chiral Perturbation Theory and other theories of Quantum Chromodynamics (QCD). The proton's $g_1$ structure function has been the subject of two other recent low momentum transfer experiments, but there are currently no published low momentum transfer measurements which collected data on the proton structure functions using both a longitudinally-polarized and a transversely-polarized target at the same kinematics. In this paper, we present the longitudinally polarized results of the Jefferson Lab E08-027 experiment, along with linked moments which combine this new result with the previously published transversely-polarized data from the same experiment. These results provide a proton $g_1$ extraction measured with very high precision across the resonance region, and provide new information on the value of $g_1$ dependent sum rules and moments.

Gamma Backgrounds for Experiments at the High Flux Isotope Reactor

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2607.05834v1 Announce Type: cross Abstract: This article describes the deployment of a germanium detector at Oak Ridge National Lab's High Flux Isotope Reactor (HFIR) for the purpose of understanding the energy and spatial distribution of the gamma field in the experiment hall where the Precision Reactor Oscillation and Spectrum Experiment (PROSPECT) took data and future neutrino experiments could be located. The sources from both the reactor and the neutron beamlines are described in detail, along with their temporal variations due to reactor power and their spatial variations due to the geometry of the beamlines and building materials in the vicinity. Additionally, a shielding study was performed to assess the amount that backgrounds in tens of keV range can be mitigated. This work helps inform backgrounds for future experiments at reactors such as IBD-based neutrino measurements and CEvNS measurements.

The Silicon Tracking System of the E16 experiment at J-PARC: construction, installation and commissioning in beam test experiments

Wed, 08 Jul 2026 00:00:00 -0400

arXiv:2606.19400v2 Announce Type: replace-cross Abstract: The J-PARC E16 experiment aims to search for signatures of chiral symmetry restoration. It studies in-medium modifications of vector mesons that decay via the dielectron channel. The measurements use a high-intensity 30 GeV proton beam with C and Cu targets at rates up to 10 MHz. To achieve this, the experiment upgrades its tracking, by introducing innermost detector modules constructed with the same technology and procedures as the modules of the Silicon Tracking System (STS) of the Compressed Baryonic Matter (CBM) experiment at Facility for Antiproton and Ion Research (FAIR). A total of 15 modules were assembled, tested, characterized and then installed in the E16 detector setup. The detector was commissioned in a beam test experiment at Tsukuba, where the detector modules could be exposed to a 3 GeV electron beam. In preparation for the beam test the modules were characterized and calibrated, and performance studies were accomplished to assess the quality of the setup. During beamtime, three modules were operated and illuminated in two planes by the electron beam. This paper presents the results of the construction, characterization, commissioning, and operation of the E16-STS modules in beam test experiments.

Steering the dynamics by controlling the temporal interaction network

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.04998v1 Announce Type: new Abstract: Many real-world coupled dynamical systems have the interaction structure and strength that evolve or adapt over time. Here, we investigate how one can control the state of a system by tuning its temporal interaction network. We present a framework based on nonlinear optimal control, where one has control over the coupling matrix of a dynamical system. We show how to obtain the gradient of the Lagrangian function of the system using the adjoint method. We then focus on a linear time-variant system for which we illustrate the framework. Finally, we explore how the states at the nodes can be steered to target trajectories, by controlling the coupling matrix, imposing various constraint on its structure. The workflow presented here can be leveraged to steer the dynamics of systems with artificial or engineered interaction that is tunable.

From graphons to real-world networks: kinetic opinion dynamics under selective media influence

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.02821v1 Announce Type: cross Abstract: We propose a kinetic model of opinion dynamics under selective media influence on both graphon-based and real-world networks. The media action, inspired by Hallin's theory of spheres, is incorporated through a model predictive control strategy designed to steer agents' opinions toward a desired target opinion. For the resulting Boltzmann-type description, we analyse the evolution of the moments and, in the quasi-invariant interaction limit, derive a Fokker--Planck-type equation together with a characterisation of its stationary states. We also prove exponential convergence to equilibrium in the Fourier metric. Numerical experiments are performed on networks generated by a Gaussian graphon and on real-world, single-issue Twitter networks, allowing us to investigate the role of control and interaction parameters, as well as the impact of the subset of agents subject to media influence. Using real-world social networks data to initialise opinions and infer the interaction structure, we then compare the dynamics obtained on the original networks with those produced by Gaussian graphons fitted to their adjacency matrices, thereby assessing the descriptive power of the graphon approach for real-world opinion dynamics.

Thermodynamic efficiency of self-organisation in nonequilibrium steady states

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2605.04508v2 Announce Type: replace Abstract: Active matter generates order or patterns through nonequilibrium dynamics. An open research challenge is to determine how efficiently a nonequilibrium self-organising system can convert consumed energy into macroscopic order. We study an information-theoretic quantity that directly addresses this challenge by estimating the entropy reduction induced by a small control-parameter perturbation, relative to the generalised work required for the perturbation. This quantity has previously been considered mainly in an equilibrium or near-equilibrium context, and here we extend this framework and apply it to two nonequilibrium self-organising systems: persistent and active Ising models. We observe that the thermodynamic efficiency of nonequilibrium systems maximises at phase transitions, as in equilibrium systems. Furthermore, we compare thermodynamic efficiency and inferential efficiency across control parameters. While these two quantities are equal in equilibrium as a consequence of the fluctuation-dissipation theorem, we report that they diverge out of equilibrium, and the gap serves as a phenomenological signature of broken detailed balance.

An Isochron-Free Framework for Phase Reduction and Coupling Inference

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2606.25892v2 Announce Type: replace Abstract: Phase description provides a compact and powerful framework for analyzing synchronization dynamics in weakly coupled limit-cycle oscillators. While its classical formulation relies on the asymptotic phase defined by isochrons, reconstructing isochrons from observed trajectories is often challenging for complex models and real-world systems. Here we develop an isochron-free framework based on a readily computable generalized phase, such as the polar angle computed from observed trajectories. We theoretically show that, under near-uniform rotation of the generalized phase and sufficiently stable amplitude dynamics, a one-period stroboscopic description yields a closed circle map. The interaction term of the resulting circle map coincides, to leading order, with the phase coupling function obtained from the conventional phase reduction. Based on this circle map, we propose a method to infer coupling from oscillatory time series. The method is validated using synthetic data from van der Pol oscillators. Our framework broadens the applicability of phase reduction and provides a theoretically grounded method for coupling inference from oscillatory data.

Flocking phase transition and threat responses in bio-inspired autonomous drone swarms

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2512.21196v2 Announce Type: replace-cross Abstract: Collective motion inspired by animal groups offers powerful design principles for autonomous aerial swarms. We present a bio-inspired 3D flocking algorithm in which each drone interacts only with a minimal set of influential neighbors, relying solely on local alignment and attraction cues. By systematically tuning these two interaction gains, we map a phase diagram revealing sharp transitions between swarming and schooling, as well as a critical region where susceptibility, polarization fluctuations, and reorganization capacity peak. Outdoor experiments with a swarm of ten drones, combined with simulations using a calibrated flight-dynamics model, show that operating near this transition enhances responsiveness to external disturbances. When confronted with an intruder, the swarm performs rapid collective turns, transient expansions, and reliably recovers high alignment within seconds. These results demonstrate that minimal local-interaction rules are sufficient to generate multiple collective phases and that simple gain modulation offers an efficient mechanism to adjust stability, flexibility, and resilience in drone swarms.

Berry Picking: Random Wave Chaos Hierarchy for BPS Microstate Geometries

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.03434v1 Announce Type: cross Abstract: We estimate the strength of chaos of probe waves and probe geodesics in different smooth supergravity backgrounds of decreasing supersymmetry and/or increasing length of the AdS throat in the interior (LLM geometry, supertubes, superstrata). We find that the wave chaos becomes stronger and stronger with less supersymetry and longer throats; in other words, chaos becomes stronger as we approach black hole solutions. Geodesic motion shows the opposite trend, becoming more and more regular. Testing the wave chaos by its compliance with the Berry random wave hypothesis and the geodesic chaos by computing Poincare sections, we explain the dichotomy between wave and geodesic motion by the existence of stable periodic orbits inside long throats while the overall measure of KAM tori decreases. Computing the Renyi entropies for the dual CFT states in the weak coupling regime, we show that they do not have such universal trends and the complexity depends on the specifics of the state rather than just the amount of supersymmetry and throat length. We conclude that the hierarchy of BPS chaos works differently in the bulk and in field theory, and in either case cannot be simply extrapolated to black holes.

Diffusion learning reveals viable parameter manifolds and compensation geometry in biological dynamical systems

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.03671v1 Announce Type: cross Abstract: Models of complex systems often have many parameters, yet are constrained by far fewer experimentally accessible observables: similar activity can emerge from coordinated parameter changes. We formalize these compatible parameter sets as \emph{viable parameter manifolds}: the inverse images of a system's target dynamical behaviors under a parameter-to-feature map. The relevant codimension is not the number of reported features, but the effective rank of that map at the target scale. Co-varying features lower the codimension, while poor conditioning, high curvature, or regime mixing degrade learnability. We train conditional score-based diffusion models on simulated parameter--feature pairs and use them as amortized samplers of prior-weighted viable sets. In the Lorenz system, scalar trajectory statistics generate thin viable sheets, and two-feature conditioning localizes a transition-adjacent corridor. In the Izhikevich neuron model, four firing descriptors lie close to a nearly two-dimensional family of features, and the learned inverse images reveal distinct regular and irregular compensation geometries. In a recent ODE reduction of finite spiking networks, the same framework reveals excitatory--inhibitory compensation, timescale--coupling tradeoffs, and input-dependent viable manifolds across 4--12 parameter dimensions. In this view, robustness, compensation, and hidden parameter dependencies are organized as inverse geometry, with diffusion models providing practical tools for sampling, visualizing, and interrogating that geometry.

Classical and Quantum Properties of the Spin-Boson Dicke Model: Chaos, Localization, and Scarring

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2405.20381v2 Announce Type: replace-cross Abstract: This review article describes major developments associated with the Dicke model, from its introduction in the 1950s to explain the transition from a normal to a superradiant phase to its modern applications in quantum many-body physics. Over the decades, this interacting spin-boson model has played a central role in the study of collective light-matter interactions, chaos, and quantum phase transitions. We focus on properties and phenomena that are best understood when seen from both the classical and quantum perspectives, with particular emphasis on the emergence of chaos, localization, and scarring. While our primary emphasis is on the isolated model, we also discuss recent advances in the open Dicke model, where environmental couplings are needed for describing realistic experimental platforms and exploring new regimes of quantum dynamics.

When is a System Discoverable from Data? Discovery Requires Chaos

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2511.08860v2 Announce Type: replace-cross Abstract: The deep learning revolution has spurred a rise in advances of using AI in sciences. Within physical sciences the main focus has been on discovery of dynamical systems from observational data. Yet the reliability of learned surrogates and symbolic models is often undermined by the fundamental problem of non-uniqueness. The resulting models may fit the available data perfectly, but lack genuine predictive power. This raises the question: under what conditions can the systems governing equations be uniquely identified from a finite set of observations? We show, counter-intuitively, that chaos, typically associated with unpredictability, is crucial for ensuring a system is discoverable in the space of continuous or analytic functions. The prevalence of chaotic systems in benchmark datasets may have inadvertently obscured this fundamental limitation. More concretely, we show that systems chaotic on their entire domain are discoverable from a single trajectory within the space of continuous functions, and systems chaotic on a strange attractor are analytically discoverable under a geometric condition on the attractor. As a consequence, we demonstrate for the first time that the classical Lorenz system is analytically discoverable. Moreover, we establish that analytic discoverability is impossible in the presence of first integrals, common in real-world systems. These findings help explain the success of data-driven methods in inherently chaotic domains like weather forecasting, while revealing a significant challenge for engineering applications like digital twins, where stable, predictable behavior is desired. For these non-chaotic systems, we find that while trajectory data alone is insufficient, certain prior physical knowledge can help ensure discoverability. These findings warrant a critical re-evaluation of the fundamental assumptions underpinning purely data-driven discovery.

Linear Response and Optimal Fingerprinting for Nonautonomous Systems

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2602.08022v3 Announce Type: replace-cross Abstract: We provide a link between response theory, pullback measures, and optimal fingerprinting method that paves the way for a) predicting the impact of acting forcings on time-dependent systems and b) attributing observed anomalies to acting forcings when the reference state is not time-independent. We derive formulas for linear response theory for time-dependent Markov chains and diffusion processes. We discuss existence, uniqueness, and differentiability of the equivariant measure under general (not necessarily slow or periodic) perturbations of the transition kernels. Our results allow for extending the theory of optimal fingerprinting for detection and attribution of climate change (or change in any complex system) when the background state is time-dependent amd when the optimal solution is sought for multiple time slices at the same time. We provide numerical support for the findings by applying our theory to a modified version of the Ghil-Sellers energy balance model. We verify the precision of response theory - even in a coarse-grained setting - in predicting the impact of increasing CO$_2$ concentration on the temperature field. Additionally, we show that the optimal fingerprinting method developed here is capable to attribute the climate change signal to multiple acting forcings across a vast time horizon.

Beyond the Largest Lyapunov Exponent: Entropy-Based Diagnostics of Chaos in Henon-Heiles and N-Body Dynamics

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2603.24675v2 Announce Type: replace-cross Abstract: The largest Lyapunov exponent is widely used to diagnose chaos in gravitational dynamics, but in mixed phase spaces and finite-N systems it does not always provide a complete description of orbital complexity and phase-space transport. Entropy-based diagnostics may offer a complementary perspective. We investigate whether trajectory-based information entropy can provide a useful diagnostic of chaos in gravitational systems and how it relates to the largest Lyapunov exponent as a function of orbital energy and of the number of degrees of freedom. We computed the largest Lyapunov exponent and a coarse-grained Shannon entropy for ensembles of trajectories in the Henon-Heiles potential and for test-particle orbits in live N-body realizations of a Plummer model. We then compared the dependence of both quantities on orbital energy and, for the N-body case, on particle number. In the Henon-Heiles system, the Shannon entropy follows the transition from weak to widespread chaos and exhibits an energy dependence that closely mirrors that of the largest Lyapunov exponent. For test-particle orbits in live N-body potentials, both diagnostics indicate stronger chaos for more tightly bound trajectories. However, their dependence on N differs: the largest Lyapunov exponent remains nearly constant over the explored range of particle numbers, whereas the Shannon entropy decreases monotonically as N increases. These results show that the information entropy can complement the largest Lyapunov exponent and may better capture changes in global phase-space mixing, especially in systems where the leading Lyapunov exponent alone is not sufficiently informative. It therefore provides a promising alternative for diagnosing chaos when tangent-space dynamics is unavailable or computationally expensive, and it is naturally suited to systems with densely sampled trajectories, such as minor bodies in the Solar System.

Diagnosing the conditional-mean barrier in scientific machine-learning surrogates

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2605.28076v3 Announce Type: replace-cross Abstract: Many prediction tasks in computational science and engineering become one-to-many after coarse graining and partial observation. In such settings, deterministic surrogates trained by squared loss may learn a well-defined mathematical object, the conditional mean, while still missing the task-relevant variability in the underlying conditional law. In this work, we formulate this limitation as the conditional-mean barrier and develop a diagnostic framework for identifying it in fitted scientific machine-learning surrogates. The framework combines residual-feature orthogonality and effect-size diagnostics to distinguish deterministic underfitting from irreducible conditional variability. We also make explicit a simple consequence of paired squared loss: stochastic outputs do not by themselves overcome the barrier, because the objective penalizes model variance and drives the predictor back to the conditional mean. The diagnosis therefore yields a modeling prescription: when residual variability matters, the loss must score richer features of the conditional law rather than a point prediction. Reproducible numerical studies on a controlled two-branch law and a two-scale Lorenz-96 closure problem show how the diagnostic identifies the barrier, how deterministic closures can suppress collective fluctuation statistics in rollout, and how a minimal likelihood-based stochastic-scale model can recover substantially more variability.

On the Nonlinear Sensitivity of Phononic Frequency Combs to Physical Perturbations

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.03837v1 Announce Type: new Abstract: Phononic frequency combs offer a rich platform for nonlinear sensing, yet how their observable properties respond to changes in physical parameters remains poorly understood. Using a reduced two-mode autoparametric resonance model, we investigate how primary and secondary detuning, drive amplitude, and relative damping jointly shape amplitude and frequency sensitivity across the nonlinear parameter space. We find that sensitivity is far from uniform: primary detuning shifts the comb response smoothly, secondary detuning produces sharply localized transitions near resonance manifolds, and drive amplitude concentrates peak sensitivity close to the activation threshold rather than deep within the comb state. The relative damping redistributes energy continuously between modes without introducing discontinuities. The nonlinear sensitivity of amplitude and frequency observables across all parameters points to a common physical origin in autoparametric resonance, nonlinear saturation, and coupling-induced synchronization, offering a coherent basis for designing nonlinear sensing platforms with deliberate, parameter-aware sensitivity engineering.

Localized spatiotemporal reaction-diffusion patterns on a line and a disk arising from a subcritical finite wavenumber Hopf instability

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2603.15161v2 Announce Type: replace Abstract: Spatiotemporal localized and extended structures associated with a subcritical finite wavenumber Hopf bifurcation are studied in the Purwins model (a three-variable FitzHugh-Nagumo version). Steady and time-dependent numerical continuation procedures are used to investigate snaking behavior of localized standing and traveling waves on the real line, and the results are corroborated using weakly nonlinear theory. The results shed light on the origin of so-called jumping oscillons and the organization of a nontypical homoclinic snaking structure of traveling pulses. The computations are extended to moderate size disks and used to identify wall-attached spots that travel along the disk boundary as well as wall-attached spots that oscillate in place and wall-attached jumping oscillons. The one-dimensional results are shown to be useful in interpreting the two-dimensional results. Domain-filling and mixed structures are also studied, demonstrating the variety of extended and localized states that emerge in two-space dimensions, ranging from periodic to disordered. The latter are potentially important for observations of waves in far-from-equilibrium media, such as those often observed in cell biology.

Generalized FDNF fuzzification of elementary cellular automata and its nonlinear pattern dynamics

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2510.01629v3 Announce Type: replace-cross Abstract: Fuzzy disjunctive normal form (FDNF) gives the canonical multi-affine extension of an elementary cellular automaton (ECA) rule to the unit cube. Although it preserves the Boolean rule on binary states, its multi-affine structure can smooth high-contrast CA patterns and restrict continuous-state dynamics. We introduce generalized FDNF rules \[ \widetilde f_k^{g,u,v,w}(x,y,z) = g\left(f_k(u(x),v(y),w(z))\right), \] where the transformations $g,u,v,w: [0,1] \to [0,1]$ fix the endpoints. The identity maps recover ordinary FDNF, while threshold-like, discontinuous, non-monotone, and expanding choices yield rule-preserving fuzzy ECAs. We demonstrate, in representative rules, that the transformation shape strongly affects pattern dynamics: threshold-like maps promote ECA-like pattern recovery, parameter deformations interpolate toward FDNF-like smoothing, and discontinuities induce gap-generated regimes. Pattern changes are summarized by contrast, fuzziness, and a finite-resolution participation-type support exponent. In three-cell systems, an expanding non-monotone transformation yields stable period-six cycles for rule 210, verified by interval arithmetic, coexisting with an expanding invariant line set; rules 51 and 85 inherit one-dimensional expanding dynamics. The framework provides a rule-preserving bridge from Boolean cellular automata to fuzzy and continuous-state nonlinear dynamics.

Maximal Densities of Finite-Gap Solutions of the Sine-Gordon Equation

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.03555v1 Announce Type: new Abstract: We establish a sharp upper bound on the densities of finite-gap solutions of the sine-Gordon equation. The bound is derived directly from the finite-dimensional hierarchy, without explicit integration of the finite-gap solutions. The maximal density is determined by the roots of the invariant polynomial. An analogous sharp upper bound is established for a bounded class of finite-gap solutions of the sinh-Gordon equation.

Integrable full discretization of the multi-component short pulse equation

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.04756v1 Announce Type: new Abstract: We propose a new formulation of the multi-component short pulse (MCSP) equation that includes the coupled complex short pulse (CCSP) equation as a reduction. Using Hirota's bilinear method, we construct its $N$-soliton solutions in Pfaffian form. We then derive integrable semi-discrete and fully discrete analogues of the MCSP equation admitting Pfaffian $N$-soliton solutions. The resulting fully discrete system provides a practical self-adaptive moving mesh scheme for numerical simulations. For the parameter sets considered, numerical simulations demonstrate excellent agreement between the numerical and exact solutions, confirming the robustness and high accuracy of the proposed scheme.

Wei-Norman approach for non-Hermitian driven spin-$S$ systems and its application to defect freezing

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.04075v1 Announce Type: cross Abstract: In the theoretical study of nonequilibrium non-Hermitian systems, obtaining exact analytical solutions for their nonadiabatic dynamics is highly desirable yet often challenging. In this work, we identify a class of non-Hermitian quantum systems where this difficulty can be substantially reduced. Employing the Wei-Norman approach, we show that for a spin-$S$ subject to a general non-Hermitian time-dependent drive, the matrix elements of the evolution operator can be expressed in closed analytical forms (via Jacobi polynomials) in terms of the corresponding spin-$1/2$ model. This approach is straightforward and accessible to nonspecialists in Lie algebra. As an application, we investigate a specific nonequilibrium non-Hermitian phenomenon known as defect freezing, i.e., the existence of excitations in the adiabatic limit, in spin-$S$ extensions of the $\mathcal{PT}$-symmetric Su-Schrieffer-Heeger model under linear quenches. We derive exact analytical expressions for the momentum-resolved excitation probabilities and the total excitation densities. Our results reveal that defect freezing occurs exclusively in momentum sectors that traverse the $\mathcal{PT}$-symmetry-broken region -- and thus pass through a pair of higher-order exceptional points (EPs) -- during the quench; notably, the excitation density exhibits a singularity at a critical value of the non-Hermiticity parameter. This work enriches the analytical toolkit for nonadiabatic dynamics in multi-level non-Hermitian systems and provides quantitative, testable predictions for defect freezing across higher-order EPs, possibly accessible on platforms such as electric circuit networks and photonic lattices.

A Lax representation, symmetries, and conservation laws for the three-dimensional Euler--Helmholtz equations

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2409.05752v2 Announce Type: replace Abstract: We study the three-dimensional Euler--Helmholtz equations for an inviscid incompressible fluid. Under the Poincar{\'{e}} lemma assumption, the incompressibility condition is resolved by introducing a vector potential, leading to a vorticity-type reformulation of the system. The main result is the construction of a Lax representation for this system, revealing hidden integrable structures and providing a differential covering framework for its analysis. We compute the Lie algebra of point symmetries and find the zeroth-order cosymmetries together with the associated local conservation laws. Using the Lax representation, we construct a shadow of cosymmetry in the corresponding covering and, via the construction of canonical conservation law, derive an infinite hierarchy of nonlocal conservation laws. Finally, we establish a B\"acklund transformation between tangent and cotangent coverings and describe its action on symmetries and cosymmetries in terms of pseudopotentials, highlighting the interplay between integrability, symmetry, and conservation laws.

Analytic General Solution of the Riccati equation

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2510.19297v5 Announce Type: replace Abstract: A sufficient and necessary condition for integrability of the Riccati equation, which is the simplest form of nonlinear ordinary differential equation, is established by using the elementary quadrature method. Based on this condition, the analytic general solution including free variable (parameter) and the associated entangled functions are provided, which can be extended to second-order linear ordinary differential equation. These results may provide a mathematical criterion for modern physics as well as for nonlinear phenomena in various fields.

Tritronqu\'ee Painlev\'e II asymptotics for the focusing nonlinear Schr\"odinger equation with nonzero boundary conditions

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2606.29156v2 Announce Type: replace Abstract: We study the long-time asymptotics of the focusing nonlinear Schr\"odinger equation with nonzero boundary conditions in the transition regions between the plane-wave and modulated elliptic-wave regimes. Biondini and Mantzavinos showed that, away from the transition curves $x=\pm 4\sqrt{2}\,q_o t$, the $(x,t)$-half-plane decomposes, to leading order, into two plane-wave regions and a central region described by slowly modulated elliptic oscillations. However, their asymptotic formulae are not uniform near the boundaries separating these regions. The purpose of this paper is to resolve this missing boundary layer. Using a double-scaling nonlinear steepest descent analysis of the associated Riemann--Hilbert problem, we show that the leading term in each transition region is still a plane wave, while the first nontrivial correction is of order $t^{-1/3}$. The coefficient of this correction is expressed in terms of a distinguished tritronqu\'ee solution of an inhomogeneous Painlev\'e-II equation. This Painlev\'e-II tritronqu\'ee structure is also known to appear in the asymptotic analysis of rogue waves of infinite order.

CUORE Data Release for ML Applications: Pulse Shape Analysis Dataset

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.02548v1 Announce Type: cross Abstract: We present a public dataset from the CUORE (Cryogenic Underground Observatory for Rare Events) experiment, designed to support the development and benchmarking of Artificial Intelligence and Machine Learning (AI/ML) algorithms for cryogenic calorimeter data analysis. CUORE uses TeO$_2$ cryogenic calorimeters to measure particle energy depositions as thermal fluctuations. This dataset contains thermal pulses measured during calibration data taking. Each data point is provided as a one-dimensional, time-series array corresponding to a thermal pulse, accompanied by a binary classification label to distinguish between single-pulse events and pile-up events with two or more pulses; pulse normalization parameters and relevant metadata are also included, with all data stored in HDF5 format. This data release enables the testing of supervised learning approaches to pulse shape analysis, pile-up identification, and related tasks in the context of rare-event searches with cryogenic calorimeters.

A New High-Intensity Source for Ultracold Neutrons

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.03033v1 Announce Type: cross Abstract: The TRIUMF UltraCold Advanced Neutron (TUCAN) collaboration has completed a new superthermal source for ultracold neutrons (UCNs) at TRIUMF. It uses neutrons from a spallation target driven by TRIUMF's main cyclotron. Heavy water and liquid deuterium serve as neutron moderators, and inelastic scattering inside superfluid $^4$He at around $1.1$~K slows the neutrons down to become ultracold. During commissioning runs with the completed source, including the deuterium moderator, up to $1.34(1)\times 10^7$ UCNs were detected in the experimental area after irradiating the target and accumulating UCNs in the source for $60$~s. Up to $6.75(3) \times 10^5$ UCN/s were detected during continuous operation, more than at any other source in the world.

Quantum interference effects enhanced in $\pi^+p$ femtoscopic correlation functions

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.04351v1 Announce Type: cross Abstract: We present a comprehensive analysis of the $\pi^+p$ femtoscopic correlation functions measured by the ALICE Collaboration in high-multiplicity $pp$ collisions at $\sqrt{s}=13$ TeV. Using the Koonin-Pratt formula with a Gaussian source and data-driven $\pi N$ partial-wave amplitudes, we account for the contributions from $\pi^+p$ scattering and $\Delta(1232)^{++}$-decay, thereby successfully reproducing the measured data and their transverse-mass ($m_T$) dependence. The scattering contribution yields a peak near the relative momentum $k\approx140$ MeV/$c$, whereas the decay contribution peaks around $k\approx220$ MeV/$c$. The observed correlation peak results from a weighted sum of the two contributions, with $m_T$-dependent relative weights. We find that the 140 MeV/$c$ peak originates from quantum interference between the incident and scattered waves-a mechanism previously unnoticed in femtoscopic studies. This finding resolves the peak-shift puzzle in $\pi^+p$ correlations and provides a novel perspective for quantum interference effects in femtoscopy.

$S$ matrices of elastic $n$-$^{16}$O scattering at low energies in cluster effective field theory

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.04836v1 Announce Type: cross Abstract: Elastic $n$-$^{16}$O scattering at low energies is studied in the framework of cluster effective field theory. An evaluated data set of the total cross section of elastic $n$-$^{16}$O scattering at neutron energy, $0\le E_n\le 4$~MeV, is adopted from Evaluated Nuclear Data File (ENDF/B-VIII.0). We derive an expression for the $S$ matrices of the elastic scattering for seven spin-partial wave channels, $lj=s_{1/2}$, $p_{1/2}$, $p_{3/2}$, $d_{3/2}$, $d_{5/2}$, $f_{5/2}$, $f_{7/2}$, including one excited state and nineteen resonant states of $^{17}$O. Thirty-four parameters of the theory are fitted to the ENDF data, and we find that a plotted line, by using the fitted parameters, reproduces the ENDF data well. We discuss the uncertainties that may appear in the present approach from the fitted parameters of the resonant states with widths, larger than $\Gamma = 90$~keV. We also discuss the implications of the fitted values of energies and widths of the resonant states in the estimate of the astrophysical $S$ factor of $^{13}$C($\alpha$,$n$)$^{16}$O reaction at stellar energies.

High-precision ab initio calculations of nuclear binding energies: Tin isotopes from dripline to dripline

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.05086v1 Announce Type: cross Abstract: The location of the neutron drip line in tin isotopes has important consequences for our fundamental understanding of nuclear structure and nuclear forces as well as for astrophysical nucleosynthesis. Performing high-precision ab initio calculations of even-even tin isotopes from $N=50$ to $N=126$ based on chiral two- and three-nucleon interactions, the predicted drip-line location is found to be highly sensitive to the employed nuclear interactions and to exhibit tension with recent energy-density-functional predictions. On the neutron-deficient side, results are consistent with extrapolated two-neutron separation energies constrained by recent Penning-trap mass measurements.

Towards Quantum Simulation of Rotating Nuclei using Quantum Variational Algorithms

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2506.18059v3 Announce Type: replace-cross Abstract: Quantum variational algorithms (QVAs) are increasingly potent tools for simulating quantum many-body systems on noisy intermediate-scale quantum (NISQ) devices. This work examines the application of the Variational Quantum Eigensolver (VQE) to four progressively complex models based on the cranked Nilsson-Strutinsky (CNS) framework. By incorporating single-particle spacings, pairing correlations, and rotational cranking terms, we evaluate VQE performance against exact diagonalization (ED) benchmarks. We provide a systematic benchmarking of VQE across a hierarchy of CNS-inspired Hamiltonians, explicitly identifying where hardware-efficient ansatz succeed and fail, and introducing quantum information diagnostics, the entanglement spectrum and Quantum Fisher Information, as novel probes of the pairing-rotation. Our results demonstrate that with a properly optimised multi-restart warm-starting strategy, VQE achieves near-machine-precision convergence ($|\Delta E| < 10^{-4}$) across the full cranking frequency range $\omega \in [0,1.2]$ and we confirm that the same strategy reproduces an established $^{6}$He shell-model pairing benchmark, demonstrating that the RealAmplitudes ansatz is expressively sufficient for this problem class. The entanglement spectrum confirms the product-state character of the exact ground state throughout the pairing-rotation transition, while the Quantum Fisher Information identifies a finite-size precursor to the critical pair-breaking frequency. These results establish a systematic methodological baseline and provide a reproducible framework for the nuclear physics community.

High-Dimensional Unfolding in Large Backgrounds

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2507.06291v2 Announce Type: replace-cross Abstract: We propose new methodologies in multi-dimensional unfolding in dense environments, and show that incorporating auxiliary observables can significantly improve performance. Our approach builds on the ML-based OmniFold algorithm, which we extend to account for background, detector acceptance, efficiency, and uncertainties, enabling its application in high-luminosity and heavy-ion collision settings. We derive this algorithm and demonstrate its mathematical and numerical equivalence to expectation-maximization and Iterative Bayesian Unfolding (IBU). We illustrate our method with a realistic jet substructure analysis incorporating both large background and detector simulation. Our analysis includes up to 18 observables, leading to significantly improved performance in the unfolding. We propose a method that integrates calibration and unfolding into a single, consistent framework, and demonstrate enhanced performance relative to traditional methods. These developments lay the groundwork for robust, high-dimensional, ML-based unfolding and calibration in complex collider environments across a wide range of analyses.

Can Bose-Einstein condensates enhance radioactive decay?

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2510.21692v3 Announce Type: replace-cross Abstract: This paper lays out the principles of how Bose-Einstein condensates can modify radioactive decay. We highlight the challenges of many modes and short coherence times due to the $\approx$ MeV energies of the emitted radiation. Recent proposals for gamma ray and neutrino lasers claim that using a Bose-Einstein condensate as a source would solve these issues. We show that this is not the case, and the proposed experiments would have a gain of only $10^{-16}$ or smaller. We also analyze proposals for gamma ray lasers based on stimulated annihilation of positronium Bose-Einstein condensates.

Resolution-matched nuclear geometry and the nucleon-size ambiguity in relativistic heavy-ion collisions

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2602.18683v2 Announce Type: replace-cross Abstract: Nuclear structure theory provides point-nucleon densities, whereas high-energy nuclear collisions probe nuclei through finite-resolution hadronic interactions. This resolution mismatch becomes a physical ambiguity when point densities are embedded in Monte Carlo initial-state models with a finite transverse nucleon profile. A parameter intended to describe the effective interaction range can then also reshape the nuclear surface, blurring the separation between nuclear structure and collision dynamics. I show that this ambiguity can largely account for the strong nucleon-width dependence of the ${}^{208}$Pb+${}^{208}$Pb hadronic cross section ($\sigma_{\rm AA}$) reported in recent Bayesian analyses. Fixing the folded density that enters the Glauber phase shift removes this ambiguity at the level of nuclear geometry. The corrected cross section becomes nearly insensitive to a Gaussian nucleon width and instead probes the nuclear surface. Within a two-component estimate for ${}^{208}$Pb, the current experimental uncertainty of $\sigma_{\rm AA}$ translates into a broad neutron-skin interval, $\Delta r_{\rm np}\in[0,0.21]$ fm. These results reframe $\sigma_{\rm AA}$ as a surface-sensitive bridge between point-nucleon nuclear structure and finite-resolution high-energy initial conditions, rather than as a standalone nucleon-size observable. This establishes resolution matching as a necessary step for using relativistic heavy-ion collisions as quantitative probes of nuclear structure.

Multimodal Fragmentation of All-Heavy Pentaquarks: Uncertainty-Aware Predictions for Hadron Colliders

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2605.01539v2 Announce Type: replace-cross Abstract: We present an uncertainty-aware description of leading-power fragmentation for all-charm pentaquark states ($S$-wave $|cccc\bar{c}\rangle$) at hadron colliders. We construct a multimodal set of collinear fragmentation functions, PQ5Q1.1, incorporating both perturbative and nonperturbative uncertainties. Perturbative effects are estimated via missing higher-order variations (F-MHOUs), while the nonperturbative wave function is modeled through controlled modifications of its transverse-momentum structure (F-NPWF), consistently combined within a replica-like framework. The initial-scale input for constituent charm fragmentation is refined to describe both compact multiquark and diquark-driven production mechanisms. We employ the (sym)JETHAD interface to study NLL/NLO$^+$ semi-inclusive pentaquark-plus-jet production at the HL-LHC and future FCC. The bottom sector is left to future dedicated studies due to its enhanced sensitivity to nonperturbative modeling. Our results provide a flexible framework for uncertainty-controlled predictions, bridging exotic-hadron structure, heavy-flavor fragmentation, and high-energy QCD.

Spin-Selective Hadron Spectroscopy via Azimuthal Anisotropies from Entanglement-Enabled Spin Interference

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2606.16966v2 Announce Type: replace-cross Abstract: The $\pi^+\pi^-$ invariant mass spectrum above the $\rho^0(770)$ is rich with broad, overlapping resonances. Disentangling them, whether in photoproduction, ultra-peripheral heavy-ion collisions, or electroproduction, is a longstanding challenge for conventional partial-wave analysis. We show that the recently observed entanglement-enabled spin-interference effect in ultra-peripheral collisions provides a quantum-mechanical filter that resolves this ambiguity: the angular harmonics $A_n$ of the $\cos(n\Delta\phi)$ asymmetry, which are governed by selection rules in the spin of the interfering states. Specifically, overlap between two distinct spin-1 amplitudes leads to interference that populate $A_2$ alone, while overlap of a spin-1 amplitude with a spin-2 one generates $A_1$ and $A_3$. Utilizing ALICE data in the $1.0$--$1.4\,\mathrm{GeV} \; c^{-2}$ region, we demonstrate that two physically distinct hypotheses -- an additional spin-1 $\rho'(1450)$ (produced via photonuclear interactions) versus a spin-2 (photon-photon) $f_2(1270)$ state -- fit the invariant mass spectrum equally well but predict different $A_n$: identically zero $A_1$ and $A_3$ in the spin-1 case, versus pronounced peaks in the spin-2 case. This selection rule provides a new tool for hadronic spectroscopy in ultra-peripheral collisions and the first viable route to isolating the $\gamma\gamma\to\pi^+\pi^-$ continuum from the dominant photonuclear background, revealing a clean low-energy probe of non-perturbative QCD.

Circle of Alpha-Particle Cluster Shapes in Neon-20

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.03917v1 Announce Type: new Abstract: Quantum states of Neon-20 are generally agreed to lie in rotational-vibrational bands of a cluster of five alpha particles. However, more than one cluster shape has been proposed as dominant at low energy. As relative motion within a cluster is soft in certain directions, we investigate how the low-lying rotational bands of Neon-20 can arise from a circle of clusters connecting favoured shapes: a triangular bipyramid, a square pyramid, and a $D_{2d}$-symmetric distorted tetrahedron -- a twisted bow-tie. Motion around the circle extends the Berry pseudo-rotation that connects differently oriented bipyramids.

Global systematics and theoretical interpretation of $l$-forbidden $M1$ transitions in odd-$A$ nuclei

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.03970v1 Announce Type: new Abstract: The $l$-forbidden magnetic dipole ($M1$) transitions, characterized by a change in orbital angular momentum ($\Delta \ell = 2$), serve as sensitive probes of higher-order effects, including configuration mixing and meson-exchange currents. In this work, we present a comprehensive systematic study of all experimentally known $l$-forbidden $M1$ transitions, covering odd-$A$ nuclei with neutron numbers $27 \leq N \leq 126$. To interpret these global systematics, we apply a theoretical framework based on the relativistic Dirac wave function. This approach directly links the $l$-forbidden $M1$ transition amplitudes between pseudospin-partner orbitals to experimental single-particle magnetic moments. We perform a global comparison across isotopic chains by substituting unknown magnetic moments with rescaled Schmidt estimates. Focusing on dominant transition groups, including $p_{3/2} \rightarrow f_{5/2}$, $s_{1/2} \rightarrow d_{3/2}$, and $d_{5/2} \rightarrow g_{7/2}$, our analysis establishes a robust linear correlation between the transition amplitudes $\sqrt{B(M1)}$ and the corresponding empirical single-particle matrix elements $M_{\mathrm{sp}}$. The proportionality coefficient $\rho$ serves as an empirical measure of single-particle strength fragmentation and quantifies the role of configuration mixing in driving $l$-forbidden transitions across the nuclear chart.

Evaluation of U-235 and U-238 Fission Product Yields Using Bayesian Neural Networks: Comparison of Baseline and Physics-Informed Models

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.04148v1 Announce Type: new Abstract: U-235 and U-238 are fundamental materials in thermal and fast neutron breeding studies. Accurate evaluation of their fission product yields is of critical importance for advanced reactor design and nuclear waste management. In this work, a baseline Bayesian neural network model (BNN0) with two hidden layers of 20 neurons each was constructed. An improved model, BNN3, was developed by incorporating additional physics-informed features, namely the odd-even effect, beta-decay energy, and isospin, into the network inputs. Comparative analyses of the general distributions of the fission yields and isotopic chain structures demonstrate that BNN3 exhibits significantly improved reconstruction accuracy and consistency with the target cumulative fission-yield distributions. For 16 representative fission products, the energy-dependent yield predictions of BNN3 show better agreement with both experimental data and evaluated libraries, accompanied by noticeably narrower confidence intervals. These results indicate that the incorporation of relevant physical information improves the model's sensitivity to underlying fission mechanisms and enhances its capability to reproduce the systematic characteristics of cumulative fission-yield distributions. Together, these strategies contribute to more accurate and robust nuclear data modeling, providing a methodological foundation for the evaluation and development of next-generation nuclear data libraries.

An expanding spherical fireball model for light hadron production at RHIC ($\sqrt{s_{\rm NN}}=7.7$--$39$ GeV)

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.04191v1 Announce Type: new Abstract: We investigate the transverse momentum ($p_T$) spectra and rapidity distributions of the light hadrons $\pi^{\pm}$, $K^{\pm}$, $p$, and $\bar{p}$ produced in Au+Au collisions at RHIC for $\sqrt{s_{\rm NN}} = 7.7$--39 GeV and different collision centralities. The produced medium is modeled as an expanding spherical fireball, with the radial expansion velocity determined from the rate of increase of the fireball radius. The particle spectra are calculated using the Cooper--Frye freeze-out prescription with a local equilibrium distribution function and a blast-wave-like flow profile. The model parameters are fixed from the midrapidity $p_T$ spectra of pions at kinetic freeze-out for different centralities. The same parameters are then used for the other hadron species, with the kinetic freeze-out chemical potential as the only additional free parameter. The model provides a good description of the STAR collaboration data for the $p_{T}$ spectra of light hadrons and predicts Gaussian-like rapidity distributions over the considered energy range across different centralities.

Relativistic Hydrodynamics and Vorticity Dynamics in High-Energy Heavy-Ion Collisions: A Collective Flow Perspective

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.04273v1 Announce Type: new Abstract: This article provides a comprehensive overview of the application of relativistic fluid mechanics to describe the collective evolution of the Quark-Gluon Plasma (QGP) formed in ultra-relativistic heavy-ion collisions. We map out the chronological transformation of spatial eccentricities in the initial interaction volume into measurable anisotropic azimuthal momentum distributions, parameterized by the harmonic flow coefficients $v_n$. Utilizing multi-particle correlation techniques developed within the ATLAS experimental framework, we dissect the event-by-event fluctuations of the participant planes and evaluate non-linear hydrodynamic responses across higher harmonics. Furthermore, we embed local rotation fields into this continuous description by solving the covariant transport equations for subatomic vorticity. We demonstrate that while the Helmholtz-Kelvin theorem guarantees the topological conservation of vortex lines within the ideal medium, the collective multi-dimensional expansion forces a systematic 1/t power-law geometric dilution of the local rotational magnitude. Finally, we contrast different pre-equilibrium generation mechanisms and evaluate their final signatures on differential spin alignment observables.

A Phenomenological Extension for Microscopic Optical Potentials

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.05080v1 Announce Type: new Abstract: Microscopic optical potentials constructed from realistic nucleon-nucleon interactions via multiple-scattering theory provide a first-principles description of nucleon-nucleus scattering. Nevertheless, such approaches often neglect medium corrections beyond Pauli blocking and fail to fully capture higher-order scattering contributions, leading to systematic under-prediction of absorption and deficiencies in angular distributions at low and intermediate energies. In this work we introduce a phenomenological correction scheme with an energy-dependent term designed to mimic correlation effects, dispersive contributions, and multi-step scattering processes. The correction is implemented in a minimal form to preserve the predictive character of the underlying microscopic model, while enabling improved flexibility in describing experimental observables. Applications to proton and neutron elastic scattering on light-mass nuclei demonstrate that the modified potentials yield enhanced agreement with measured differential cross sections, without sacrificing the microscopic foundation. This approach provides a practical pathway for incorporating missing medium and higher-order effects into optical model analyses relevant for nuclear structure and reaction studies.

Subensemble Acceptance Method 3.0: General Corrections to Cumulants from Exact Conservation Constraints

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.01783v1 Announce Type: cross Abstract: We present the subensemble acceptance method 3.0 (SAM-3.0), which corrects cumulants of an observable measured in a subsystem of a large system for the effect of exact global conservation of multiple charges. The required input is the set of joint grand-canonical cumulants of the acceptance observable with the total event charges, from which the canonical cumulants follow algebraically via a closed recursion based on (multivariate) partial exponential Bell polynomials. The framework accommodates any number of observables, including non-conserved quantities such as net protons, and any number of simultaneously conserved charges, including the total energy, which yields the microcanonical ensemble. The mapping contains SAM-1.0 and SAM-2.0 as special cases and, unlike SAM-2.0, reproduces the exact binomial-acceptance limit. We also derive the leading finite-size corrections from the saddle-point expansion. We apply the method to update the hydrodynamics-based non-critical baseline (Hydro-EV) for net-proton cumulants at RHIC-BES energies, finding a refined baseline that agrees with direct canonical Monte Carlo sampling and stays close to the earlier SAM-2.0 result. We further validate the formalism against direct Monte Carlo sampling with exact simultaneous conservation of baryon number, electric charge, and strangeness, including hadronic-afterburner effects.

Polarized Nucleon as a Topological Dipole

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.03123v1 Announce Type: cross Abstract: We show that a polarized nucleon generically carries a dipole distribution of topological charge density. This topological dipole follows robustly from the definition of the topological form factor and the pseudoscalar nature of the topological charge density. The strength of the topological dipole is fixed, in the chiral limit, by the flavor-singlet axial charge. We demonstrate the mechanism in a two-flavor chiral soliton model with vector mesons and the $U(1)_A$ anomaly, where the rotation of the soliton induces a singlet pseudoscalar profile and realizes the predicted dipole pattern. We also discuss possible experimental probes through exclusive $\eta$, $\eta^\prime$ production and directed-flow-like pseudoscalar-meson asymmetries correlated with magnetic fields or vorticity in relativistic heavy-ion collisions.

ML and AI for density functional theory: different priorities for Kohn-Sham and orbital-free DFT, for electronic and nuclear DFT

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.04095v1 Announce Type: cross Abstract: We overview similarities and, importantly, differences in computational bottlenecks and accuracy requirements that can be addressed with machine learning (ML) and artificial intelligence (AI) techniques in electronic and nuclear DFT. From these follow different promising methodological and algorithmic choices depending on whether one machine learns the exchange correlation (XC) functional, the kinetic energy functional (KEF), the density or the basis functions. In particular, while the popular deep neural networks remain a potent choice in the context of KS DFT, we highlight their disadvantages when building KEFs and highlight conceptual advantages - yet to be fully realized - of symbolic regression for both electronic and nuclear DFT. We point out promising approaches that can be carried from the more extensively investigated ML-enhanced electronic DFT to nuclear DFT.

Exclusive Quark and Gluon Dijet Production as Probes of GPDs at Collider Energies

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.04482v1 Announce Type: cross Abstract: We study exclusive electroproduction of dijets in the collinear factorization framework as a probe of generalized parton distributions (GPDs). For quark dijet production, we extend previous analyses by including contributions from helicity GPDs and by assessing an additional leading-order electromagnetic channel governed by elastic nucleon form factors. Furthermore, we investigate exclusive gluon dijet production. We compare our prediction to HERA data and provide projections for measurements at the future Electron-Ion Collider.

Structure of Anisotropic Magnetized Neutron Stars in f(R,T) Gravity with Realistic Equation of State

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.05333v1 Announce Type: cross Abstract: In this study, within the framework of f(R,T) modified gravity, we investigate the influence of coupling parameter, magnetic field and anisotropy parameter on the neutron star structure. This work employs an accurate equation of state (EoS), derived from realistic microscopic calculations based on the AV18 nucleon-nucleon potential, to compute the structure of this compact object. Here, determination of Schwarzschild radius, compactness, gravitational surface redshift and Kretschmann scalar within the f(R, T) gravity, confirms that our theoretical results are consistent with the observational constraints. While established physical EoSs within the framework of Einstein gravity have successfully characterized a broad range of compact objects, they remain inadequate in explaining certain massive objects residing within the mass gap (2.5 to 5 Msun). We show that some compact objects residing in the mass gap interpreted as candidates of neutron stars within the framework of f(R, T) gravity. Finally, we compare our results with the observational data from LIGO/Virgo/KAGRA and NICER, setting the parameters of the f(R, T) theory and anisotropy to successfully reproduce the masses and radii of the GW170817, PSR J0952-0607 and PSR J0740+6620 and the masses of the secondary components of GW190814 and GW200210-092254.

Compact star and compact star matter properties from a baryonic extended linear sigma model with explicit chiral symmetry breaking

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2512.23477v2 Announce Type: replace Abstract: Based on a baryonic extended linear sigma model including explicit chiral symmetry breaking effect, the structure of neutron stars with the emergence of hyperons is investigated using the relativistic mean field approximation. It is found that, except for the lightest scalar meson $\sigma$ whose structure is not well understood so far, the vacuum mass spectra of relevant hadrons and nuclear matter properties around saturation density can be well reproduced. Nevertheless, based on the present model and the applied relativistic mean field approach, we found that, to have a realistic mass-radius relation of neutron stars, the $\pi N$ sigma term $\sigma_{\pi N}$ that denotes the contribution of explicit symmetry breaking should deviate from its empirical values at vacuum. Specifically, $\sigma_{\pi N}\sim -600$ MeV, rather than $(32\text{--}89) \rm \ MeV$ at vacuum. With an appropriate choice of $\sigma_{\pi N}$ and $K(n_0)$, our framework can give a more observationally favored mass-radius relation of neutron stars with the emergence of hyperons, suggesting a possible density dependence of the low energy constants, at least within the present leading order framework with the relativistic mean field approach. The present result provides a new perspective on the relation between microscopic explicit chiral symmetry breaking in dense matter and macroscopic structure of compact stars and calls for more systematic treatments beyond leading order relativistic mean field calculation.

Insensitivity of the Coulomb breakup of halo nuclei to spectroscopic factors

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2603.10339v2 Announce Type: replace Abstract: Exotic nuclear structures such as halos are mostly studied using reactions. In Coulomb breakup, the radioactive projectile dissociates through its interaction with a heavy target. Often, a spectroscopic factor for the core-halo structure is inferred from experimental data. In this work, we present a new calculation of the Coulomb breakup of the one-neutron halo nucleus $^{11}$Be performed with a coupled-channel effective particle-rotor model of that nucleus, which accounts for the excitation of the $^{10}$Be core. Changes in the spectroscopic factor have no effect on the cross sections when the asymptotic normalisation coefficient is fixed, hence confirming the insensitivity of Coulomb-breakup cross sections to spectroscopic factors.

Nucleon Nucleon Potential Using N$3$LO Chiral Effective Field Theory

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2606.22232v2 Announce Type: replace Abstract: A microscopic description of nucleon-nucleon (NN) and nucleon-nucleus (NA) scattering is developed using chiral effective field theory (chiEFT) at next-to-next-to-next-to-leading order N3LO. The NN interaction is taken from the EGM formulation, which incorporates spectral function regularization Lambda-tilde to control short range components of the two pion exchange force, together with a Gaussian regulator Lambda to ensure convergence of the Lippmann-Schwinger (LS) equation. The regulator parameters (Lambda, Lambda-tilde) = (450, 500), (550, 600), (600, 600) MeV. The resulting chiEFT NN t-matrix is used to construct the first order optical potential, from which Wolfenstein amplitudes and elastic differential cross sections are calculated. The theoretical amplitudes (B) and (C) for pp and pn scattering at 100 and 200 MeV show good overall agreement with experimental data, with the largest discrepancies appearing in the small real component of the spin orbit amplitude. Calculations of p + 16O and p + 40Ca elastic scattering at 100 and 200 MeV reproduce the measured angular distributions with high accuracy, particularly at forward and intermediate angles. These results demonstrate that the EGM chiEFT potential provides a consistent and quantitatively reliable framework for describing NN observables and NA elastic scattering in the 100-200 MeV energy range, while highlighting the need for improved treatment of short range and spin dependent contributions at higher energies.

Macroscopic approaches to rotating neutron stars

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2508.10717v3 Announce Type: replace-cross Abstract: The macroscopic model for a neutron star (NS) as a perfect liquid drop at equilibrium is extended to rotating systems with a small frequency $\omega $ within the effective-surface (ES) approach. The gradient surface terms of the NS energy density $\cal{E}(\rho)$ in the Equation of State are taken into account along with the volume components at the leading order over the leptodermic parameter $a/R << 1$, where $a$ is the ES crust thickness and $R$ is the mean NS radius. The macroscopic NS angular momentum at small frequencies $\omega$ is used for calculations of the adiabatic moment of inertia (MI) within the Kerr metric approach in the outer Boyer-Lindquist and inner Hogan coordinate forms. The NS MI, $\Theta=\tilde{\Theta}/(1-\cal{G}_{t\varphi})$, was obtained in terms of the statistically averaged MI, $\tilde{\Theta}$, and its time and azimuthal-angle correlation, $\cal{G}_{t\varphi}$, as the sums of volume and surface components. The MI $\Theta$ depends dramatically on the effective radius $R$ due to strong gravitation and surface effects. We found significant additional rotational constraints on the radius $R$ due to the correlation term $\cal{G}_{t\varphi}$ and surface contributions. With these contributions, the adiabaticity condition is better fulfilled for a stronger gravitation in many well-known neutron stars.

Heavy quark polarization anisotropy as a novel probe of fireball geometry

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2601.22882v2 Announce Type: replace-cross Abstract: We propose a new approach to probe the initial fireball geometry in relativistic heavy-ion collisions using spin polarization. Specifically, we introduce polarization harmonics of open heavy hadrons as a novel observable sensitive to geometric anisotropies. Heavy quarks are produced in early hard scatterings and can acquire spin polarization from the strong, transient electromagnetic fields present at early times. As they propagate through the anisotropic quark-gluon plasma, medium-induced interactions lead to path-length dependent depolarization, imprinting an azimuthally anisotropic polarization pattern. Within the framework of rotational Brownian motion, we show that the resulting polarization harmonics are directly related to the initial spatial eccentricities, thereby establishing heavy-flavor polarization anisotropies as a sensitive and complementary probe of the early-time collision geometry. We present quantitative estimates of the second (elliptic) polarization harmonic associated with the recently observed $D^{*+}$ spin alignment reported by the ALICE Collaboration.

Reference Energies for Non-Relativistic Core Ionization Potentials

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2604.05920v3 Announce Type: replace-cross Abstract: Deep-lying core electrons carry highly localized, site-specific information that forms the basis of X-ray photoelectron spectroscopy. Accurately predicting their associated core ionization potentials (IPs) is a demanding theoretical task, requiring a balanced treatment of strong orbital relaxation, electron correlation, and relativistic effects. Over the years, a variety of approaches have been developed, ranging from state-specific wave function methods to linear-response formalisms and Green's function techniques. However, their assessment has often relied on comparisons with experiment, where multiple sources of error (basis set incompleteness, relativistic corrections, and vibrational effects) are entangled, making it difficult to isolate the performance of correlation treatments. In the present work, we establish a consistent, theory-based benchmark for core IPs by computing 84 non-relativistic values (73 second-row and 11 third-row IPs) at the full configuration interaction level within the core-valence separation approximation, using large correlation-consistent basis sets augmented with tight-core and diffuse functions (aug-cc-pCVXZ). These results define theoretical best estimates within a fixed finite basis set, providing a chemically accurate reference for method development and validation. Importantly, our dataset allows for systematic, theory-versus-theory comparisons that disentangle correlation and relaxation effects from other physical contributions. On this basis, we assess the performance of widely used approximate methods, including equation-of-motion coupled-cluster approaches up to the inclusion of quadruple excitations, the one-shot $G_0W_0$ scheme, as well as state-specific methods.

Possible Evidence for Neutral Color-Singlet $q\bar q$ Quark Matter from High-Energy Pb-Emulsion Collisions

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2604.23473v2 Announce Type: replace-cross Abstract: The invariant mass spectrum of $e^+e^-$ pairs produced in high-energy Pb-emulsion collisions at 160 A GeV at CERN SPS exhibits a highly complex structure of a broad enhancement at 11$\pm$1 MeV with a full width of about 10 MeV, and additional many narrow resonances within the experimental bin width of 2 MeV, including a prominent narrow resonance at 19 $\pm$1 MeV that provides an independent support for the hypothetical X17 particle. We show that the highly complex spectrum may be coherently described as the signatures for the neutral color-singlet $q\bar q$ quark matter in both its deconfined phase as well as its confined phase. That is, the broad enhancement at 11$\pm$1 MeV may arise from thermal annihilation of QED(U(1))-deconfined quarks and antiquarks into $e^+e^-$ pairs at the phase transition temperature $T_c$(QED), which can be theoretically estimated to be 4.75 $\pm$ 1.04 MeV from the transitional equilibrium condition. The observed narrow resonances at 3$\pm$1 and 7$\pm$1 MeV may correspond to the QED(U(1))-deconfined $u\bar u$ and $d\bar d$ Coulomb bound states near their quark rest masses, respectively, whereas the observed narrow resonance at 19 $\pm$ 1 MeV may correspond to the QED(U(1))-confined isoscalar QED meson. The approximate agreement between the theoretical and the experimental spectrum suggests tentatively that both QED(U(1))-confined and QED(U(1))-deconfined neutral color-singlet $q\bar q$ quark matter may have been produced in these high-energy Pb-emulsion collision, pending confirmation of the Pb-emulsion collision data. We propose future experiments to confirm or refute these findings.

Soft-Radiation-Induced Decoherence of Heavy-Quark Spin Entanglement at the Electron-Ion Collider

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2606.29944v2 Announce Type: replace-cross Abstract: Using the soft-gluon theorem, we identify a soft-recoil mechanism by which unresolved gluon radiation induces decoherence in the spin correlations of heavy quark-antiquark pairs produced in deep-inelastic scattering. We show the eikonal soft contribution preserves the Born spin structure, whereas the subleading soft term generates stochastic recoil-induced rotations of the spin-correlation plane. Upon tracing over the unresolved gluon, these rotations produce an effective dephasing channel: the normal-axis correlation remains unchanged at this order, while the in-plane spin coherences are suppressed. We estimate the resulting reduction of concurrence and Bell-CHSH violation, and propose a radiation-binned EIC observable based on the ratio of in-plane to normal spin correlations. This observable isolates the characteristic anisotropic suppression predicted by the soft-recoil mechanism and provides a measurable handle on radiation-induced spin decoherence of an entangled quark-antiquark pair produced in a deep-inelastic scattering process.

Numerical Computation of Quasiperiodic Reducible Saddle-Node Bifurcations: a Parameterization Method Approach

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.03498v1 Announce Type: cross Abstract: We present a method for computing reducible, normally hyperbolic, invariant tori with internal quasiperiodic dynamics in autonomous ordinary differential equation systems. The approach is based on the parameterization method of KAM theory; thus, it is a Newton scheme with small divisors. Since the inner dynamics of the torus is prescribed, the corresponding system parameters for which such a torus exists are simultaneously determined. The method is amenable to a form of pseudo-arclength continuation, enabling the traversal and computation of saddle-node bifurcations. We give explicit algorithms for the methods and demonstrate their applicability with two numerical examples.

Operator-theoretic approach to the partial integration of randomly coupled phase oscillators

Tue, 07 Jul 2026 00:00:00 -0400

arXiv:2607.02617v1 Announce Type: cross Abstract: In our previous work [arXiv:2504.06248], we adopted Koopman theory to link the existence of different constants of motion to the presence of specific network motifs of Kuramoto oscillators. Yet, it remains to be shown how the partial integration can be carried out using the Koopman generator and its eigenfunctions. In this paper, we construct a random graph from network motifs that admit Koopman eigenfunctions and conserved quantities, and use it to define a partially integrable Kuramoto model. We perform the partial integration of the introduced model when there are monomial eigenfunctions and conserved cross-ratios, while providing an operator-theoretic derivation of the Watanabe-Strogatz transformation based on Magnus expansion and a recent result on closed forms of the Baker-Campbell-Hausdorff formula [arXiv:1502.06589].

Electronic Bursting Neuron: design, equations and hardware implementation

Fri, 03 Jul 2026 00:00:00 -0400

arXiv:2607.02122v1 Announce Type: cross Abstract: Electronic neurons are a keystone for construction of the spiking neural networks which have numerous applications in neuroprosthetics, artificial memory, intensive calculations etc. A number of concepts of electronic neurons has been already proposedm with some of them implemented in hardware. However, new schemes are of significant interest since the existing ones do not fit all requirements: either they are too complex and expensive in realization, or they are not able to demonstrate all demanded regimes, or their do not have a appropriate mathematical description and therefore may be investigated only experimentally etc. In this study we propose a new design of bursting electronic neuron constructed as a circuit implementation of the equations of a phase-locked loop system. To succeed, we use a novel hybrid approach: we start from the phenomenological equations providing the demanded, then we adjust and modify these equations to simplify the implementation rather than implementing the biophysical equations into thee hardware directly or writing equations for the already constructed circuit. The resulting circuit is simple in implementation and well matches the underlying equations. It can be used for description of not only a single neuron, but small neural circuits too.

The Binary Crisis Clock: Controlled by Sparse Ternary Interventions

Fri, 03 Jul 2026 00:00:00 -0400

arXiv:2607.02207v1 Announce Type: cross Abstract: We investigate modular Laplacian automata on triangular lattices with evolution governed by binary and ternary moduli. Extending previous studies on square lattices, we examine how lattice geometry influences long-term growth, density, fragmentation, and the emergence of self-similar structures. We further investigate whether sparse ternary interventions can stabilize predominantly binary dynamics. The experiments reveal that mask geometry is the primary determinant of large-scale morphology. Full hexagonal masks generate recurrent density crises and fragmentation, whereas triangular masks support persistent growth and reveal a threshold phenomenon governed by growth-capable nuclei. Although seed symmetry influences transient behaviour, the asymptotic morphology is inherited mainly from the mask. To control binary fragmentation, we investigate sparse developmental ternary perturbations in which a small number of carefully timed occurrences of modulus 3 are inserted into an otherwise binary sequence. A Monte Carlo optimization demonstrates that as few as three interventions are sufficient to redirect the subsequent binary evolution toward substantially denser carpet-like configurations. The effectiveness of this strategy depends primarily on the timing of the interventions rather than on their number. Analysis of the post-intervention dynamics shows that ternary shaping does not replace binary evolution. Instead, it produces denser self-similar structures, substantially reduces crisis depth, and resets the phase of the binary crisis clock. The results suggest that geometry determines the family of admissible morphologies, whereas sparse developmental perturbations select favourable long-term trajectories within that family.

Learning Effective Soliton Dynamics from Scattering Data

Fri, 03 Jul 2026 00:00:00 -0400

arXiv:2607.01545v1 Announce Type: cross Abstract: The inverse scattering transform (IST) provides the standard theoretical framework for deriving soliton dynamics. Traditionally, such derivations have been of an analytical, rather than data-driven, nature. In this paper, we combine the conceptual framework of the IST with weak-form system identification methods to discover effective soliton dynamics directly from observed scattering data, without assuming prior knowledge of the scattering equations. Our method avoids parameterizing solitary waves via ad hoc curve-fitting by working in the scattering domain, yielding interpretable low-dimensional models that remain valid in perturbed and near-integrable regimes. We demonstrate the performance of the proposed approach on synthetic and experimental data governed by shallow-water equations of Korteweg--de Vries-type and recover models that are consistent with canonical IST theory.

Gamma-ray production cross sections in proton interactions with natMg, natSi and 56Fe targets: measurement over the energy range of $E_p = 66$-125 MeV, data analysis, results and discussion. Astrophysical implications

Fri, 03 Jul 2026 00:00:00 -0400

arXiv:2607.02202v1 Announce Type: new Abstract: We have measured nuclear gamma-ray line production cross sections in interactions of highly accelerated proton beams with various target nuclei abundant in astrophysical sites. The experiments were carried out at the 200-MV Separated Sector Cyclotron (SSC) of iThemba LABS (near Cape Town, in South Africa) using a high-energy resolution and high efficiency detection system for registering the emitted gamma-ray photons. We report and discuss in this paper the collected experimental data sets for various gamma-ray lines produced in bombarding natMg, natSi and 56Fe targets with proton beams of incident energies of Ep = 66, 80, 95, 110 and 125 MeV. After describing the experimental set up and the data analysis method used, we report and discuss our total experimental cross section results in comparisons to previous counterparts from the literature, to a semi-empirical compilation and to the predictions of nuclear reaction theory via performed TALYS code calculations. Significantly improved agreements between theory and experiment are point out when using our modified optical model potential and B\^eta (lambda) level deformation parameters instead of the default input parameters built in TALYS. Finally, we put into perspective the applications of our results in nuclear physics and astrophysics with drawing relevant conclusions. gammaKeywords: Proton-induced nuclear reactions; gamma-ray production cross sections; gamma-ray spectrometry; gamma-ray spectroscopy; Astrophysical implications

Nuclear shell evolution near N = 6, 14, 20 and 28: insights from nuclear charge radii of short-lived nuclei derived from binding energies

Fri, 03 Jul 2026 00:00:00 -0400

arXiv:2607.01298v1 Announce Type: cross Abstract: A deep understanding of the evolution of nuclear shell structure correlating with the nucleon number is crucial for unraveling the fundamental properties of the nuclear structure and for exploring new nuclear physics phenomena far from the $\beta$-stability line. Although significant progress has been made in probing nuclear shell evolution via the measurements of nuclear root-mean-square charge radii, $R_{\text{ch}}$, the scarcity of new data for short-lived and exotic nuclei due to the increasing difficulty of measurements presents a formidable challenge in obtaining deeper and more universal insights into the nature of shell evolution. To mitigate this issue, we develop an improved method, accounting for the exchange term, charge-symmetry breaking effect, and odd-even staggering effect in the Coulomb energy formulation compared with that proposed by Liu et al. [Phys. Lett. B 872, 140046 (2026)], to determine unmeasured $R_{\text{ch}}$ values. Using the improved method, the $R_{\text{ch}}$ values of 59 nuclei are determined from their measured binding energies ($B$) and the respective $B$ and $R_{\text{ch}}$ of their mirror partners. We then systematically study the shell evolution near $N=6$, 14, 20 and 28 (sub)shells by placing the newly obtained $R_{\text{ch}}$ values into the corresponding isotopic chains. More comprehensive insights into the properties of nuclear shell evolution, particularly for the neutron-deficient sectors of the studied shell regions, e.g., $p$, $sd$ and $pf$ shells, are acquired, advancing our understanding of nuclear shell evolution in the light and intermediate mass region.

Determining the dynamic deformation of $^{140}$Ce by constraining coupled-channels parameters for fusion

Fri, 03 Jul 2026 00:00:00 -0400

arXiv:2607.01309v1 Announce Type: cross Abstract: We present a systematic study of the dynamic deformation of 140Ce using 16O and 36S projectiles in heavy-ion fusion reactions, combining experimental data, a Gaussian analytic-barrier framework and coupled-channels calculations. Fusion cross sections for 16O+140Ce are measured from ~17% above to ~12.4% below the Bass barrier. Fusion data for 36S+140Ce are obtained from the literature. Deformation parameters of 140Ce are extracted via chi-square minimization and Bayesian analysis, with independent Bayesian Model Averaging yielding beta_2 = 0.09 +/- 0.03 and beta_3 = 0.18 +/- 0.02, consistent across both systems. The extracted parameters are tested in the 28Si+140Ce system, where coupled-channels calculations including transfer of a pair of neutrons (2n) reproduce both the fusion excitation function and the barrier distribution. The positive Q-value 2n-pickup channel enhances fusion in this reaction, while the projectile's vibrational or rotational nature results in similar structure of the barrier distribution. This study demonstrates that the Gaussian analytic recipe is quite effective in deriving the fusion barrier distribution which proves to be a sensitive probe of intrinsic nuclear deformation. Further, coupled-channels analysis across multiple systems ensures robustness of the extracted deformation parameters.

Evidence of the Excited X(5)-like Critical-Point Symmetry Structures in 152Sm

Fri, 03 Jul 2026 00:00:00 -0400

arXiv:2606.21269v2 Announce Type: replace Abstract: The positive-parity structure of 152Sm has been investigated through high-statistics {\gamma}-ray spectroscopy following the (150Nd({\alpha},2n)152Sm reaction at Elab = 26 MeV. Several collective structures built on excited 0+ states have been extended through the observation of new levels and {\gamma}-ray transitions, and spin-parity assignments have been established using directional-correlation and linear-polarization measurements. Electromagnetic transition strengths (B(E2)), deduced from measured branching ratios and known level lifetimes, reveal pronounced collectivity among the excited configurations. The resulting level scheme provides evidence for a sequence of excited collective bands extending beyond the well-known ground-state and first excited 0+ structures. The excitation energies and transition strengths are examined within the framework of the X(5) critical-point description of the first-order U(5)-SU(3) shape-phase transition. In addition to the established X(5)-like features of the low-lying spectrum, the observed systematics of the higher-lying bands are found to be consistent with excited collective structures exhibiting X(5)-like characteristics. The results provide new constraints on the realization of critical-point behavior in finite nuclei and on the evolution of collectivity in the N=90 region.

r-Process Nucleosynthesis With Ab Initio Nuclear Masses Around The N=82 Shell Closure

Fri, 03 Jul 2026 00:00:00 -0400

arXiv:2509.19131v2 Announce Type: replace-cross Abstract: Our understanding of the origin of heavy elements beyond iron relies on the rapid neutron capture process (r-process), which accounts for roughly half of their cosmic abundance. However, the extreme neutron-rich conditions required for the r-process involve many nuclei that remain experimentally inaccessible, making theoretical predictions essential. We explore the impact of nuclear masses calculated with the ab initio valence-space in-medium similarity renormalization group, focusing on the region around the N = 82 shell closure. We show for the first time that such ab initio mass calculations can be used to refine r-process predictions compared to global, but more phenomenological mass models. With the ab initio masses, the waiting point of the second r-process peak is strengthened, which leads to an overall slower nucleosynthesis flow, lower abundances of nuclei beyond the peak, and a stronger shift of the third r-process peak.

Fundamental impossibility of a superradiant neutrino laser

Fri, 03 Jul 2026 00:00:00 -0400

arXiv:2510.21705v2 Announce Type: replace-cross Abstract: Here we address the fundamental question of whether an idealized system of $N$ atoms will show collective behavior and superradiance when it emits fermions instead of photons. We show that for single-fermion emission processes, the maximum emission is $\propto N$ and not $\propto N^2$, which proves the absence of superradiance and shows that the recent proposal to realize a superradiant neutrino laser is impossible. This can be understood as either destructive interference of fermionic transition amplitudes, or Pauli blockade by collective excitations with fermionic nature. We derive the exact solution of the fermionic Dicke problem and analyze the decay dynamics in various regimes. We extend the proof to arbitrary Hamiltonians and show that the jump rate operator for neutrino emission has a maximum eigenvalue of $N$ times the single-particle rate $\Gamma_0$. States with low excitation can show collective behavior and emit at a rate of $N \Gamma_0$.

Cryogenic source of atomic tritium for neutrino-mass measurements and precision spectroscopy

Fri, 03 Jul 2026 00:00:00 -0400

arXiv:2511.08313v3 Announce Type: replace-cross Abstract: We propose a concept for a cryogenic source of atomic tritium at sub-Kelvin temperatures and energies suitable for magnetic trapping. The source is based on the dissociation of solid molecular T2 films below 1 K by electrons from a pulsed RF discharge, a technique recently demonstrated for atomic hydrogen, combined with buffer-gas cooling and magnetic confinement. We analyze the key processes limiting the source performance, adsorption, spin exchange and recombination, and show that atomic tritium fluxes exceeding 1e15 1/s at kinetic energies of 100 mK can be achieved at the entrance to the magnetic trap. Such a source would enable Doppler-free two-photon 1S-2S spectroscopy in atomic tritium for high-precision measurements of the triton charge radius, providing a crucial benchmark for bound-state QED and improving the comparison between electronic, muonic, and scattering determinations of nuclear sizes in light systems. Beyond spectroscopy, an atomic tritium source avoids molecular final state broadening in the beta decay and is therefore necessary for next generation neutrino mass measurements; combined with detector technologies such as sub-eV resolution quantum sensors or cyclotron radiation emission spectroscopy, it enables an order of magnitude improvement compared to the current best experimental limit. Additionally, the source can be used to generate a beam of low field seeking deuterium atoms for loading magnetic traps, an important benchmark before trapping tritium atoms, which is useful for precision spectroscopy.

Gr\"unwald--Letnikov Memory Truncation in a Fractional Duffing Oscillator: Coherence Loss and Effective Delay Complexity

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2605.03587v3 Announce Type: replace Abstract: We investigate the dynamical and analytical consequences of truncating the Gr\"unwald--Letnikov memory term in a fractional Duffing oscillator. The truncated memory is treated not merely as a computational approximation, but as a finite-memory modification of the underlying dynamical system. We define a coherence-loss time from direct comparisons between the full-history discrete GL reference and its truncated-memory counterpart, and use it to extract critical memory horizons in parameter planes involving the forcing amplitude and the fractional order. The results reveal strongly non-monotonic critical memory horizons, showing that the retained memory required to preserve coherence depends on the forcing regime, the fractional order, and the nonlinear sensitivity of the dynamics. We also derive a local characteristic equation for the truncated GL kernel and show that it admits a local delay-type interpretation. In particular, a low-order matching yields an effective representation in terms of an instantaneous contribution plus a delayed exponential term, providing a causal local surrogate of the finite-memory kernel. This local spectral viewpoint motivates a positive-delay exponential representation of the truncated kernel. The minimum number of positive-delay modes required to reach a prescribed spectral accuracy defines an operational delay-complexity measure, $r_{\min}$. Overall, the truncated GL kernel emerges as an intermediate object between distributed fractional memory and delay-type dynamics, with a local spectral structure that is associated with the observed coherence loss and provides an operational diagnostic of effective delay complexity.

Nuclear electromagnetic moments by spin-precession methods

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2607.00900v1 Announce Type: new Abstract: Nuclear moment studies carried out with spin-precession methods at and after the turn of the millennium are critically assessed. A period of about 30 years is covered, during which much of} the focus of nuclear structure research shifted from high-spin physics to studies of neutron-rich exotic nuclei. The formalism for the extraction of nuclear moments is described. The $\beta$-nuclear magnetic resonance/nuclear quadrupole resonance ($\beta$-NMR/NQR), the time-dependent perturbed angular distribution (TDPAD), the transient field, the recoil-in-vacuum (RIV), and the tilted-foils methods for measurements of nuclear magnetic dipole and electric quadrupole moments are described in detail, as well as the requirements for their application in studies of exotic nuclei. The impact of nuclear-moment measurements on the understanding of key topics of nuclear structure research is discussed. {Key results on short-lived states, mainly from transient-field measurements, are reviewed. Included are comparisons with large-basis shell model calculations, discussions on the nature of weakly-collective nuclei, insights into emerging collectivity away from closed shells, and electromagnetic properties of odd-$A$ rotors.} In the field of high-spin physics, research related to high-spin yrast and $\mathrm{K}$ isomers, superdeformation, magnetic, anti-magnetic, and chiral rotation is covered. In neutron-rich exotic nuclei, studies related to the $\mathrm{N=20}$, $\mathrm{N=28}$ and $\mathrm{N=40}$ ``islands of inversion'', the structure of nuclei around $^{68-78}$Ni and $^{132}$Sn, and in the $A \sim 100$ mass region are discussed.

In Memoriam: Igal Talmi (1925-2026)

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2607.00787v1 Announce Type: cross Abstract: A brief obituary of Igal Talmi (1925-2026) focusing on his scientific heritage. Published in Nuclear Physics News 36 (2026) 39-40.

First Kaonic Boron Isotopes Measurements with SIDDHARTA-2 at DA$\Phi$NE

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2605.26979v2 Announce Type: replace Abstract: A precision measurement of X-ray transitions in kaonic boron, performed by the SIDDHARTA-2 collaboration at the DA$\Phi$NE collider, is reported. The energies and yields of the $5g\rightarrow4f$ and $4f\rightarrow3d$ transitions were determined for both boron isotopes, kaonic ${}^{10}$B and kaonic ${}^{11}$B. For the $5g\rightarrow4f$ transition, the measured energies are $7064.62 \pm 16.93~(\mathrm{stat.}) \pm 2.00~(\mathrm{sys.})$~eV for kaonic ${}^{11}$B and $6920.96 \pm 58.23~(\mathrm{stat.}) \pm 2.00~(\mathrm{sys.})$~eV for kaonic ${}^{10}$B. For the $4f\rightarrow3d$ transition, the corresponding values are $15293.33 \pm 4.80~(\mathrm{stat.}) \pm 5.30~(\mathrm{sys.})$~eV and $15180.11 \pm 20.86~(\mathrm{stat.}) \pm 5.30~(\mathrm{sys.})$~eV, respectively. The yields for the $5g\rightarrow4f$ transition are $0.076 \pm 0.013~(\mathrm{stat.})^{+0.012}_{-0.011}~(\mathrm{sys.})$ for kaonic ${}^{11}$B and $0.079 \pm 0.014~(\mathrm{stat.})~^{+0.013}_{-0.011}~(\mathrm{sys.})$ for kaonic ${}^{10}$B. For the $4f\rightarrow3d$ transition, the corresponding yields are $0.115 \pm 0.006~(\mathrm{stat.})~^{+0.002}_{-0.005}~(\mathrm{sys.})$ and $0.107\pm 0.007~(\mathrm{stat.})~^{+0.002}_{-0.005}~(\mathrm{sys.})$, respectively. No statistically significant deviation from pure electromagnetic (QED) calculations was observed in the measurement of the $4f\rightarrow3d$ X-ray transition in kaonic ${}^{11}$B. Interpreted as upper limits, these results impose stringent constraints on the strong-interaction energy shift and width of the 3d level in light nuclei. Translating these limits into bounds on phenomenological kaon-nucleus optical potentials, and, within specific theoretical models, on the complex scattering amplitude, we constrain and disfavor scenarios predicting large shifts or widths in boron.

Astrophysical S-factor Calculation for p-p Fusion Reaction

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2607.00487v1 Announce Type: new Abstract: The current S-factor calculations for weak pp interaction involve the determination of low-energy penetration probability using the bare Coulomb Gamow factor, which renders the nature and shape of actual interaction to be insignificant. In this work, the astrophysical S-factor is obtained utilizing the WKB action integral evaluated over the inverse scattering potential for the S-wave of pp-interaction, which does not involve bare Coulomb interaction in it. The np and pp inverse potentials are constructed using the phase function method by providing a reference potential consisting of three smoothly combined Morse functions, whose model parameters are optimized using a genetic algorithm to minimize the mean-squared error between the obtained and expected scattering phase shifts. The overlap integral between the bound-state deuteron and the scattering state of pp S-wave has been evaluated at different energies all the way up to 0.0001 MeV, and corresponding fusion cross-sections are determined. The WKB action integral has been computed at all energies without any approximations. Finally, the S-factor at various energies are calculated, and S(0) has been obtained using a supervised neural network. The value of S(0) obtained using our methodology involving complete evaluation of WKB action integral without approximations is $(0.1678\pm 0.0058)\times10^{-25}$, which is almost one order of magnitude lower than the currently accepted values using various methods. The inverse potentials constructed using the reference potential approach, which does not involve explicit consideration of nuclear $\&$ Coulomb interaction, resulting in a finite range of pp-interaction, have been successful in providing a new estimate for the astrophysical s-factor that depends on the nature and shape of the actual potentials

Long Time Energy Oscillation Between Electron Shell and Nucleus in $^{229}$Th Ions and Coherent Electron Bridge for Nuclear Quantum Battery

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2607.00607v1 Announce Type: new Abstract: The electron shell of the Thorium ion with the $M$1(8.4~eV) transition between levels and the doublet of the $^{229}$Th nucleus ground state with the similar transition represent two qubits spatially inserted one within the other. In the case of relative proximity of the energies of these transitions, weakly damped energy oscillations can be excited between qubits, namely, multiple coherent energy transfer from the electron shell to the nucleus and vice versa. This process in the $^{229}$Th ions does not require resonant (within the width of the levels) coincidence of the transition energies due to the relatively high interaction energy of the electron and nuclear currents. The electron shell ``breathes'', periodically decreasing and increasing in size. The effect can be observed in an ion trap by the intensity of light scattered by thorium-229 ions. This extends the energy range for the $^{229m}$Th$(3/2^+,8.4$~eV) isomer excitation via an electron bridge. Furthermore, the system under consideration is transformed into a nuclear quantum battery when exposed to coherent laser radiation. To ``charge'' the battery, i.e. to excite $^{229m}$Th, one can use developed methods for charging quantum batteries, in particular, coherent excitation of the electron shell followed by coherent transfer of excitation energy to the nucleus (the coherent electron bridge). This opens the way for the design of the $^{229}$Th nuclear quantum battery at the current level of technological development.

Elastic deuteron-deuteron scattering within Nuclear Lattice Effective Field Theory

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2607.00681v1 Announce Type: new Abstract: We calculate low-energy deuteron-deuteron scattering in the spin-quintet $^{5}S_2$ channel using nuclear lattice effective field theory. The calculation combines chiral interactions at next-to-next-to-next-to-leading order, implemented through wavefunction matching, with the adiabatic projection method. Because the radial cluster basis develops small norm-matrix eigenvalues at large Euclidean projection time, we investigate two stabilization procedures: Tikhonov regularization and projection onto well-resolved norm eigenmodes. The two procedures yield consistent Coulomb-subtracted phase shifts within their statistical and numerical uncertainties. A Coulomb-modified effective-range analysis gives ${}^5a_{dd} = (12.96 \pm 0.26)\,\mathrm{fm}$ and ${}^5r_{dd} = (3.62 \pm 0.79)\,\mathrm{fm}$. The phase shifts are more negative, and the scattering length is substantially larger than in previous calculations, corresponding to a stronger effective repulsion in the $^{5}S_2$ channel. These results provide a first nuclear-lattice benchmark for deuteron-deuteron scattering and establish a basis for future coupled-channel calculations of the deuteron-induced reactions relevant to big-bang nucleosynthesis.

Dipolar flow of identified hadrons at mid-rapidity using transport models

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2607.00703v1 Announce Type: new Abstract: We report a transport model study of the rapidity even component of dipolar flow, $v_{1}^{\mathrm{even}}$, for identified charged hadrons at mid-rapidity in Au+Au collisions at $\sqrt{s_{NN}} = 27-200$ GeV. The analysis is performed using the AMPT model, with comparisons to HIJING to quantify non-flow contributions. The $v_{1}^{\mathrm{even}}$ of identified hadrons ($\pi$, $K$, and $p$) shows no significant difference between particles and anti-particles at $\sqrt{s_{NN}} = 200$ GeV. However, a clear splitting between proton and anti-proton $v_{1}^{\mathrm{even}}$ develops with decreasing beam energy, while no corresponding difference is observed for mesons ($\pi^{\pm}$ and $K^{\pm}$). A comparison of the AMPT string melting and default configurations shows that the splitting arises only in the string melting scenario, where partonic interactions and quark coalescence play a dominant role. These results indicate that the proton-antiproton difference in $v_{1}^{\mathrm{even}}$ is sensitive to baryon transport and early-stage partonic dynamics. Our study highlights the potential of identified-particle $v_{1}^{\mathrm{even}}$ measurements at RHIC Beam Energy Scan energies as a novel probe of baryon stopping and the evolution of the partonic medium.

Purifying one-neutron removal as a probe of single-particle strength

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2607.01078v1 Announce Type: new Abstract: One-neutron removal reactions exhibit a strong proton-neutron asymmetry dependence in the inclusive reduction factor $R_s$, a long-standing issue that has been discussed in terms of both possible intrinsic isospin dependence of single-particle strength and reaction-mechanism effects. We address this issue by reframing inclusive removal as a coupled fast-dynamics and deexcitation process, and by validating this transport-deexcitation chain against a global, mutually constraining data set. Confronting 73 one-neutron removal cross sections and 28 residue parallel-momentum distributions with isospin-dependent quantum molecular dynamics followed by GEMINI evaporation shows that the apparent $R_s$-$\Delta S$ trend is correlated with evaporation feeding and evaporation loss. By subtracting the feeding contribution and correcting for the loss component in the measured cross sections, we construct a purified reduction factor $R_{\rm dir}$, that more closely reflects single-particle strength than the inclusive $R_s$. The resulting $R_{\rm dir}$ exhibits a much weaker $\Delta S$ dependence within current uncertainties, consistent with the weak isospin-asymmetry dependence observed in nucleon-transfer and quasifree-knockout systematics.

Semi-regularised three-body pseudopotential for mean-field and beyond-mean-field calculations

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2607.01190v1 Announce Type: new Abstract: We derive the most general form of a local leading-order semi-regularised three-body pseudopotential. This particular form of pseudopotential is developed with the aim of generating contributions to the nuclear energy density functional (EDF) in both the particle-hole and particle-particle channels and, hence, to be usable in mean-field and beyond-mean-field calculations without ambiguities or mathematical difficulties. Once the EDF is obtained, analytical expressions of commonly considered properties of infinite nuclear matter are provided. Finally, the structure of the EDF and the associated mean fields are given for spherically-symmetric systems.

$\rho$ mesons in finite magnetic field and finite temperature

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2605.00561v3 Announce Type: replace Abstract: The mass spectra of $\rho$ mesons ($\rho_{Q=\pm 1}^{s_z=0,\pm 1}$ and $\rho_{Q=0}^{s_z=0,\pm 1}$) at finite magnetic field and temperature are studied in frame of the two-flavor Nambu-Jona-Lasinio model. Fully considering the breaking of translational invariance induced by external magnetic field, the analytical form of $\rho$ meson propagators have been derived in the Ritus scheme and Schwinger scheme, which gives the same algebraic formula. When solving the pole equation of $\rho$ meson propagators, multiple solutions of the meson mass appear due to the dimension reduction of their constituent quarks in magnetic fields. At vanishing temperature, we focus on the $\rho$ meson masses $M_{\rho}$ corresponding to the lowest value solution of the pole equation. $M_{\rho^{-}_+}$, $M_{\rho^{0}_+}$ and $M_{\rho^{\pm}_0}$ increase with magnetic field. $M_{\rho^{+}_+}$ firstly decreases and then becomes saturated with increasing magnetic field. $M_{\rho^0_0}$ is not sensitive to magnetic field. These results are consistent with the available LQCD simulations. At finite temperature, we discuss the lowest four/five solutions of $\rho$ meson masses $M^{i=0,1,2,3,4}_{\rho}$. With fixed magnetic field, they decrease with temperature, and approach the mass sum of their constituent quarks at high temperature. The mass solution $M^{i}_{\rho}$ for different mesons $\rho_+^{0,\pm}$ and $\rho_0^{0,\pm}$ may become degenerate at finite magnetic field and temperature.

Out-of-equilibrium contributions to charm hadrons in a fluid-dynamic approach

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2510.25601v2 Announce Type: replace-cross Abstract: Building on previous studies that demonstrated the applicability of a fluid-dynamic description of charm quarks in the quark-gluon plasma, the present work extends the framework by computing the out-of-equilibrium contributions to the distribution function of charm hadrons. The analysis includes corrections arising from the initial out-of-equilibrium distribution of charm quarks after a free-streaming phase, as well as from the freeze-out surface within fluid dynamics. These results enable the exact computation of integrated yields and transverse momentum distributions of charm hadrons for different values of the spatial diffusion coefficient, thereby providing the basis for a systematic determination of the charm transport coefficients. A preliminary comparison of our model with the available experimental data shows compatibility within uncertainties. In addition, the limits of applicability of the approach are identified by determining the transverse-momentum region in which charm hadrons are described by a well-defined, positive distribution function.

Neural Wavefunctions in Quantum Field Theory I: Asymptotic Freedom

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2606.20791v2 Announce Type: replace-cross Abstract: We present a variational approach to quantum field theory based on wavefunctions parameterized by neural networks. While variational methods have a celebrated history across many fields, their application to quantum field theory has been limited by well-known challenges. We show that neural-network wavefunctions, combined with modern machine-learning techniques, enable competitive variational calculations in nontrivial field theories. As a demonstration, we reproduce the essential features of the two-dimensional nonlinear $\sigma$-model: asymptotic freedom, dynamical mass generation and the model's step-scaling function.

Self-Organized Learning in Oscillatory Neural Networks with Memristive Signed Couplings

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2607.00286v1 Announce Type: cross Abstract: Oscillatory neural networks (ONNs) have emerged as a promising neuromorphic architecture, leveraging coupled dynamical systems to perform computation and represent information through phase relationships. Their interactions can be designed to support intrinsic energy-minimizing dynamics, enabling tasks such as associative memory and optimization, and positioning them as a candidate architecture for continuous learning and inference. We present a neuromorphic primitive implemented using memristive edges with inhibitory couplings as a potential design for autonomous learning, and provide circuit simulation validation that the system is capable of denoising noisy inputs on an auto-associative task. While numerical Hopfield/Ising models routinely assume signed weights, neuromorphic implementations of ONNs often fail to realize negative weights due to device and circuit constraints. A practically implementable route to inhibitory (negative) weights is particularly valuable: it expands the class of attractor structures accessible to oscillator networks beyond purely synchronous couplings, and supports phase-coded memories where anti-phase constraints are not merely transiently enforced during training but can persist autonomously after release. We provide circuit simulations and theoretical analyses demonstrating that signed effective weights are necessary for anti-phase attractors to persist autonomously.

When is vaccine prioritization worth optimizing?

Thu, 02 Jul 2026 00:00:00 -0400

arXiv:2607.00484v1 Announce Type: cross Abstract: Optimizing vaccine prioritization is often treated as the default policy response when vaccine supply is limited. Yet optimized prioritization carries administrative, ethical and communication costs, motivating an upstream question: whether differences among vaccine allocations can alter epidemic outcomes enough to make optimization epidemiologically necessary. We show that optimization is not always worth pursuing: in some regimes, vaccination markedly reduces epidemic burden, but many feasible allocation rules perform almost equally well, making the necessity of optimization low. We quantify this necessity as the range of epidemic outcomes generated by different allocations under fixed supply and show that it is governed by competition between vaccinating high-contact groups to slow transmission and vaccinating groups that benefit most directly: necessity is low when these protection routes are balanced and high when one dominates. Increasing transmission intensity changes this balance and drives a transition in the optimal allocation from transmission-focused prioritization toward direct protection. Different prevention objectives exhibit distinct transition thresholds, creating regimes in which optimizing one objective substantially compromises another, thereby revealing when the choice of prevention target matters most. This framework reframes vaccine prioritization as a prior decision problem, identifying when optimization is warranted, when simpler rules suffice, and when prevention goals conflict.

Fractional short-time dynamics in driven quantum gases

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2605.28606v2 Announce Type: replace-cross Abstract: Quantum gases with short-range attractive interaction tend to form pairs. For time-dependent interaction we find that the pairing amplitude at small separation satisfies a fractional differential equation (FDE). We derive analytic solutions of the pairing evolution for sudden interaction quenches and power-law drives toward resonant scattering. We observe universal short-time dynamics governed by a nonrelativistic conformal fixed point at which the momentum distribution exhibits self-similar dynamic scaling, in quantitative agreement with experiment. At longer times, many-body effects induce relaxation toward an equilibrium state. In this limit, the FDE turns into a M\"uller-Israel-Stewart type equation that describes a hydrodynamic attractor approaching equilibrium.

Landau-Zener-St\"uckelberg-Majorana dynamics of magnetized quarkonia

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2512.24072v2 Announce Type: replace-cross Abstract: The mass spectrum of hadrons in magnetic fields features avoided level-crossing structures arising from the mixing of spin eigenstates. In this work, we investigate the impact of level-crossing dynamics of charmonia subjected to time-dependent magnetic fields, where we particularly focus on the occupation probabilities of two or more states as they undergo transitions at avoided crossings. Using a static spectrum of charmonia in magnetic fields, we construct a multi-channel Landau-Zener Hamiltonian. Within this framework, we analyze the time evolution under several representative magnetic-field profiles, including linear ramps and Gaussian decays corresponding to single-passage dynamics, as well as Gaussian pulses realizing double-passage dynamics, and compute the occupation probabilities over a wide range of sweep rates and initial conditions. Our results show that nonadiabatic dynamics, including Landau-Zener transitions and St\"uckelberg interference, strongly influences the occupation probabilities of charmonia. These findings provide new insights into the real-time dynamics of magnetized hadrons and offer useful guidance for future lattice simulation studies.

Input-driven analysis in predicting nuclear charge radii using Monte Carlo dropout Bayesian neural network

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.22937v2 Announce Type: replace Abstract: Nuclei charge radii play an essential role in understanding the fundamental interactions of finite quantum fermion systems. In this work, input-driven Bayesian neural network based on the Monte Carlo dropout approach has been built to characterize the systematic evolution of charge radii of nuclei with proton number $Z\geq20$ and mass number $A\geq40$. The motivated underlying mechanisms have been introduced into the input structures, which contain pairing effect, isospin asymmetry degree, the correlations between the valence nucleons and valence holes for neutron and proton, quadrupole deformation parameter $\beta_{20}$, and the local shape staggering phenomena of $^{181,183,185}$Hg isotopes.In addition, shell quenching effect is also taken into account by incorporating the modified Casten factor $P^{*}$ into the input structure. The quadrupole deformation parameters $\beta_{20}$ derived from finite-range droplet model (FRDM), relativistic mean field (RMF) theory and Weizs\"{a}cker-Skyrme (WS) approach are employed to analyze the local variations of nuclear charge radii.The hyperparameter is adjusted automatically in the constructed model.The calibrated results give comparable root-mean-square deviations (RMSD) in the training and validation sets with various shape deformation inputs. The abrupt increase in charge radii around N=60 is well reproduced along Z=37-40 isotopic chains, but this trend is less pronounced along Z=36 and 41 chains. This provides a indicator to confirm the rapid shape-phase transition regions around N=60 from the perspective of finite nuclei size. Shell quenching effect of charge radii along the bismuth isotopes are reproduced well at N=126, but slight deviations can be encountered due to the absence of high-order octupole deformation around N=130 regions and shape-staggering phenomena toward neutron-deficient regions, respectively. This means that...

How long can an atomic nucleus remain standing ? -- a fundamental quantum question

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.03272v3 Announce Type: replace Abstract: The shape of an object is of fundamental interest and high importance, but is not a straightforward subject if the object is on quantum scale. We here discuss how a shaped micro-object can be looked at within quantum mechanics. For this purpose, atomic nuclei are suitable, because they are tiny shaped objects. The majority of atomic nuclei are shaped like ellipsoids. Although an ellipsoid is oriented in a direction classically, such a nucleus is pointing in all directions with certain probabilities in quantum eigenstates, fulfilling rotational symmetry. This makes the direct observation of shapes formidably difficult. Here, we show, including examples, that the ellipsoidal nucleus is basically standing in a fixed direction for finite time \sim some 10^{-23} sec, as a robust consequence of time-dependent Schrodinger equation in quantum mechanics and a well-known rotational feature of nuclei. This consequence not only provides Relativistic Heavy-Ion Collisions9 with experimental feasibilities, but also leads to a deeper general understanding of stationary states with restored broken symmetry: time-dependent symmetry-breaking (e.g., ellipsoid shape) properties arise from stationary states with symmetry. This work depicts direct relevance to fusion, fission and $\alpha$ decay/emission in terms of time evolution, including applications to the synthesis of superheavy elements.

Pseudo-gauge invariant non-equilibrium density operator

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2507.09249v2 Announce Type: replace Abstract: We obtain a form of the local thermodynamic equilibrium density operator which is invariant under pseudo-gauge transformations of the stress-energy and the spin tensors. This operator is an excellent candidate to describe the dynamics of a system which is assumed to achieve local equilibrium from a pseudo-gauge invariant quantum state, a situation which is believed to occur, for instance, in nuclear collisions at very high energy. As a consequence of pseudo-gauge invariance, the ambiguity affecting the predictions of mean values of observables from a local equilibrium state can be removed.

Finite-Density Dynamics of Chemically Equilibrating QGP in Conformal Gubser Flow and Hard Thermal Photon Production

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31749v1 Announce Type: cross Abstract: We study the chemical equilibration of a hot and dense quark-gluon plasma (QGP) at finite baryon density produced in relativistic heavy-ion collisions within conformal Gubser flow. Chemical non-equilibrium is incorporated through fugacity parameters in the parton phase-space distribution functions, whose evolution is governed by master rate equations coupled to the hydrodynamic expansion with transverse flow. We analyse the interplay between chemical equilibration and finite-density dynamics, and investigate its impact on hard thermal photon production. We observe that both finite density and transverse expansion delay chemical equilibration, leading to a chemically undersaturated medium with quarks lagging behind gluons. While the overall thermal photon yield from the expanding system is suppressed in the non-equilibrium scenario, we find an enhanced early-time contribution to high $p_T$ photon production. By analyzing the instantaneous photon emission in presence of chemical non-equilibrium, we demonstrate that the rates exhibit a distinct temporal structure arising from the interplay of rapid cooling and evolving fugacities. These features may provide potential observable signatures of chemical equilibration dynamics in the QGP.

Finite-range EFT for the $E1$ strength distribution of ${}^6$He

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.32037v1 Announce Type: new Abstract: Halo effective field theory (Halo EFT) is a powerful tool to describe halo nuclei and predict low-energy observables with quantified uncertainties. However, in the case that there is a leading-order interaction determined by two or more effective-range parameters, such as the $^2P_{3/2}$ $n\alpha$ interaction in $^6$He, the standard implementation in the dimer formalism leads to an energy-dependent interaction. This complicates the construction of a Hilbert space of states, especially beyond the two-body problem. As an alternative, we propose the use of a finite-range formulation of Halo EFT, which avoids these complications. For definiteness, we use separable interactions with Yamaguchi-like form factors, but other choices are possible. We solve for the ${}^6$He bound state in this finite-range EFT up to next-to-leading order (NLO) in the Halo EFT power counting and calculate the ground-state $E1$ strength distribution of $^6$He at this order. The shape of the resulting distribution agrees with that obtained in the dimer formalism of the EFT, but finite-range EFT does not require the use of a non-standard wave function normalization condition. We also calculate the root-mean-square charge radius of $^6$He and find $2.06 \pm 0.35$~fm at LO and $2.00 \pm 0.09$~fm at NLO, in agreement with experimental data. To calculate the full $E1$ strength distribution final-state interactions must be incorporated. We approximate the full-three-body scattering operator first by single M{\o}ller operators and then by products of up to three M{\o}ller operators. The resulting NLO $E1$ strength distribution agrees with the experimental data within theory uncertainties.

Nuclear excitation via inelastic scattering of low-energy vortex electrons

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31818v1 Announce Type: new Abstract: Vortex particles carrying orbital angular momenta (OAMs) have found important applications in broad fields. However, the experimental verification of OAM transfer at the nuclear scale remains a great challenge. Here, we put forward a novel method to probe such OAM transfer through nuclear excitation via inelastic scattering of low-energy vortex electrons. We develop a Dirac distorted-wave Born approximation framework that incorporates the incident-electron OAM and a nonperturbative treatment of the Coulomb field, and apply it to $^{229}\mathrm{Th}$. We find that the vortex and non-vortex electrons yield opposite angular distributions, attributed to the OAM-modified selection rule and the Coulomb-induced redistribution of partial-wave strengths, providing an angle-resolved signature. Moreover, the vortex electron exhibits topological protection in the nuclear Coulomb field. Our method offers a route to probing nuclear-scale OAM transfer and deepens our understanding of the topological properties of vortex particles.

Strong Evidence for Three-$\alpha$ Clustering in the Ground State of $^{12}\mathrm{C}$

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31437v1 Announce Type: new Abstract: The ground state of $^{12}\mathrm{C}$ has often been approximated by a mean-field picture. This conventional view has been challenged by recent nuclear theories suggesting non-negligible $\alpha$-cluster formation, but experimental evidence remains inconclusive. Here, we show that existing $^{12}\mathrm{C}(p,p\alpha)^{8}\mathrm{Be}$ data provide direct evidence for a pronounced $\alpha$ cluster formation in the ground state of $^{12}\mathrm{C}$. We analyze the data with distorted-wave impulse approximation using $\alpha$ preformation amplitudes from an unrestricted $3\alpha$ cluster model and harmonic-oscillator-based models. The results show that the former reproduces the measured cross sections, whereas the latter underestimate them by more than an order of magnitude. Thus, contrary to conventional expectations, the data support a nearly fully developed three-$\alpha$ cluster structure in the ground state of $^{12}\mathrm{C}$.

Cooling of Hybrid Stars with a 2SC+$ $ Phase

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31389v1 Announce Type: new Abstract: Recently, Fujimoto, Fukushima & Weise (2019) have proposed a new colour-superconductive state, 2SC+$ $ phase, which can be smoothly connected to the low-density baryon superfluidity in contrast to the 2SC phase. In this scenario, the neutron ${}^3P_2$ superfluidity on the low-density side of the phase transition is inherited by unpaired $d$-quarks in the 2SC phase on the high-density side. Since this could be realized in hybrid stars (neutron stars containing hadronic and quark matter), the 2SC+$ $ phase may change the properties of neutron stars compared to the traditional 2SC phase. In this work, we study the thermal evolution of hybrid stars with the 2SC+$ $ phase for the first time. We find that NSs with the 2SC+$ $ phase become hotter than those with the 2SC phase, and are close to the CFL phase. The ${}^{3}P_2$ superfluidity plays an important role in cooling curves with not the 2SC but 2SC+$ $ phases due to the suppression of quark $\beta$ decay. We therefore point out that, if the scenario of 2SC+$ $ phase is true, it could be specified through low-temperature observations such as Vela, 3C58, Vela Jr., and Vela-like pulsar.

Charged pseudoscalar mesons in a strong magnetic field under the Weinberg model

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31386v1 Announce Type: new Abstract: Recent lattice QCD simulations have further validated their earlier unusual findings: The lowest energies of charged pseudoscalar mesons $\pi^\pm$ and $K^\pm$ decrease at stronger magnetic field, though quasiparticle approximation assumes an increasing feature. We address this long-standing puzzle by employing the chiral effective Weinberg model, in which pseudoscalar and vector mesons exhibit intrinsic mutual couplings. Under this framework, charged pseudoscalar mesons deviate from pure quasiparticle behavior due to their interactions with neutral pseudoscalar and charged vector mesons. By incorporating the modifications induced by neutral pseudoscalar-charged vector loops, we demonstrate that the lowest energies of $\pi^\pm$ and $K^\pm$ indeed decrease at stronger magnetic field in both the lowest- and full-Landau-level calculations. However, instabilities emerge under a fixed mesonic coupling constant, and appear unavoidable when attempting to reproduce the observed peak structures. In contrast to the quark-antiquark meson description in models such as the NJL model, our results support the conjecture that a charged pseudoscalar meson could effectively form a molecular bound state of a neutral pseudoscalar meson and a charged vector meson in the strong magnetic field regime.

Relativistic magnetohydrodynamics from kinetic theory

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31327v1 Announce Type: new Abstract: This thesis develops a kinetic-theory framework for relativistic dissipative magnetohydrodynamics under strong electromagnetic fields, motivated by quark-gluon plasma in heavy-ion collisions. Starting from the relativistic Boltzmann-Vlasov equation and using the method of moments within the 14-moment approximation, it derives causal second-order hydrodynamic equations for relativistic plasmas with increasing generality. The work first review relativistic dissipative hydrodynamics and its kinetic foundations, emphasizing the need for Israel-Stewart-type transient theories to preserve causality and stability. Electromagnetic fields are then introduced at the microscopic level, where the Lorentz force modifies the moment hierarchy and produces anisotropic transport effects absent in field-free fluids. Next, it develops relativistic dissipative magnetohydrodynamics for a non-resistive two-component plasma of oppositely charged particles. Here, the magnetic field couples the dissipative sectors of the two species, generating relative dissipative currents and coupled shear dynamics. For Bjorken expansion, the theory predicts damped oscillations in the transverse shear sector associated with cyclotron motion. Finally, the thesis treats the resistive two-component case, where the electric field evolves dynamically and couples to charge diffusion and shear stress. The resulting theory reveals current-shear feedback, transient electromagnetic generation of momentum anisotropy, and underdamped dissipative oscillations. Applications to homogeneous and Bjorken-expanding plasmas show how resistive and electromagnetic effects modify evolution beyond standard hydrodynamics. Overall, the thesis extends relativistic dissipative hydrodynamics to magnetized and resistive plasmas, providing a microscopic foundation for future studies of strongly magnetized quark-gluon plasma and astrophysical systems.

Symmetry energy of baryon- and neutron-rich nuclear matter

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31162v1 Announce Type: new Abstract: Based on the relativistic mean-field model and assuming $G$-parity invariance, we have studied the equation of state of baryon- and neutron-rich matter produced in low-energy relativistic heavy-ion collisions. Similar to the traditional isospin symmetry energy, we define the baryon-antibaryon symmetry energy characterizing the energy difference due to the baryon-antibaryon asymmetry. The potential difference between nucleons and antinucleons is correlated with the potential contribution of the baryon-antibaryon symmetry energy mainly from the vector interaction in baryon-rich matter. The isospin symmetry energy is considerably reduced even with a small fraction of antinucleons compared to the traditional case with only nucleons. A more attractive antineutron potential than antiproton potential is observed, and the isospin splitting of the mean-field potential for antinucleons is found to be intrinsically larger than that for nucleons in baryon- and neutron-rich matter.

Correlated many-body quantum dynamics of the Peregrine soliton

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2512.16031v2 Announce Type: replace-cross Abstract: We explore the correlated dynamics underlying the formation of the quantum Peregrine soliton, a prototypical rogue-wave excitation, utilizing interaction quenches from repulsive to attractive couplings in an ultracold bosonic gas confined in a one-dimensional box trap. The latter emulates the so-called semi-classical initial conditions and the associated gradient catastrophe scenario facilitating the emergence of a high-density, doubly localized waveform. The ensuing multi-orbital variant of the Peregrine soliton features notable deviations from its mean-field sibling, including a reduced peak amplitude, wider core, absence of the side density dips, and earlier formation times. Moreover, Peregrine soliton generation yields coherence losses, while experiencing two-body bunching within each of its sides which show anti-bunching between each other. Controllable seeding of the Peregrine soliton is also demonstrated by tuning the atom number or the box length, while reducing the latter favors the generation of the time-periodic Kuznetsov-Ma breather. Our results highlight that correlations reshape the morphology of rogue-waves in the genuinely quantum, nonintegrable realm, while setting the stage for the emergent field of quantum dispersive hydrodynamics.

Real-time identification of the onset of financial rogue waves

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31475v1 Announce Type: cross Abstract: Extreme events in financial systems, often captured by indicators such as volatility, remain difficult to identify close to their onset. Volatility shares many statistical properties with other natural, complex systems which experience extreme events, which we explore in this manuscript. We extend the analogy between rogue waves in optical and hydrodynamical systems to financial volatility by identifying rogue-wave-like peaks with similar statistical properties. We use a Schr\"odinger equation where the potential follows the shape of a Kerr nonlinearity to examine the properties of financial volatility indices within a moving time window. We see evidence of Anderson localisation as a rogue peak approaches in the VIX, and show that the numerical gradient of the system's minimum eigenvalue reliably spikes at the onset of an extreme event. We adapt our methodology to simulate the real-time arrival of data, and show that all but one of the VIX's major peaks can be detected given a reasonable amount of history. We then perform two out-of-sample tests, one for the VXO index, and one for the VSTOXX index, and successfully replicate our initial results, identifying all but one major peak (87.5% or 7/8) in both cases. This method of analysis shows considerable promise as a tool for identifying potential financial crises, aiding in their mitigation.

Pattern formation in a Reaction-Diffusion Model for Amyloid-$\beta$ and Tau Interactions in Alzheimer's Disease

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.30681v1 Announce Type: cross Abstract: Alzheimer's disease (AD) is characterized by the accumulation of Amyloid-$\beta$ ($A\beta$) plaques and hyperphosphorylated Tau proteins. However, many individuals exhibit substantial $A\beta$ and Tau pathology without developing dementia, suggesting that disease progression may depend not only on pathological burden but also on the spatial organization of these proteins. Motivated by this observation, we adapt Gray-Scott reaction-diffusion model to investigate pattern formation arising from the interactions between $A\beta$ and Tau. % To systematically identify stable spatial configurations, we employ a Companion-Based Multi-Level Finite Element Method (CBMFEM) on both two-dimensional domains and anatomically realistic cortical surface meshes. Numerical simulations reveal a rich landscape of multiple steady-state solutions, which are subsequently classified into representative pattern phenotypes using principal component analysis and clustering techniques. The results demonstrate that the coupled $A\beta$--Tau system admits numerous stable spatial patterns rather than a single pathological endpoint. % These findings provide a potential mathematical framework for understanding the heterogeneity of Alzheimer's disease and the existence of cognitively resilient individuals despite significant pathological burden. More broadly, the proposed framework suggests a pattern-based therapeutic paradigm in which disease dynamics are guided toward favorable stable states rather than solely targeting the elimination of pathological proteins.

Dissipative surface solitons in two-dimensional truncated lattices with linear gain and loss

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31972v1 Announce Type: new Abstract: Dissipative solitons constitute a robust class of self-localized nonlinear states sustained by the dynamic balance between nonlinearity and gain-loss, possessing an intrinsic stability that stems from their fundamental attractor nature. When combined with lattice truncation, this balance gives rise to dissipative surface solitons (DSSs), whose existence and stability are jointly dictated by boundary-induced confinement and non-Hermitian dynamics. In two-dimensional truncated lattices with linear gain and loss, surface localization emerges within gap regimes, where families of DSSs bifurcate from linear surface localized gain modes as the nonlinearity increases. Increasing the number of waveguide rows at the interface enriches the diversity of supported surface modes in both linear and nonlinear regimes. Although multiple DSS families with distinct phase configurations may coexist within the same gap, their dynamical stability is strongly phase selective. These insights establish linear gain-loss engineering as a powerful mechanism for controlling nonlinear surface localization and provide practical guidelines for realizing robust nonlinear surface states in gain-loss-tailored photonic platforms.

Cycle holonomy captures higher-order compatibility constraints in remote synchronization

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2604.19682v2 Announce Type: replace-cross Abstract: Higher-order interactions have typically been modeled using hypergraphs or simplicial complexes, where interactions explicitly involve more than two nodes. Here we demonstrate that effective higher-order dynamical constraints emerge naturally on ordinary graphs, provided the interaction carries nontrivial topological structure. We study a gauge-coupled phase model with edge phase lags whose accumulation around closed loops produces gauge-invariant mismatches. We show that the associated twisted Laplacian admits a zero mode if and only if all cycle holonomies vanish. Consequently, global compatibility is obstructed not by local pairwise mismatches, but by intrinsic topological frustration on cycles. We then connect this framework to the symmetric Sakaguchi--Kuramoto model, whose local coupling law differs from the gauge-coupled model but whose node phases impose cycle closure on physical phase differences. For cactus graphs, path mismatches induced by the symmetric lag can be represented through associated cycle holonomies, providing a static spectral encoding of their global residual incompatibility. Our results establish a spectral framework linking frustration to cycle-level constraints and identify cycle holonomy as a local-to-global diagnostic of path incompatibility in synchronization dynamics.

New numerical methods for calculating statistical equilibria of two-dimensional turbulent flows, strictly based on the Miller-Robert-Sommeria theory

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31141v1 Announce Type: cross Abstract: New numerical methods are proposed for the mixing entropy maximization problem in the context of Miller-Robert-Sommeria's (MRS) statistical mechanics theory of two-dimensional turbulence, particularly in the case of spherical geometry. Two of the methods are for the canonical problem; the other is for the microcanonical problem. The methods are based on the original MRS theory and thus take into account all Casimir invariants. Compared to the methods proposed in previous studies, our new methods make it easier to detect multiple statistical equilibria and to search for solutions with broken zonal symmetry. The methods are applied to a zonally symmetric initial vorticity distribution which is barotropically unstable. Two statistical equilibria are obtained, one of which has a wave-like structure with zonal wavenumber 1, and the other has a wave-like structure with zonal wavenumber 2. While the former is the maximum point of the mixing entropy, the wavenumber 2 structure of the latter is nearly the same as the structure that appears in the end state of the time integration of the vorticity equation. The new methods allow for efficient computation of statistical equilibria for initial vorticity distributions consisting of many levels of vorticity patches without losing information about all the conserved quantities. This means that the statistical equilibria can be obtained from an arbitrary initial vorticity distribution, which allows for the application of statistical mechanics to interpret a wide variety of flow patterns appearing in geophysical fluids.

Hadronic exceptional points

Wed, 01 Jul 2026 00:00:00 -0400

arXiv:2606.31697v1 Announce Type: cross Abstract: Exceptional points, where eigenvalues and eigenvectors coalesce, are a defining feature of non-Hermitian systems and have been extensively observed in photonic, atomic, and condensed matter systems. However, they have received little attention in quantum chromodynamics (QCD), which is the fundamental theory of quarks, gluons, and hadrons. We propose that imaginary magnetic fields provide a simple realization of non-Hermitian dynamics in hadronic systems. Based on two theoretical approaches, a hadronic effective Lagrangian and a constituent quark model, we compute mass spectra of neutral mesons and find exceptional points separating the real-spectrum and complex-eigenvalue regimes. In small fields, the real spectrum exhibits level attraction between hadronic states, whereas in larger fields, hadrons are deconfined, which is a signature of a field-induced inverted potential. Our findings open a new avenue for studying QCD dynamics in non-Hermitian environments.

Energy-momentum tensor form factors and spin density distribution in the nucleon calculated in a quantized Skyrme model with vector mesons

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2603.11704v3 Announce Type: replace-cross Abstract: We investigate energy-momentum tensor (EMT) form factors and the spatial spin density distribution in the nucleon within a framework of the quantized Skyrme model with vector mesons. We construct both the canonical and Belinfante improved EMTs and analyze how pseudogauge uncertainty influences local spin and momentum densities while leaving the global nucleon properties unchanged. Using the inversion formulas from nucleon matrix elements in the forward limit, we extract the form factors, $A(t)$, $D(t)$, and $J(t)$, in both pseudogauges and the additional antisymmetric form factor associated with the canonical EMT. We find that the pseudogauge choice leads to sizable differences in the local spin and momentum densities. In particular, the canonical EMT naturally encodes spin density through the antisymmetric tensor structure, while the Belinfante EMT is sensitive to the total angular momentum only. Our results illustrate explicitly how different pseudogauges correspond to different spatial interpretations of nucleon spin structure within the same underlying dynamics. These findings provide a concrete model realization of the pseudogauge ambiguity in QCD-inspired nucleon structure and offer useful intuition for interpreting spatial distributions.

Weinberg Angle, Neutron Abundance in BBN, and Lifetime

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2603.02652v2 Announce Type: replace-cross Abstract: We present state of the art kinetic theory determination of the neutron abundance available for the Big-Bang nucleosynthesis (BBN). Our work is motivated by the study of the neutron lifespan measured in the laboratory and the unknown strength of weak interactions coupling constant $G_\mathrm{F}$ at finite temperature in the primordial Universe. We draw attention to the relevant dependence of $G_\mathrm{F}$ on the symmetry breaking Weinberg angle $s^2_\mathrm{W}$, a free parameter in the standard model of particle physics. We establish how the value of $s^2_\mathrm{W}$ by way of $G_\mathrm{F}$ modification influences neutron abundance available for BBN and neutron lifetime.

Exploring nuclear modification using one-point energy correlator at the electron-ion collider

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2512.16847v2 Announce Type: replace-cross Abstract: We study the one-point energy correlator (OPEC) at both the back-to-back and collinear limits in electron-proton and electron-nucleus collisions. We provide the factorization formalism for the two types of OPEC and present phenomenological predictions in the kinematic region relevant for the future Electron-Ion Collider. Focusing on cold nuclear matter effects in electron-nucleus scattering, we demonstrate that the OPEC serves as a powerful probe of the transverse momentum dependent (TMD) physics and in characterizing the medium-induced transverse momentum broadening in cold nuclear matter.

$\psi(2S)$ production in jets using NRQCD

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2508.00814v3 Announce Type: replace-cross Abstract: Based on recent data from LHCb, we study $\psi(2S)$ production in jets using non-relativistic QCD (NRQCD) in conjunction with the Fragmenting Jet Function (FJF) and Gluon Fragmentation Improved Pythia (GFIP) formalisms. Similar to previous studies of $J/\psi$ production in jets, our results show that these formalisms offer a much better description of data than the default Pythia+NRQCD prediction. We compare and contrast the predictions from the FJF formalism and the GFIP approach. In addition, our results show that the distribution of $\psi(2S)$ in jets is an excellent discriminator to test different predictions for the $\psi(2S)$ LDMEs from various extractions. We find a large disparity between the predictions from three different collaborations, showing that a more precise extraction of the $\psi(2S)$ LDMEs may be necessary.

Possible explanation of Hoehler's clustering: effective partial-wave mixing induced by truncation

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2604.26652v2 Announce Type: replace Abstract: Hoehler noted that resonance poles obtained from different partial waves in $\pi N$ scattering appear to bunch together near a small set of common complex energies, and suggested that this could indicate mixing between angular momenta. Here, we examine whether at least part of this pattern could arise effectively from the extraction procedure itself. Exact partial-wave unitarity preserves the separation of angular momenta in the infinite problem, whereas practical pole extraction from bilinear observables requires truncation of the partial-wave series. Combined with the truncation-induced mixing mechanism established in Ref.~\cite{Svarc2026}, this provides a natural source by which fitted partial-wave coefficients can inherit overlapping pole-bearing content, thereby offering a plausible contribution to Hoehler-type clustering.

Resonances extracted in truncated partial-wave analysis are effective mixtures of angular momenta (Possible implications for H\"ohler's clustering)

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2604.11472v2 Announce Type: replace Abstract: In truncated partial-wave analysis one fits observables, not amplitudes, and the relevant observables are bilinear in the amplitudes. For angle-dependent observables from which partial-wave content is inferred, truncation therefore does more than simply discard higher partial waves. The extracted lower partial waves are determined by a coupled nonlinear fit and need not be direct projections of the corresponding quantities in the full non-truncated problem. Instead, truncation reshuffles pole-bearing content among partial waves, including the nominally retained lower ones, so that a resonance contribution associated with one exact angular-momentum sector can reappear in several extracted partial waves and lose a unique angular-momentum assignment. We demonstrate this explicitly in a minimal scalar toy model, where a Hermitian bilinear represented by a Legendre series truncated at order 2 is fitted by another series truncated at order 1. Even in this simplest case, the fitted low-order coefficients depend on bilinear combinations involving higher-order parts of the original amplitude. Resonance-related quantities extracted from such a truncated analysis should therefore not, in general, be interpreted as resonances with definite angular momentum. We then discuss a possible phenomenological consequence for H\"ohler's observation that resonance poles assigned to different partial waves in $\pi N$ scattering tend to cluster near a few common points in the complex energy plane. If the extracted pole-bearing quantities are effective mixtures of several angular-momentum sectors, the inferred spectrum can naturally exhibit cross-wave correlations. In this sense, truncation provides a plausible contribution to H\"ohler-type clustering.

Construction of Nuclear Covariant Energy Density Functional from A Physics-Guaranteed Neural Network Approach

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.30326v1 Announce Type: new Abstract: Density functional theory is a practical approach for solving quantum many-body problems with available computational resources. The complexity of the nuclear force makes constructing an accurate nuclear energy density functional much more challenging. The feasibility of constructing a nuclear covariant energy density functional with deep neural networks is demonstrated. This physics-guaranteed neural network approach achieves high accuracy in predicting nuclear energy density and exhibits significantly better extrapolation abilities than traditional machine learning methods for binding energies. When combined with the existing covariant density functional, the neural network approach improves the binding energy accuracy from $644$ keV to $86$ keV in the known region and also effectively captures the microscopic shell effect. Furthermore, its extrapolation performance is also significantly enhanced, achieving an accuracy of approximately $5$ MeV even when extrapolating up to $30$ steps. This work paves the way for the construction of accurate nuclear energy density functionals through machine learning.

Interplay of quadrupole and octupole degrees of freedom in the Gd isotopes

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.30174v1 Announce Type: new Abstract: A systematic theoretical investigation of the quadrupole and octupole collective properties across the Gd isotopic chain is performed employing a quadrupole-octupole axially symmetric model. These nuclei have recently attracted significant attention following the revelation that the maximum octupole collectivity in this region is located at $^{150}$Gd. The model parameters are optimized by fitting to the low-lying positive and negative-parity energy levels, as well as to known $E0$, $E1$, $E2$, and $E3$ transition strengths. Our primary objective is a simultaneous and unified description of quadrupole and octupole collectivity across the even-even Gd nuclei in the $84\leqslant N \leqslant96$ range, a region that includes the transition from spherical to rotational nuclear shapes. The results show a smooth evolution of the quadrupole deformation, highlighted by a distinct jump at the well-known $N=90$ critical point. The enhancement of quadrupole deformation is also correlated with the loss of non-zero octupole deformation, which is reported only for the lightest $^{148,150}$Gd nuclei. This translates into a fair agreement with the measured $E3$ strength, predicting a maximum $B(E3)$ value for the $^{152}$Gd isotope.

Anisotropic hadronic rescattering and its impact on $K^{*0}$ yield, and polarization observable

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.30154v1 Announce Type: new Abstract: In this work, we investigate the anisotropic suppression of reconstructed $K^{*0}$ resonances arising from hadronic rescattering using the A Multi-Phase Transport (AMPT) model for Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV. We demonstrate that the rescattering probability of the decay daughters depends strongly on the decay angle $\theta^{*}$ due to Lorentz boost effects, which lead to smaller laboratory-frame momenta for daughters emitted opposite to the parent particle motion. This anisotropic suppression influences several experimentally measured observables. We show that the reconstructed $K^{*0}$ yield exhibits a strong $\theta^{*}$ dependence. Furthermore, the anisotropic loss of resonances modifies the angular distributions used to extract the spin alignment parameter $\rho_{00}$ in the production-plane and helicity frames. Even in the absence of intrinsic polarization in the model, the reconstructed $K^{*0}$ sample shows deviations of $\rho_{00}$ from the unpolarized value of $1/3$, with opposite trends in the two reference frames. These results demonstrate that hadronic rescattering can generate apparent polarization signals and must be carefully considered in experimental measurements of vector-meson spin alignment using production plane and helicity frame.

Quark and hybrid stars with renormalization group improvement of NNLO perturbative QCD

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.29576v1 Announce Type: new Abstract: Recently, the NNLO perturbative QCD pressure of cold and dense symmetric matter, with arbitrary quark masses, has been resummed within the renormalization-group-optimized perturbation theory (RGOPT) framework. By being imbued with renormalization group properties, the resulting pressure is less sensitive to renormalization scale ($\Lambda\equiv X \mu_B/3$) variations than the NNLO perturbative QCD pressure. Here, we extend this by considering $\beta$-equilibrium and charge neutrality to evaluate the corresponding equation of state (EoS). We provide a compact ``pocket" fitting formula for the EoS for $N_f=2+1$ massive quarks at different renormalization scale parameter ($X$) values. We describe pure quark stars as well as hybrid stars with quark-cores. Pure quark stars compatible with astrophysical observations were obtained with $X=3.08-3.58$, whereas a larger value (4.10) is needed if the low mass object of the observation GW190814 represents a neutron star. Hybrid stars were built considering three representative hadron models based on a relativistic mean-field description, and chosen to produce soft and stiff EoSs. Stable hybrid stars with masses compatible with the massive pulsar PSR J0740+6620 were obtained considering $X$ of the order of 2 to 2.60-2.98, the largest scale giving rise to hybrid stars with a large quark core with a radius of 5 to 8 km, and the smallest to a small quark core at the center of the star.

Quartet Structure Above $^{100}$Sn and $^{132}$Sn Doubly Magic Isotopes

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.29283v1 Announce Type: new Abstract: We calculate energy levels and B(E2) values for the $\alpha$-like nuclei $^{104}$Te and $^{136}$Te. Their energy structure is described within a Multi Step Shell Model (MSM) type approach by coupling proton-proton (pp), neutron-neutron (nn) and proton-neutron(pn) phonon states over the doubly magic nuclei $^{100}$Sn and $^{132}$Sn, respectively. We also compute the electric transitions for A = 102 and A = 134 Sn, Sb and Te nuclei, described within the Tamm-Dankoff Approach (TDA) with multipole-multipole residual interaction. The encountered similarities concerning the B(E2) values and wavefunctions of the coupled states corresponding to $^{104}$Te and $^{136}$Te are analyzed.

Embedded Random Matrix Ensembles to Statistical Shell Model: Operation of $q$-normal forms

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.29210v1 Announce Type: new Abstract: Embedded random matrix ensembles operating in nuclear shell model spaces, with nucleons occupying a finite set of single particle orbits and interacting via a two-body interaction, form the basis for statistical shell model. With sufficiently strong interaction, the level densities in shell model spaces take close to a Gaussian form and transition strength distributions close to a bivariate Gaussian form. In practice, partitioning via spherical configurations ($\tilde{m}$) and angular momentum $J$ (also isospin where appropriate) are essential. The resulting statistical spectroscopy or statistical shell model was applied successfully in the past in some studies of nuclear level densities, orbit occupancies, $\beta$-decay matrix elements and so on. Going beyond these, recently it is recognized that embedded ensembles, in a better approximation, generate in-fact $q$-normal form ($q=1$ gives Gaussian and $q=0$ Wigner's semi-circle) for density of eigenvalues, bivariate $q$-normal form for transition strengths and conditional $q$-normal form for strength functions. These then allow us to develop statistical shell model with $q$-normal forms. These new developments in embedded ensembles and statistical shell model are briefly reviewed in this paper. Also described, using some examples, is the role of the $q$ parameter in generating statistical properties of general quantum many-particle systems.

Revisiting identified-particle $p_{\mathrm{T}}$ spectra using the Boltzmann-Gibbs blast-wave model in a Bayesian inference framework

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.29187v1 Announce Type: new Abstract: We perform a Bayesian analysis of transverse momentum ($p_{\mathrm{T}}$) spectra of identified particles, i.e., pions, kaons, and protons, at midrapidity in Au+Au collisions and Pb+Pb collisions using the Boltzmann-Gibbs blast-wave (BGBW) model. We investigate whether it is possible to simultaneously describe the $p_{\mathrm{T}}$ spectra of identified particles without imposing the particle species-dependent $p_{\mathrm{T}}$ fit ranges -- a practice that was followed in conventional blast-wave model studies to achieve reasonable simultaneous fits. Using Bayesian analysis, our results indicate that a simultaneous description of the $p_{\mathrm{T}}$ spectra of pions, kaons, and protons is feasible without imposing the particle species-dependent $p_{\mathrm{T}}$ fit ranges, for Au+Au collisions up to the available data ($\sim$2 GeV/c) and for Pb+Pb collisions up to 3 GeV/c. The extracted parameters remain broadly consistent with those obtained from conventional BGBW simultaneous fits, while the extension of the fit range leads to moderate changes in some parameters. Furthermore, Bayesian analysis yields well-constrained posterior distributions for the kinetic freeze-out temperature $T_{kin}$, the average transverse flow velocity $\langle \beta_{\mathrm{T}}\rangle$, and the exponent of the velocity profile $n$ and shows their correlations transparently. We suggest that the BGBW model in a Bayesian inference framework proposed can be applied in future data analyses to simultaneously describe the $p_{\mathrm{T}}$ spectra of identified particles and extract the relevant information about the collision system.

The Confined beta-Soft rotor model in rare-earth nuclei

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.12264v2 Announce Type: replace-cross Abstract: Contemporary theoretical descriptions of nuclear structure rely mainly on microscopic, single-particle frameworks often in competition with collective degrees of freedom, especially when deformation plays a dominant role. Such phenomena are prominent in the rare-earth region, where rotational band structures and enhanced electric quadrupole transitions are systematically examined. The Confined beta-Soft (CBS) rotor model, introduced by N. Pietralla and O.M. Gorbachenko, bridges the gap between the X(5) critical point and the rigid-rotor limit in the region where the R_4/2 = E(4+)/E(2+) ratio lies between 2.904 and 3.333. In the present work, the CBS framework is employed to calculate ground-state band energies, associated B(E2) transition rates, and beta-band excitations of even-even nuclei in the rare-earth region. The theoretical results are systematically compared with available experimental data, and predictions are provided for nuclear observables that have not yet been measured, offering guidance for future experimental investigations.

A cryogenic gas target for high-intensity radioactive ion beam production at HIRFL-RIBLL

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.04139v2 Announce Type: replace-cross Abstract: A liquid-nitrogen-cooled cryogenic gas target system has been developed and installed for radioactive ion beam (RIB) production at the Radioactive Ion Beam Line in Lanzhou (RIBLL). Light-element gases ($\mathrm{H}_2$, $\mathrm{D}_2$, and $^4\mathrm{He}$) filled in the target cell were cooled to cryogenic temperatures, with the gas-cell outlet temperature typically monitored at 82--86 K during beam irradiation and operating pressures up to 1000 mbar. The system was used to produce $^{7}\mathrm{Be}$, $^{16}\mathrm{N}$, and $^{15}\mathrm{O}$ RIBs via the $^{1}\mathrm{H}(^{7}\mathrm{Li}, ^{7}\mathrm{Be})n$, $^{2}\mathrm{H}(^{15}\mathrm{N}, ^{16}\mathrm{N})p$, and $^{1}\mathrm{H}(^{15}\mathrm{N}, ^{15}\mathrm{O})n$ inverse kinematics reactions, yielding purities of 85\%, 99\%, and 95\%, with intensities of $1.02\times10^{6}$, $2.7\times10^{5}$, and $1.0\times10^{5}$ pps, respectively. A $^{93m}\mathrm{Mo}$ isomer beam was also produced via the $\mathrm{^4He(^{94}Zr,} 5n)^{93m}\mathrm{Mo}$ reaction, achieving an intensity of $5.38\times10^{3}$ pps and a purity of 20\% (which can be further improved to $\sim$50\% with offline time-of-flight gating). By delivering a broader range of high-intensity secondary RIBs, this setup establishes a robust platform at RIBLL for low- and medium-energy nuclear astrophysics and reaction studies.

Toward a Unified Understanding of the Dense Matter Equation of State

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2511.20378v2 Announce Type: replace-cross Abstract: Efforts to understand the equation of state (EOS) of dense nuclear matter at supra-saturation densities have grown more sophisticated over the past decade, driven by a surge in high-precision data from both terrestrial experiments and astrophysical observations. While for the former, heavy-ion collisions (HIC) represent a unique opportunity to constrain the EOS in a controlled laboratory setting, the latter can be precisely probed thanks to the advent of multi-messenger astronomy (MMA). However, as we move away from understanding drawn from individual sources and limited statistics to the era of precision physics with improved datasets, the need for a systematic way to combine them becomes clear. In this article, we trace the individual methods for extracting the EOS both for HIC and MMA. We then review the current state-of-the-art collaborative efforts to combine these individual sources of information, focusing on: the Nuclear Physics and Multi-Messenger Astrophysics (NMMA) framework, which relies on Bayesian inference methods; the Modular Unified Solver for the Equation of State (MUSES) calculation engine, which integrates EOS priors with HIC data and produces predictions for key neutron star properties; and the Bayesian Analysis of Nuclear Dynamics (BAND) framework, which uses cutting-edge Bayesian methods to produce reliable and trustworthy predictions for nuclear and astrophysical problems. We highlight the scientific advances with respect to the EOS and neutron star properties made possible by each framework and outline the remaining challenges that must be addressed to build a coherent, predictive picture of dense nuclear matter across all relevant regimes. We conclude with a detailed discussion of how these frameworks might be integrated with each other to form a unified workflow for future EOS predictions.

Calculation of Particle Pair Correlation Functions with Classical Trajectory Approximation

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2510.23030v3 Announce Type: replace-cross Abstract: Femtoscopic interferometry is a powerful tool for probing the spatio-temporal evolution of emission sources in heavy-ion collisions. A major challenge in the field is formulating a self-consistent description of the source function, final-state interactions between the particle pair, and interactions inherent to the source itself. To address this, we have developed a novel Monte Carlo model for calculating two-particle correlation functions in a classical trajectory approximation (CTA-I). The model incorporates self-consistently the emission source of thermal equilibrium and three-body final state interactions. Application of the model shows satisfactory fit to experimental data, revealing that the correlation function is highly sensitive to the source's spatio-temporal extent. In contrast, the temperature parameter governing the emitted particles' energy spectra has a negligible influence. Our approach offers the potential to extract the spatio-temporal information from the emission source, thereby advancing the applicability of femtoscopic interferometry in the Fermi energy domain.

Bayesian Analysis with Markov Chain Monte Carlo for Global Optimization and Degeneracy Diagnosis in Nuclear Mass Models

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.30519v1 Announce Type: cross Abstract: We employ a full Bayesian analysis with adaptive Metropolis-Hastings Markov chain Monte Carlo (BA-MCMC) sampling to systematically study the posterior probability distributions of the strengths of energy terms in optimized nuclear mass models of Bethe-Weizs\"{a}cker variants. Strong correlations of some energy terms for some mass models are revealed through the parameter degeneracy diagnosis. We analyze selected refined models to determine parameter degeneracies while proposing a new macroscopic-microscopic mass model, BWL, which considers quadrupole and high-multipole deformation and shell corrections. All mass models in this work are analyzed and optimized through the BA-MCMC method. Compared with 2242 precise experimental binding energies of AME2020, BWL produces a root-mean-square deviation of 759 keV, particularly improving the description of masses in the light-nuclei and actinide regions. BA-MCMC offers robust inference on parameter degeneracy while providing an optimization method for future nuclear mass models.

Nuclear equation-of-state at high density and multi-messenger astronomy: contribution of heavy-ion collisions

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.29588v1 Announce Type: cross Abstract: In the past decades, heavy-ion collisions (HIC) at intermediate energies have allowed to probe the nuclear equation-of-state (EoS) of both symmetric and asymmetric nuclear matter over a broad range of densities. In particular, flow has proven to be a powerful observable. Combining the symmetry energy and the symmetric nuclear matter constraints of the EoS from HIC allowed to predict a density dependence of the pressure in a neutron star, up to about 2.5 times saturation density ($n_{sat}$), which agrees with recent astronomical measurements deduced from gravitational waves and pulsar observations. So far, the accuracy from HIC expectations is comparable to the latter up to 1.5 $n_{sat}$. In these studies, a fundamental aspect is the determination of the profile of densities that are probed by experimental observables used to constrain the EoS. In the near future, new experiments like ASY-EOS performed at higher incident energy and with better accuracy will push further the frontier of the knowledge of the symmetry energy at higher density. These efforts cannot be conclusive without a reliable uncertainty determination, which is related to the reliability of transport model dependencies. Improvements and breakthroughs in transport model simulations and nuclear theory are therefore expected in a joint effort towards HIC contributions to the field of neutron-star physics, including the contribution of strangeness and of the QCD phase transition.

Self-Supervised Calibration of Scientific Instruments Using Physical Consistency Constraints

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.29466v1 Announce Type: cross Abstract: Calibration remains one of the principal obstacles to the deployment of machine learning in scientific instrumentation because it typically relies on expert intervention, dedicated procedures, and manually labelled data. We introduce a physics-informed self-supervised framework that jointly learns latent detector calibration parameters and task-specific predictions directly from raw measurements without requiring pre-calibrated signals or external labels. The method exploits known physical constraints to generate pseudo-labels iteratively, transforming calibration into a self-supervised optimization problem. The approach is demonstrated for ionic charge-state determination in the VAMOS++ magnetic spectrometer, where the calibration of a segmented ionization chamber and the inference of ionic charge states are learned simultaneously. Starting from a weak prior on the mean ionic charge state, the model progressively refines its predictions through iterative fractional pseudo-labelling driven by the discrete nature of atomic masses. Beyond accurate ionic charge-state reconstruction, the inferred calibration coefficients provide a compact representation of the detector state that enables automated monitoring of gain drifts, pressure variations, and detector aging. The resulting labels can subsequently be transferred to specialized models that quantify detector imperfections and track their spatial and temporal evolution. These results establish a general paradigm for self-calibrating and self-monitoring scientific instruments and represent a step toward intelligent experimental systems capable of autonomous calibration, analysis, and performance optimization.

Thermal and electromechanical response of ultra-thin carbon-strip polarimeter targets in relativistic bunched beams

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.29005v1 Announce Type: cross Abstract: Thin carbon-strip targets provide fast relative hadron beam polarimetry, but their response in intense relativistic bunched beams is not governed by local stopping-power heating alone. We develop a coupled response model that combines beam-target overlap, secondary-electron escape, retained heat, target motion, transient heat transport, RF-induced strip-end heating, beam-induced forces, resistance changes, and slack-strip deformation. RHIC target observations constrain the relevant motion, force, and nonlocal-heating scales and show that target survival depends on both beam-center heating and electromagnetic boundary conditions near the strip ends. Applying the model to Booster, AGS, RHIC, and EIC proton and $^{3}\mathrm{He}$ cases shows that the RHIC proton lifetime scale is reproduced at the order-of-magnitude level, while the RHIC target-holder fin results require the additional RF/end-heating mechanism. For EIC proton flattop operation, carbon-strip polarimetry may remain viable only with reduced dwell time, sufficient detector acceptance, and suppression of RF-induced end heating. For cooled-emittance $^{3}\mathrm{He}$, the calculated sublimation-loss scale is far beyond a straightforward RHIC-like carbon-strip extrapolation. Conventional carbon strips are therefore unlikely to remain viable for the most demanding EIC light-ion cases without major changes in target motion, target technology, or diagnostic concept.

Multistage dynamical modeling of heavy-ion collisions

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.22315v1 Announce Type: cross Abstract: Relativistic heavy-ion collisions create deconfined QCD matter whose properties must be inferred from final-state observables through dynamical modeling. This contribution discusses recent progress and open issues in multistage simulations, with emphasis on the connection between bulk evolution, conserved charges, strangeness, and heavy flavor. At RHIC Beam Energy Scan energies, the breaking of longitudinal boost invariance makes charge stopping and rapidity-dependent observables essential for constraining the finite-density medium. Strange hadrons are sensitive to the local chemical environment and conserved-charge correlations, while heavy flavor probes microscopic transport and hadronization. Combining these observables within multi-sector inference frameworks provides a path toward more robust constraints on the equation of state and transport properties of QCD matter.

Precision measurement of radiative neutron \b{eta}-decay: methodology and systematic effects

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.30205v1 Announce Type: new Abstract: In the Standard Model the free neutron decays to a proton, an electron, and an antineutrino along with a continuous spectrum of photons. In 2016 the RDK II collaboration reported on a measurement of the photon energy spectrum and branching ratio over the range of 0.4 keV to the 782 keV endpoint using two different detector arrays. In the experiment, the radiative decay photons were observed in coincidence with the decay electrons and protons. In this paper, we present details of the analysis, including the determination of the systematic corrections and uncertainties and comparison of measured particle and photon energy spectra to Monte Carlo simulations. We conclude with approaches to improving the precision of these measurements.

Spiral, target, stripe, and disordered waves in active six-state Potts models

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2604.22353v2 Announce Type: replace-cross Abstract: Wave propagation can be observed in various nonequilibrium systems. In this study, we investigated the properties of several wave modes in active six-state Potts models using Monte Carlo simulations of square and hexagonal lattices. Disordered and spiral (SP) waves of six states are formed under weak and strong repulsions at nonflip contacts, respectively. The target (TG) and stripe (ST) waves were found to emerge under stronger repulsion. These three wave modes (SP, TG, and ST) can temporally coexist in small systems near the transition points but they do not switch in large systems or far from these transition points. During coarsening from randomly mixed states to ST waves, SP waves appear at an intermediate stage. The SP wave modes of three even- or odd-numbered states (states $s=0,2,4$ or $s=1,3,5$) emerge under two conditions: repulsion at the diagonal contact and attraction at nonflip contacts. Previously thought to be identical for both conditions, the wave types were found to differ, comprising forward and backward waves ($s=1\to 3\to 5\to 1$ or $s=1\to 5\to 3\to 1$), whose domain boundaries move by the two-step and four-step forward flips, respectively. The transition between the waves of the even- and odd-numbered states is first-order for both the forward and backward waves.

Quantization and Biphoton Statistics of k-Gap Solitons in Nonlinear Photonic Time Crystals

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.30508v1 Announce Type: cross Abstract: Nonlinear photonic time crystals (PTCs) can support solitons inside momentum k gaps, where the amplification of k gap modes is saturated by Kerr nonlinearity, forming spatially homogeneous but temporally localized excitations. Yet their quantum nature remains unclear. Here we quantize nonlinear k gap dynamics of PTCs and show that k gap solitons are represented by biphoton Fock ladder states. K gap amplification drives two-mode squeezing of the biphoton, while Kerr nonlinearity generates an anharmonic potential along the biphoton Fock ladder that balances this squeezing process, creating a finite biphoton number turning point and giving rise to quantum collapse and revival dynamics and nonclassical phase space interference. We further analyze how photon loss and dephasing reshape the biphoton statistics of quantized k gap solitons. Our results establish a biphoton Fock space description of k gap soliton quantization and provide a framework for studying quantum nonlinear excitations and entangled light generation in photonic time crystals.

Bifurcation structure of soliton self-injection locking in microresonators

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.29921v1 Announce Type: cross Abstract: Self-injection locking (SIL) of a diode laser to a high quality-factor microresonator has recently become increasingly important in hybrid integrated photonics, providing access to compact sub-Hz linewidth lasers. It was also shown to facilitate the access to dissipative Kerr solitons - the key to a low-noise coherent frequency comb on a photonic chip. However, the existence and stability ranges of SIL soliton states in experimentally controlled parameters are still not fully understood. Here we study the bifurcation structure of solutions in a model of soliton SIL in the weak-backscattering limit. We show that SIL produces soliton-number-dependent existence ranges of multi-soliton solutions in free-laser detuning and feedback phase parameters. We identify exclusive single-soliton existence regions and demonstrate dynamical access to single solitons in this region by direct numerical simulations using prescribed parameter sweeps.

Kinetic equations for a two-dimensional soliton gas

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.30582v1 Announce Type: new Abstract: We formulate a general system of kinetic equations for a non-stationary two-dimensional gas of elastically interacting line solitons and apply it to the description of a soliton gas governed by the Kadomtsev-Petviashvili II (KPII) equation. We then verify the predictions of the kinetic theory in two analytically tractable problems: the oblique interaction of a KPII line soliton with a one-dimensional soliton condensate of the Korteweg-de Vries equation, and the interaction of a trial KPII soliton with a monochromatic KPII soliton gas. In both cases, we compare the analytical results with direct numerical simulations obtained by constructing two-dimensional soliton gases via exact KPII $N$-soliton solutions for large $N$, using appropriately chosen random distributions of soliton parameters. The comparison demonstrates excellent agreement, thereby providing strong validation of the proposed kinetic theory of 2D non-equilibrium soliton gases.

Physical Analogue Kolmogorov-Arnold Networks based on Reconfigurable Nonlinear-Processing Units

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2602.07518v3 Announce Type: replace-cross Abstract: Kolmogorov-Arnold Networks (KANs) shift neural computation from linear layers to learnable nonlinear edge functions, but implementing these nonlinearities efficiently in hardware remains an open challenge. Here we introduce a physical analogue KAN architecture in which edge functions are realized in materia using reconfigurable nonlinear-processing units (RNPUs): multi-terminal nanoscale silicon devices whose input-output characteristics are tuned via control voltages. By combining multiple RNPUs into an edge processor and assembling these blocks into a reconfigurable analogue KAN (aKAN) architecture with integrated mixed-signal interfacing, we establish a realistic system-level hardware implementation that enables compact KAN-style regression and classification with programmable nonlinear transformations. Using experimentally calibrated RNPU models and hardware measurements, we demonstrate accurate function approximation across increasing task complexity while requiring fewer or comparable trainable parameters than multilayer perceptrons (MLPs). System-level estimates indicate an energy per inference of roughly 200 pJ and an end-to-end inference latency of roughly 0.6 $\mu$s for a representative workload, corresponding to over 100$\times$ reduction in energy accompanied by $>$10$\times$ reduction in area compared to a digital fixed-point MLP at similar approximation error. These results establish RNPUs as scalable, hardware-native nonlinear computing primitives and identify analogue KAN architectures as a realistic silicon-based pathway toward energy-, latency-, and footprint-efficient analogue neural-network hardware, particularly for edge inference.

On the role of higher-order interactions towards first synchronization time

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2604.07707v2 Announce Type: replace Abstract: This study investigates transient collective dynamics, with a focus on how higher-order interactions impact the time required to reach steady-state synchronization. Assuming a large ensemble of deterministic and globally coupled Kuramoto oscillators with Cauchy-distributed natural frequencies, an expression for the first synchronization time is derived using the Ott-Antonsen ansatz. Subsequent numerics reveal that (i) increasing the coupling strengths for a fixed interaction order accelerates the transition to synchronization and (ii) increasing the interaction order for fixed interaction strength produces non-monotonic behavior. In particular, the inclusion of triadic interactions generally accelerates synchronization, whereas further higher-order interactions progressively delay convergence to the steady state, in some regimes even falling below the pairwise level. Ultimately, for very large interaction orders, the dynamics revert to pairwise-like behavior. Simulations of the system equations for different parameter combinations support these observations, while the asymptotic case is interpreted through the nonlinear structure of the order-parameter dynamics.

Spike-frequency and h-current based adaptation are dynamically equivalent in a Wilson-Cowan field model

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2510.08436v4 Announce Type: replace Abstract: During slow-wave sleep, the brain produces traveling waves of slow oscillations (SOs; $\leq 2$ Hz), characterized by the propagation of alternating high- and low-activity states. The question of internal mechanisms that modulate traveling waves of SOs is still unanswered although it is established that it is an adaptation mechanism that mediates them. One mechanism investigated is spike-frequency adaptation, a hyperpolarizing feedback current that is activated during periods of high-activity. An alternative mechanism is based on hyperpolarization-activated currents, which are positive feedback currents that are activated in low-activity states. Both adaptation mechanisms were shown to feature SO-like dynamics in neuronal populations, and the inclusion of a spatial domain seems to enhance observable differences in their effects. To investigate this in detail, we examine a spatially extended two-population Wilson-Cowan model with local spatial coupling and the excitatory populations equipped with either one of the two adaptation mechanisms. We describe them with the same dynamical equation and include the inverse mode of action by changing the signs of adaptation strength and gain. We show that the dynamical systems are mathematically equivalent under a compensatory external input, which depends on the adaptation strength, leading to a shift in state space of the otherwise equivalent bifurcation structure. Strong enough adaptation is required to induce traveling waves. Additionally, adaptation modulates the properties of the spatio-temporal activity patterns, such as temporal and spatial frequencies, and the speed of the traveling waves, all of which increase with increasing strength. Though being dynamically equivalent, our results also explain why location-dependent variations in feedback strength cause differences in the propagation of traveling waves between both adaptation mechanisms.

Exact Evolution Law for Action-Weighted Path Ensembles and the Dynamics of Self-Organization

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2507.02209v4 Announce Type: replace Abstract: Self-organizing open systems sustained by source--sink fluxes transform stochastic motion into ordered behavior, yet a general dynamical criterion governing this process has not been established. This paper derives an exact kinematic law for evolving action-weighted canonical path ensembles, and decomposes the dynamics of the ensemble-average action. In the precision-driven regime, the evolution closes: the rate of change is governed by the action variance, so increasing selectivity concentrates probability weight toward lower-action trajectories, causing the average action to decrease monotonically and behave as a Lyapunov-type quantity. Constant and decreasing selectivity lead to stationary and broadening behavior. Endogenous reduction of the average action defines self-organization, while externally prescribed modulation defines controlled ensemble evolution. The framework further admits system-dependent realizations of selectivity dynamics, including reconstruction from observable statistics and feedback-driven evolution, without modifying the underlying kinematic law. By using stochastic action as the organizing trajectory-level quantity, the approach connects path-ensemble organization to stochastic least-action ordering while yielding measurable diagnostics, finite-time constraints, and falsifiable signatures in open stochastic systems.

Kuramoto meets Koopman: Constants of motion, symmetries, and network motifs

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2504.06248v5 Announce Type: replace Abstract: Conserved quantities in phase-oscillator dynamics are well established for identically coupled oscillators, or groups thereof, but the explicit connectivity conditions under which more complex networks admit constants of motion remain difficult to identify. Using Koopman theory, we derive general conditions for the existence of distinct conserved quantities in the Kuramoto model with heterogeneous phase lags on any weighted, directed, and signed graph. To this end, we find Koopman eigenfunctions and continuous Lie symmetries that generate different families of constants of motion. The derived conditions reveal a broad class of network motifs that support conserved quantities and we detect these motifs in hundreds of complex empirical networks. The results thus point to connectivity patterns that can preserve phase relationships over time and motivate further investigations of Koopman spectral properties for dynamics on complex networks.

Pulses, waves, and cascades in collective migration dynamics

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.30604v1 Announce Type: cross Abstract: Decisions to migrate depend on others' decisions. Dependence can produce nontrivial dynamics. We propose a minimal migration model that accounts for social influence alongside individual heterogeneity in mobility as migrants move from region to region. In special locations of parameter space, migrant flows dramatically and spontaneously fluctuate. Such aspects mimic observed fluctuations in migration statistics and thus show how large fluctuations in data can reflect more than response to events like armed conflict and natural disasters. Correspondingly, the impact of exogenous factors can be confounded with the results of collective decisions.

Bidirectional Autoregressive Latent Diffusion for Forward and Inverse Magnetohydrodynamics

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.29620v1 Announce Type: cross Abstract: This work presents a new bidirectional autoregressive latent diffusion approach for predicting the evolution of multiple fields (mass density, pressure, velocity, and magnetic field components) for magnetohydrodynamics. We show that this bidirectional flow can be used as a self-supervised consistency metric for uncertainty and error estimation, which enables the model to estimate test-time uncertainty and error without access to ground truth, by comparing how closely flowing forwards and backwards in time returns to the same predicted fields. We also demonstrate this methods's potential to serve as a non-invasive plasma diagnostic, and show how adaptive feedback can be used to make the model more robust based on sparse diagnostics or limited views/measurements.

Drift Behavior in a Bounded-Confidence Opinion Model with Media Influence

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.28318v1 Announce Type: cross Abstract: People's opinions can change both from their interactions with each other and from their interactions with media sources. Bounded-confidence models (BCMs) of opinion dynamics provide one framework to study such dynamics. In a BCM, the nodes of a network are agents with continuous-valued opinions, and these agents interact with each other via the edges of the network. In this paper, we extend the original Deffuant--Weisbuch (DW) BCM by incorporating influence from two media sources -- one with a positive value and one with a negative value -- to capture the effects of a polarized media landscape. We show both numerically and analytically that our extended DW model exhibits drifting behavior in which a large cluster of opinions shifts toward one of the media agents. We analyze how the drift trajectory and speed depend on the model parameters, and we identify conditions in which drift is promoted or suppressed. Our results provide insight into how competing media sources can influence collective opinion formation in social systems.

Nonlinear nature of near-equilibrium viscous fluids

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.30043v1 Announce Type: cross Abstract: We study the late-time relaxation of a neutral relativistic viscous fluid in $d+1$ dimensions. In the long-wavelength regime, linearized hydrodynamics predicts that the sound mode at momentum $nk$ decays as $e^{-n^2\omega_I t}$. However, nonlinear analysis gives a decay of $e^{-n\omega_I t}$. We derive a closed asymptotic attractor solution in which the frequency of the $n$-th harmonic locks to $n$ times the complex frequency of the fundamental mode. The amplitude envelopes for energy current $J$ obey a simple cascading relation, $J_n=\alpha_J^{\,n-1}J_1^n$, with $\alpha_J$ fixed by the equation of state, the longitudinal viscosity, and the fundamental wavenumber. For conformal fluids, $\alpha_J=1/(8\eta k)$, in agreement with the holographic result of arXiv:2512.07242. The existence of the attractor shows that, even near equilibrium, field powers are not equivalent to amplitude order.

Quantifying Influence and Information Transfer in a Modified Vicsek Model with Non-reciprocal Interactions

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2506.20888v4 Announce Type: replace-cross Abstract: Understanding information transfer among individuals is fundamental to revealing the collective dynamics of complex systems. Information transfer has been quantified using various information-theoretic tools and assigned the concept of influence. However, information-theoretic measures are inherently statistical, not causal, and influence in the context of causal inference implies a causal relation, so equating influence with information transfer creates conceptual confusion and interpretational challenges. Here, we introduce an influence-based Vicsek model with non-reciprocal interactions to distinguish influence from information transfer and examine their relationship. At the pairwise level, for fixed noise strengths, influence and transfer entropy exhibit quasi-linear relations; for fixed interaction weights, influence and transfer entropy exhibit nonlinear relations. At the collective level, we find that both influence and normalized transfer entropy form two-branched relations that clearly identify the transition points across three distinct phase transitions. These transition points reveal a different aspect of the collective dynamics not captured by classical order parameters: phase transitions are associated with changes in the relative importance of influencers' presents or followers' presents on followers' futures. Finally, we use our model to assess partial information decomposition methods and identify two methods most suitable for analyzing our system, one based on pointwise surprisal changes and the other on secret key agreement. Our work is a first step in distinguishing the concept of influence from information transfer in a physical model system, provides a concrete testbed for methods emerging from the growing field of information theory-based causal inference, and offers new insights into the dynamics of complex systems.

Entropic Time, Psychophysics, and Deformed Neural Dynamics: A Unified Physical Theory for Human Time Perception

Tue, 30 Jun 2026 00:00:00 -0400

arXiv:2606.29427v1 Announce Type: cross Abstract: We present a unified physical theory demonstrating that human subjective time perception does not track geometric coordinate time $t$, but instead emerges from a local metric mutation driven by macroscopic physical entropy production. By establishing the Nonextensive Troika -- a closed, mutually dependent algebraic triplet linking the phase-space fractal dimension $D$, the conformable derivative order $\alpha$, and the Tsallis nonextensive parameter $q$ -- we eliminate independent phenomenological fitting constants. We prove that the local time metric inherently scales as $t^{\alpha}$, deriving the conformable operator as a necessary kinetic consequence. Furthermore, we derive the $q$-index from the equiprobable monofractal Tsallis entropy $S_q$. This structural closure unifies anomalous neural dissipative transport within a deformed leaky integrate-and-fire framework and analytically predicts macroscopic psychophysical response transitions, providing a clear thermodynamic basis for time dilation in psychedelic states (the REBUS model) and temporal compression during cognitive aging.

Quantized Irreversible Null-geometry: Foundation and Applications

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.22788v2 Announce Type: replace-cross Abstract: Formulating a consistent integration measure for quantum geometric fluctuations without violating diffeomorphism invariance remains a theoretical challenge. In this work, a framework rooted in the statistics of discrete Poisson point processes is proposed. The formulation yields a double-exponential probability functional characterized by a capacity limit, which acts as an amplitude regularizer suppressing ultraviolet singularities. To evaluate this model at macroscopic scales, a statistical bifurcation of the stochastic action is identified. First, the macroscopic mean condenses to define the classical continuous spacetime background and its matter distribution. Second, at macroscopic scales, the Law of Large Numbers dictates that the residual ultraviolet noise maps into an infrared continuous zero-mean Gaussian martingale within the bulk. Third, this zero-mean Gaussian noise linearly generates standard quantum kinematic effects. Fourth, evaluating the non-linear exponential action separates the variance of this Gaussian noise from the linear cancellation, rectifying it into a macroscopic drift that manifests as the dark energy density. Diluted by the Bekenstein-Hawking entropy of the observable universe, this bulk variance dictates a continuous field cutoff at 6 TeV. Building upon this framework, broad phenomenological applications are demonstrated: (1) establishing a UV-finite effective field theory preserving gauge symmetries in 4D; (2) constructing a topological model of particles deriving Standard Model hierarchies; (3) formulating a non-singular cosmological model predicting observed large-scale power suppression in the cosmic microwave background; and (4) deriving foundational axioms of quantum mechanics as emergent statistical phenomenologies. Collectively, this framework provides a falsifiable synthesis bridging discrete quantum geometry and continuous macroscopic physics.

Principles and Possibilities for Bound States in Gauge Theory

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.08489v2 Announce Type: replace-cross Abstract: Bound states differ from scattering yet are not covered in textbooks on Quantum Field Theory. I discuss a perturbative method for QED and QCD based on canonical quantization. Fully fixing temporal gauge $A^0(t,\boldsymbol{x})=0$ imposes Gauss' law on physical states. As pointed out by Dirac, this implies that electron states include a longitudinal gauge field $\boldsymbol{A}_L$, which determines the instantaneous bound state potential. The situation is analogous for quarks and gluons in QCD. An instantaneous confining potential arises for color singlet $q\bar q$ states when a non-vanishing boundary condition on $\boldsymbol{A}_L^a(\boldsymbol{x}\to\infty)$ is specified in Gauss' constraint. As suggested by Gribov, $\alpha_s(Q^2)$ may freeze at a perturbative value when the confining potential dominates. Hadrons can then be calculated perturbatively. At vanishing quark mass there is a $j^{PC}=0^{++}$ state with zero energy which can mix with the perturbative vacuum, giving rise to a spontaneous breaking of chiral symmetry.

Forward trijet production in proton-nucleus collisions: gluon initiated channel

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2604.07509v2 Announce Type: replace-cross Abstract: In this paper, we present results for the forward three-parton production differential cross section in the gluon-initiated channel in proton-nucleus collisions. This result is the leading-order contribution to forward trijet production and provides the real-emission building block required for the NLO dijet/dihadron cross section. The calculations are carried out within the Color Glass Condensate (CGC) effective theory, and in the dilute-dense approximation, using effective vertices for the quark and gluon propagators interacting with the small-$x$ background gluon field. We employ the covariant perturbation theory approach and disentangle the amplitudes into regular and instantaneous contributions. Our results are expressed as convolutions of multiparton color correlators of light-like Wilson lines and perturbative impact factors, organized in compact expressions in terms of the ``bare" topologies of the contributing diagrams. The gluon-initiated channel receives contributions from a $q\bar{q}g$ and a $ggg$ final state. Interestingly, when considering the $ggg$ final state, we observe, for the first time, that the four-gluon vertex topology follows a structure similar to the instantaneous contributions. This observation suggests a simplification in the organization of multigluon CGC amplitudes and may prove useful for future one-loop calculations. Furthermore, when integrating (one of) the real gluon(s) in the final state, we identify that the rapidity divergence is absorbed into the real part of the JIMWLK evolution of the leading-order Wilson-line correlator. In addition, we isolate the divergences arising when the unobserved parton becomes collinear to one of the observed hadrons in the final state. These divergences are absorbed by renormalizing the initial-state parton distribution functions and final-state fragmentation functions, which are shown to obey DGLAP evolution.

Momentum Broadening in the Opacity Expansion: All-Path-Length Corrections and Improved Regge Kinematics

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2602.16450v2 Announce Type: replace-cross Abstract: We present a detailed study of momentum broadening and the jet transport coefficient $\hat{q}$ for high-energy partons traversing the Quark-Gluon Plasma (QGP), extending the Gyulassy-Levai-Vitev (GLV) formalism to include both all-path-length (APL) and sub-Regge kinematical corrections. Traditional GLV calculations rely on the large separation distance and large formation time approximations, which are valid for large systems but whose applicability to small systems, such as $pp$ and $p/d$A collisions, may fail. We derive analytic expressions for the momentum broadening distributions and $\hat{q}$ to first order in the opacity expansion, and perform a detailed numerical investigation to quantify their impact. The APL correction suppresses momentum broadening at low $p_{\perp}$, with a correction scaling as $\propto 1/(L\, p_{\perp})$ that dominates for small systems, while converging to the standard GLV result at large $L$. The sub-Regge kinematical correction enhances momentum broadening at high $p_{\perp}$, becoming significant when the transverse momentum transfer approaches the magnitude of the parton's large light-cone momentum component, and vanishing in the Regge limit where this ratio is small. When both corrections are combined, the sub-Regge kinematical correction partially mitigates the suppression induced by the APL term; in the case of $\hat{q}$, this mitigation is essentially complete, with $\hat{q}_{(\mathrm{APL+SUB})}$ found to coincide closely with the standard GLV result. These findings demonstrate that sub-Regge kinematical corrections can resolve the long-standing problem of large negative energy-loss contributions at high energies identified in earlier studies.

Revisiting the soft-hard separation in the transverse momentum spectra of $pp$ collisions

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2510.09692v2 Announce Type: replace-cross Abstract: We study the separation of soft and hard components in the transverse momentum spectra of charged particles as measured by ALICE in proton-proton collisions at $\sqrt{s}$ = 2.76, 5.02 and 13 TeV at the LHC. The soft component is described by a Boltzmann fit, while the residual spectra are identified as a hard QCD-like fragmentation contribution. After separation, the subtracted spectra show no significant evolution in shape or peak position with multiplicity, consistent with a two-component interpretation. Mean transverse momenta for both contributions remain nearly constant across multiplicity classes, while Pythia 8 Monte Carlo simulations confirm these trends. The robustness of the decomposition is demonstrated by a comparison between simulations with and without color reconnection, yielding consistent results. The terms `soft' and `hard' are used as operational labels within this framework and should not be interpreted as uniquely identified dynamical components. Our results are consistent with the two-component description as a viable and physically motivated alternative to hydrodynamical interpretations.

Quantum Late-Time Decay and Channel Dependence

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2509.17163v2 Announce Type: replace-cross Abstract: Quantum mechanics predicts deviations from exponential decay at short and long times, yet experimental evidence is limited. We report a power-law tail after $\sim$10 lifetimes in two fluorescent compounds (erythrosine~B and eosine Y), confirmed by two detectors probing distinct bands but yielding different power coefficients. The data match a divergent but normalizable spectral density, and theory predicts oscillations as a future test. A novel and general result is that in multichannel QM (and QFT) decay, the lifetime is universal, but the late-time deviations are channel- (or band-) dependent, a feature consistent with our data.

Dense and Cold Magnetized Quark Matter: A Review of Magnetic-Field-Independent Regularization and the Medium Separation Scheme

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.28111v1 Announce Type: cross Abstract: We present a comprehensive review of regularization schemes for magnetized dense quark matter within effective models of quantum chromodynamics, focusing on the Magnetic-Field-Independent Regularization (MFIR) and the Medium Separation Scheme (MSS) at finite chemical potential and magnetic field. In nonrenormalizable frameworks such as the Nambu-Jona-Lasinio model, the treatment of ultraviolet divergences is crucial, particularly in magnetized and dense environments where conventional regularization procedures may introduce unphysical artifacts. We show that MFIR consistently isolates divergent vacuum contributions from finite magnetic-field-dependent terms, while MSS extends this separation to the medium sector, ensuring that only vacuum quantities are regularized. Within this unified framework, we analyze the thermodynamics of cold and dense quark matter, including color-superconducting phases, and demonstrate that the superconducting gap remains finite at large chemical potentials, even in the presence of strong magnetic fields. In contrast to results obtained with traditional regularization schemes, we find no evidence for a transition to a normal phase at zero temperature, highlighting the importance of a proper separation between vacuum and medium contributions. These results eliminate spurious oscillations and other nonphysical artifacts, leading to a more robust and physically consistent description of strongly interacting matter under extreme conditions relevant to compact stars and heavy-ion collisions.

The QCD phase diagram for three-flavor M\"obius domain-wall fermions

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.28086v1 Announce Type: cross Abstract: We investigate the phase transition of Quantum Chromodynamics (QCD) with three degenerate quark flavors at zero baryon chemical potential. Using M\"{o}bius domain-wall fermions as the lattice fermion formulation, we ensure excellent chiral symmetry preservation. Our simulations are performed at three different temporal lattice extents, $N_{t}=6, 8, 12$, with a fixed lattice spacing $a=0.1361(20)$ fm, corresponding to temperatures of 242(4), 181(3), and 121(2) MeV, respectively. We explore a range of quark masses and spatial volumes with aspect ratios $N_{s}/N_{t}$ spanning from 2 to 4. By analyzing the mass and volume dependencies of the plaquette, plaquette susceptibility, chiral condensate, chiral susceptibilities, and Binder cumulant, we identify the pseudocritical transition quark masses from our largest lattice volumes. For $N_t=6$, this is 184(10) MeV (determined from the plaquette susceptibility). For $N_t=8$ and 12, the transition points vary slightly depending on whether the total or disconnected chiral susceptibility is used, yielding ranges of 36(1)-39.1(9) MeV and 3.5(3)-3.7(2) MeV, respectively, in the $\overline{\text{MS}}$ scheme at a scale of $\mu=2$ GeV. The negligible volume dependence at $N_t=6$ and 8, combined with finite-size scaling analysis at $N_t=12$ revealing volume growth significantly weaker than expected for a first- or second-order phase transition, points to a continuous crossover at these specific quark mass points. Additionally, we study the effects of residual chiral symmetry breaking on the chiral condensate and chiral susceptibilities using two different values of $L_s$.

From the quark parton model to QCD

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.27618v1 Announce Type: cross Abstract: The quark parton model grew out of deeply inelastic scattering experiments. The parton model developed into a full theory, quantum chromodynamics, QCD. This article explains some of the physics issues encountered in connecting the parton model and QCD.

Bridging Ab Initio Symmetries and Global Nuclear Masses with Interpretable Neural Networks

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.28287v1 Announce Type: new Abstract: Ab initio modeling has established Wigner's SU(4) and Elliott's SU(3) as dominant symmetries of the nuclear force in light and intermediate-mass nuclei. We ask whether they also govern nuclear binding across the entire chart. Our aim is not high-precision prediction but physical insight, through interpretable, symmetry-based models. From the SU(3) and SU(4) Casimir operators we construct three neural-network (NN) mass models: Feature-Informed NN (FINN) for point predictions, Gaussian-Informed NN (GINN) adding uncertainty quantification, and Wigner-Informed NN (WINN) -- a mass formula using the Casimirs as an operator basis. All are trained on AME2016 and validated on nuclei new to AME2020. The SU(4) operators alone cut the root-mean-square error (RMSE) by nearly half on train and test data, and by about a fifth on extrapolation, relative to the liquid-drop baseline -- showing that Wigner's symmetry carries predictive information beyond bulk properties. Despite its compact form, WINN reaches the lowest validation RMSE, 0.430 MeV -- competitive with state-of-the-art mass models -- which we read less as a benchmark than as evidence that its symmetry basis captures important physics. WINN further reveals i) an enhancement of the quadratic SU(4) Casimir near the neutron dripline, signaling restoration of Wigner's symmetry, and ii) an unexpected gain of the quartic operator in the superheavy region. We thereby elevate emergent symmetries from the hidden order within individual nuclei to a governing principle of the whole nuclear chart.

QCD critical surface from constant entropy contours

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.28282v1 Announce Type: new Abstract: We provide the first mapping of the critical surface in (2+1)-flavor QCD in the full $(T,\mu_B,\mu_Q,\mu_S)$ space, anchored on lattice QCD results at vanishing chemical potentials and obtained within an expansion along contours of constant entropy density. In the pure $\mu_B$ direction, this framework yields a critical point at $(T_c,\mu_{B,c}) \simeq (114,\, 602)$ MeV. Here we extend the construction to arbitrary directions in the three-dimensional chemical-potential space, parametrized by spherical coordinates $(\mu,\theta,\varphi)$, with the radial expansion truncated at $\mathcal{O}(\mu^2)$. The resulting two-dimensional surface carries a direction-dependent critical temperature $T_c(\theta,\varphi)$ and baryochemical potential $\mu_{B,c}(\theta,\varphi)$, which quantify the shift of the critical point relative to the pure $\mu_B$ direction. We find that $\mu_{B,c}$ increases by 40-100 MeV along the approximately strangeness neutral direction [$\mu_S \approx (0.15$--$0.33)\, \mu_B$, $\mu_Q \approx 0$] relevant for heavy-ion collisions, while the critical temperature stays essentially unchanged. In the charge-neutral, weak-equilibrium direction~[$\mu_Q \approx -(0.05$--$0.1) \,\mu_B$, $\mu_S = 0$] relevant for neutron star mergers, the critical point, and the associated first-order phase transition, remain present at essentially the same location in the $(T,\mu_B)$ plane. We find no evidence for a critical point at large isospin densities, $|\mu_Q| / \mu_B \gtrsim 1$, relevant for cosmic trajectories in the early Universe, nor along the pure electric-charge or strangeness directions, at least outside the regions where pion or kaon condensation may occur.

Efficient calculation of two-neutrino double-beta-decay nuclear matrix elements

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.28224v1 Announce Type: new Abstract: Reliable nuclear matrix elements (NMEs) are essential for interpreting double-beta-decay experiments and for connecting measured or constrained half-lives to the underlying weak-interaction physics. The two-neutrino mode ($2\nu\beta\beta$) is allowed by the Standard Model and has been observed in several nuclei, whereas the neutrinoless mode ($0\nu\beta\beta$) remains the key experimental signature of lepton-number violation and Majorana neutrino masses. Recent statistical shell-model studies indicate a strong correlation between the $2\nu\beta\beta$ and $0\nu\beta\beta$ NMEs, making accurate and efficient calculations of the former especially useful for assessing the latter. Direct evaluations of $2\nu\beta\beta$ NMEs usually require summing over many $1^+$ states in the intermediate odd-odd nucleus, a procedure that becomes expensive and may converge slowly in large model spaces. We present and test an improved strength-function method based on Lanczos iterations that avoids full diagonalization while preserving the accuracy of explicit summation where such benchmarks are possible. The method is applied to several experimentally important emitters and to different effective Hamiltonians. We also show that the same framework can be used for the higher-order NMEs entering Taylor-expanded phase-space treatments of $2\nu\beta\beta$ and related decay modes.

Universal EOS-Radius Inverse Mappings Govern Precision-Dependent Inference of the Neutron Star Equation of State

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.28183v1 Announce Type: new Abstract: Bayesian inference of the neutron star (NS) equation of state (EOS) generally assumes that improved observations primarily reduce posterior uncertainties while leaving inferred EOS parameters unchanged. Using mock measurements of the radius of a canonical $1.4\,M_\odot$ NS with identical central values but varying observational precisions, we show that the inferred posterior means of EOS parameters can shift systematically as the measurement uncertainty changes. We demonstrate that this behavior originates from previously unidentified nearly universal inverse mappings between the NS radius $R_{1.4}$ and empirical EOS parameters. Across a broad range of observational precisions, posterior samples collapse onto nearly unique functions. These mappings are largely independent of observational precision and define a low-dimensional EOS manifold underlying Bayesian inference. We show that the precision dependence of inferred EOS parameters arises from nonlinear filtering of the posterior radius distribution through these mappings. In the narrow-distribution limit this effect reduces to a Jensen-type correction proportional to the local curvature of the inverse mapping, while for presently realistic uncertainties the full nonlinear-filtering relation accurately reproduces the posterior means. Our results reveal a geometric origin of precision-dependent inference in NS EOS studies and provide a new framework for connecting astrophysical observations directly to microscopic nuclear many-body theories.

Oblate-prolate shape mixing and E0 transition in 28Si

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.27631v1 Announce Type: new Abstract: Background: oblate-prolate shape coexistence in $^{28}$Si has been discussed for decades, but the degree of shape mixing between these configurations remains poorly constrained. Purpose: We constrain the oblate-prolate mixing amplitudes in $^{28}$Si using available experimental information and discuss the inter-band E0 transition strength. Methods: Oblate and prolate $0^+$ and $2^+$ configurations are obtained by antisymmetrized molecular dynamics combined with the generator coordinate method. Using these configurations as the basis states, we constrain the mixing amplitudes by simultaneously reproducing the measured charge radius, the quadrupole moment of the $2_1^+$ state, and the in-band and inter-band $B(\mathrm{E2})$ values. The strength of the density-dependent term in the Gogny interaction is also varied within a reasonable range. Results: In the ground state, the oblate component is dominant, and the prolate component in the ground state is limited to less than about $20\%$. For the $2_1^+$ state, the allowed prolate component is smaller than that in the ground state. The present analysis does not tightly constrain the corresponding E0 transition strength, but an upper limit of $\rho^2(\mathrm{E0};0_3^+\rightarrow0_1^+) \lesssim 0.206$ is obtained. Conclusions: The low-lying $0^+$ states of $^{28}$Si may exhibit substantial oblate-prolate mixing. A measurement of the inter-band E0 transition strength would provide a quantitative determination of the mixing amplitude.

Floquet Recurrences in the Double Kicked Top

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2511.13342v2 Announce Type: replace-cross Abstract: We study exact quantum recurrences in the double kicked top (DKT), a driven spin model that extends the quantum kicked top (QKT) by introducing an additional time-reversal symmetry-breaking kick. Reformulating its dynamics in terms of effective parameters $k_r$ and $k_\theta$, we analytically show exact periodicity of the Floquet operator for $k_r = j\pi/2$ and $k_r = j\pi/4$ with distinct periods for integer and half-odd integer $j$. These exact recurrences were found to be independent of $k_\theta$. The long-time-averaged entanglement and fidelity rate function show dynamical quantum phase transition (DQPT) for $k_r = j\pi/2$ at time-reversal symmetric cases $k_\theta = \pm k_r$. In the other time-reversal symmetric case $k_\theta = 0$, the DQPT exists only for a half-odd integer $j$. Using level statistics, a smooth transition is observed from integrable to non-integrable nature as $k_r$ is changed away from $j\pi/2$. Our work demonstrates that regular and chaotic regimes can be controlled for any system size by tuning $k_r$ and $k_\theta$, making the DKT a useful platform for quantum control and information processing applications.

On dynamic multi-agent pathfinding methods: review, simulations and modifications

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.03735v2 Announce Type: replace Abstract: This paper presents a systematic study of pathfinding algorithms in the context of Dynamic Multi-Agent Pathfinding (D-MAPF), a setting that combines dynamic obstacles, partial observability, and inter-agent conflicts. We evaluate six representative algorithms: Dijkstra, D* Lite, Space-Time A*, WHCA*, M*, and a novel method denoted as A** within a unified simulation framework. The proposed A** algorithm introduces a template-based approach that decouples offline geometric path generation from online temporal adaptation. By precomputing multiple diverse candidate paths and dynamically reconnecting to them using space-time planning, A** improves solution quality in environments with frequent changes and limited sensing

Statistical equilibria of two-dimensional turbulent flows for generic initial vorticity fields on a sphere, calculated on the basis of the original Miller-Robert-Sommeria theory

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2606.27778v1 Announce Type: cross Abstract: Based on the original Miller-Robert-Sommeria theory, we explicitly compute a statistical equilibrium of two-dimensional turbulent flow on a sphere for a generic initial vorticity field introduced in a previous study. The macroscopic vorticity field corresponding to the obtained statistical equilibrium has a quadrupole structure. The resulting quadrupole structure is topologically consistent with the final state of the long-term time integration of the vorticity equation. However, the statistical equilibrium does not predict the formation of concentrated vortices as seen in the time integration. We also calculate statistical equilibria for the initial vorticity field with a planetary vorticity term, and find a change of statistical equilibria from quadrupole states to zonally symmetric states as the angular velocity of the sphere increases. The quadrupole statistical equilibria show nearly linear relations between the macroscopic vorticity and the macroscopic stream function, implying that higher-order Casimir invariants are virtually ineffective even when all Casimir invariants are considered. The discrepancy between the equilibria and the time integration results emphasizes the importance of mixing barriers, which prevent the relaxation of the evolving vorticity field to the statistical equilibria and allow the point-vortex-like dynamics of coherent vortices to persist.

How Withheld Punishment Enables Authoritarian Persistence: An Evolutionary Dynamics Approach

Mon, 29 Jun 2026 00:00:00 -0400

arXiv:2512.06245v3 Announce Type: replace-cross Abstract: Democratic backsliding is often framed as a contest between pro-democratic defenders and anti-institutional norm-breakers. That framing can miss a third behavior, a public that withholds punishment from norm-breakers while penalizing those who confront them. We study a minimal three-strategy evolutionary game, with institutional defenders, anti-institutional disruptors, and this non-punishing public evolving under replicator dynamics. We grant defenders a head-to-head advantage over disruptors and ask whether it guarantees their long-run success. It does not. Two payoff regimes, differing only in how the public and disruptors interact, produce two failure modes. In an exploitation regime, the public is harmed by disruptors yet withholds sanction, so the three strategies exhibit cyclic dominance. When the losses around the cycle outweigh the gains, every interior trajectory approaches a boundary heteroclinic cycle in which disruptors repeatedly resurge. In an accommodation regime, the public and disruptors each gain from their interaction. When the public's gain is large enough, every interior trajectory converges to a stable public-disruptor coalition that excludes defenders. A pro-democratic advantage is therefore not enough. Weak sanction and penalized confrontation can leave anti-institutional disruption recurring or entrenched.

Radioactive Molecules as Laboratories of Fundamental Physics

Thu, 25 Jun 2026 00:00:00 -0400

arXiv:2605.12767v2 Announce Type: replace-cross Abstract: Radioactive molecules provide a powerful new platform in the search for new physics at energy scales complementary to high-energy particle colliders. By combining enhancements from nuclear properties with the sensitivity and control offered by molecular structure, experiments with radioactive molecules offer great reach in the search for new physics beyond the Standard Model. Rapid progress in this field is being driven by advances in the production and control of radioactive molecules, alongside the development of new experimental tools and theoretical techniques. In this Perspective, we discuss the current status and future prospects of this rapidly developing, interdisciplinary field at the intersection of nuclear physics, atomic and molecular physics, and particle physics.

Positron-Emitting and Electron-Capturing Double-Beta Processes in the Standard Model and Beyond

Thu, 25 Jun 2026 00:00:00 -0400

arXiv:2606.26097v1 Announce Type: cross Abstract: We study positron-emitting and electron-capturing double-beta-decay modes as probes complementary to the usual double beta decay. Motivated by the proposed NuDoubt++ experiment, we analyze the candidate isotopes ${}^{78}$Kr, ${}^{106}$Cd, and ${}^{124}$Xe, providing nuclear matrix elements and phase-space factors for both neutrinoful and neutrinoless modes. For the Standard-Model channels, we find that $2\nu$ECEC and $2\nu\beta^+$EC are the most experimentally accessible, whereas $2\nu\beta^+\beta^+$ remains strongly phase-space suppressed. For the neutrinoless channel, we interpret a projected sensitivity of $T_{1/2}^{0\nu} = 10^{24}$ y in terms of dimension-seven SMEFT operators and find sensitivity to lepton-number-violating new-physics scales of order 1-100 TeV. We further show that measurements in multiple isotopes can help to resolve degeneracies in multi-operator scenarios, making positron-emitting double-beta searches a useful complement to conventional neutrinoless double beta decay experiments.

The renormalization of the shell-model neutrinoless double-beta decay operator starting from effective field theory (I)

Thu, 25 Jun 2026 00:00:00 -0400

arXiv:2606.25486v1 Announce Type: cross Abstract: In this work, we approach for the first time the task to perform a shell-model calculation of the matrix element for the neutrinoless double-beta decay, within a fully-consistent framework where the expressions of the nuclear Hamiltonian and of the decay operators have been derived through chiral perturbation theory. More precisely, the effective shell-model Hamiltonian and all transition operators have been constructed by way of the many-body perturbation theory, and then employed to calculate both spectroscopic properties of the nuclei involved in the decays under our consideration - namely 48Ca, 76Ge, and 82Se -, as well as the nuclear matrix elements of the electromagnetic and neutrinoless double-beta decays. We also present a study of the convergence properties of the calculated matrix elements in order to provide the elements for an estimate of the theoretical uncertainty.

Ab initio calculations of parity-violating electron scattering off $^{48}$Ca and $^{208}$Pb

Thu, 25 Jun 2026 00:00:00 -0400

arXiv:2606.25019v1 Announce Type: cross Abstract: Parity-violating electron scattering off nuclei both serves as a low-energy precision probe to test electroweak interactions and allows one to access neutron distributions inside nuclei. It has implications for strong interactions in dense neutron-rich environments, also providing constraints for the properties of matter in neutron stars. Precision measurements are available for $^{48}$Ca and $^{208}$Pb by the CREX and PREX collaborations, respectively, and their interpretation requires advanced nuclear-structure calculations to draw firm conclusions. We perform the first ab initio calculations of the parity-violating asymmetry $A_\text{PV}$ based on nuclear forces from chiral effective field theory, fully including corrections due to Coulomb distortion effects. Based on these results, we critically reexamine correlation analyses employed to infer weak radii and quantify the resulting tensions between ab initio and experimental results. We find that ab initio calculations prefer values of $A_\text{PV}$ slightly smaller and larger than observed for $^{48}$Ca and $^{208}$Pb, respectively, with a global significance of $1.9\sigma$. Using theoretically consistent inputs for charge and weak densities, we infer from the experimental $A_\text{PV}$ a neutron skin of $^{208}$Pb of $R_n-R_p = 0.187(25)(18)$ fm, substantially smaller than that reported by PREX II.

Empirical-Bayes Unfolding of $\gamma$-ray Spectra

Thu, 25 Jun 2026 00:00:00 -0400

arXiv:2606.24971v1 Announce Type: cross Abstract: Unfolding observed $\gamma$-ray spectra is an ill-conditioned Poisson inverse problem. Detector response effects and finite energy resolution make distinct non-negative emitted $\gamma$-ray spectra nearly indistinguishable after forward mapping, so direct inversion can strongly amplify statistical fluctuations. Here, we present an empirical-Bayes hierarchical unfolding method that preserves the Poisson counting structure, enforces non-negativity, and incorporates background through a joint ON/OFF likelihood. The prior on the emitted spectrum is centered on an automatically selected Richardson-Lucy reference spectrum, with an adaptive width that remains broad in weakly constrained regions. Posterior inference is performed with the No-U-Turn Sampler, and simultaneous uncertainty bands are reported for the resolution-limited unfolded spectrum. Our Bayesian method provides a robust and extensible framework for uncertainty quantification in unfolding, and a direct comparison with a recent frequentist regularized maximum-likelihood method gives highly consistent unfolded spectra in representative high- and low-statistics cases.

The $B(E2)$ anomaly: Evidence for a low-lying mixed-symmetry collective excitation mode

Wed, 24 Jun 2026 00:00:00 -0400

arXiv:2512.11555v3 Announce Type: replace-cross Abstract: Exceptionally low values of the ratio of electric quadrupole transition rates, $B_{4/2}\equiv B(E2;4^+_1\rightarrow2^+_1)/B(E2;2^+_1\rightarrow0^+_{\mathrm{gs}})<1$, have been observed in neutron-deficient nuclei near $N\approx94$ (W, Os, Pt) and $N\approx62$ (Te, Xe) with few and comparable numbers of valence nucleons outside closed shells. Remarkably, the suppressed $B_{4/2}$ ratios coincide with low-lying energy level patterns characteristic of collective motion. Standard approaches, including large-scale shell model, collective models, and density functional theory, fail to reproduce this behavior, commonly referred to as the $B{4/2}$ (or $B(E2)$) anomaly. Recent work has reproduced the effect in selected Pt and Os isotopes via mapping a triaxial rotor Hamiltonian onto the interacting boson model (IBM), attributing it to triaxial rotational motion. However, this interpretation is unexpected as collectivity typically emerges first through vibrational modes with increasing valence nucleon number along isotopic chains. Here, we address this discrepancy using an extended IBM Hamiltonian across nuclei exhibiting the anomaly, benchmarked against large-scale shell model calculations, and propose that the $B(E2)$ anomaly arises from a low-lying mixed-symmetry collective mode that bridges single-particle and collective dynamics.

A convex-geometric framework for fully phase-locked states in the finite Kuramoto model

Wed, 24 Jun 2026 00:00:00 -0400

arXiv:2604.14772v2 Announce Type: replace-cross Abstract: We study the finite-size Kuramoto model of all-to-all coupled phase oscillators with heterogeneous natural frequencies and characterize the minimal coupling strength required for the existence of a fully phase-locked equilibrium (in a co-rotating frame). To remove the degeneracy due to uniform phase shifts, we move to a reduced co-rotating frame and assess stability through the Jacobian of the reduced system: a fully phase-locked state is stable when this Jacobian is negative definite. This defines a stability region in the phase space. The Kuramoto vector field maps this region to a convex set in frequency space, so a fully-locked state at coupling $K$ exists exactly when the rescaled frequency vector $\hat{\mathbf{\omega}}/K$ lies inside that convex image. The critical coupling $K_{\ell}$ is defined as the smallest coupling strength for which a fully phase-locked equilibrium exists; geometrically, it corresponds to the first intersection of the ray $t\hat{\mathbf{\omega}}$ with the boundary of this convex set. Building on this convex-geometric structure, we construct an explicit polytope from analytically computable boundary points of the stability region, providing a closed-form upper bound $K_b \ge K_{\ell}$. The bound is exact for frequencies aligned with polytope vertices and offers a fully explicit outer approximation for general frequency vectors. While not uniformly sharp in a quantitative sense, this construction exposes the underlying geometry of stable fully phase-locking solutions. These results provide a practical use the convex-geometric structure underlying stable fully-locked states in the Kuramoto model.

Emergence of higher-order interactions in systems of coupled Kuramoto oscillators with time delay

Wed, 24 Jun 2026 00:00:00 -0400

arXiv:2512.16193v2 Announce Type: replace Abstract: We show that higher-order interactions naturally emerge from time-delayed pairwise coupling in Kuramoto oscillators. By expanding the delayed pairwise coupling to the second order, we derive a delay-free Kuramoto model possessing both pairwise and three-body interactions. Numerical simulations and stability analysis demonstrate that the three-body Kuramoto model and the time-delayed pairwise Kuramoto model exhibit qualitatively consistent synchronization transitions under appropriate conditions. In particular, the bistability arising in the time-delayed Kuramoto model is accounted for by the three-body interactions. Our findings reveal that time delays can be recast effectively as higher-order interactions, providing an insight into how coupling delays shape collective dynamics.

Interlayer Synchronisation of Time-Varying Multiplex Kuramoto--Sakaguchi Networks in the Chimera Regime

Wed, 24 Jun 2026 00:00:00 -0400

arXiv:2111.12753v2 Announce Type: replace Abstract: We study interlayer synchronisation in a duplex network of $N=300$ nonlocally coupled Kuramoto--Sakaguchi oscillators, with each layer operating in the chimera regime. The interlayer coupling is weak ($\sigma_{12}=0.01$), sparse, and time-varying: a fixed number $N_{IL}$ of replica-node pairs are coupled symmetrically, and the active links are randomly redistributed every $T_{swt}$ time units. We characterise synchronisation by the time-averaged interlayer order parameter $Z$, the master stability function $\Psi(\sigma_{12},T_{swt})$, and the finite-time transverse Lyapunov exponent $\lambda_\perp$. In the static case, full synchronisation ($Z=1$, $\Psi<0$) requires all-to-all interlayer coupling ($N_{IL}=N$). Under temporal switching with $T_{swt}\leq 25$, near-complete synchronisation is achieved with as few as $N_{IL}\approx N/3$ links, while the intralayer chimera structure is preserved. The master stability function confirms that short switching periods render the transverse dynamics stable at link densities where static coupling fails, and the transverse Lyapunov exponent heatmap delineates the critical link number as a joint function of $N_{IL}$ and $T_{swt}$. These results demonstrate that temporal redistribution of sparse interlayer connections can stabilise replica-node coherence in networks with spatially heterogeneous intralayer dynamics.

Effective hyperuniformity in time-integrated stochastic Turing patterns

Wed, 24 Jun 2026 00:00:00 -0400

arXiv:2606.23677v1 Announce Type: cross Abstract: Demographic noise generates stochastic Turing patterns even when reaction-diffusion systems are deterministically stable. We show analytically and verify numerically in the Levin-Segel model that temporal integration of configurations reveals emergent large-scale organization. The intensive number variance in a window of size $R \gg 1$ approaches a finite reaction-kinetic floor as $1/R$, over a spatial range growing by orders of magnitude near the Turing instability. This yields an effectively hyperuniform, fine-tuning-free regime previously unidentified in non-conserved multispecies stochastic systems.

Universal Dynamical Response to Slow Driving in Chaotic Systems

Wed, 24 Jun 2026 00:00:00 -0400

arXiv:2606.23810v1 Announce Type: cross Abstract: We propose a unified perspective on classical and quantum chaos based on the stability of a system's stationary states under slow driving. We probe this sensitivity via the system's susceptibility to the average protocol speed, which we call the ``speed-Fisher information," and relate it to irreversible entropy production in the system. We show that chaotic dynamics manifests as a divergence of the speed-Fisher information with the protocol time, and that this response is controlled by the perturbation's low-frequency spectral weight. This approach to chaos applies to both classical and quantum Hamiltonian systems, and naturally extends to non-Hamiltonian classical flows. We illustrate this framework with simple classical and quantum examples, along with a non-Hamiltonian flow that qualitatively exhibits analogous low-frequency spectral behavior.

Attractor reconstruction in attracting subspaces: Slow-spectrum preshaping for reservoir computing under partial observation

Wed, 24 Jun 2026 00:00:00 -0400

arXiv:2606.24303v1 Announce Type: new Abstract: Data-driven reproduction of chaotic dynamics under partial observation remains a challenge despite its practical importance. Reservoir computing (RC) and other data-driven approaches often succeed in short-term prediction, yet they are sensitive to hyperparameters and fail to reproduce the long-term statistical properties of the system. We identify one cause of this failure: the reconstructed attractor set is placed in a transversally unstable region of the representation space. We therefore propose a design principle for RC that introduces a few slow modes into its evolution rule in advance, so that a designated attracting low-dimensional subspace retains the history of the input series. We show that this achieves attractor reconstruction in attracting subspaces (ARAS) and, without relying on a posteriori performance-based tuning, enables robust prediction and reproduction of chaos under partial observation.

All-charm tetraquarks at hadron colliders: A high-precision fragmentation perspective

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2604.11646v2 Announce Type: replace-cross Abstract: We present the TQ4Q2.0 fragmentation functions for the production of all-heavy (fully heavy) $S$-wave tetraquarks ($T_{4Q}$) with scalar ($0^{++}$), axial-vector ($1^{+-}$), and tensor ($2^{++}$) quantum numbers in high-energy hadronic collisions. This work extends the previous TQ4Q1.1 framework by incorporating nonconstituent heavy-quark contributions and introducing a replica-based uncertainty-quantification strategy derived from multi-scale variations (MHOUs). The construction follows a nonrelativistic QCD factorization approach, combining gluon- and heavy-quark-initiated fragmentation channels at leading power. Initial-scale inputs are modeled through updated potential-inspired wave functions, while the subsequent DGLAP evolution is performed via the threshold-aware HF-NRevo scheme. A comprehensive systematic analysis of uncertainties is carried out, with contributions from color-composite long-distance matrix elements (LDMEs) and perturbative multiscale inputs. The resulting TQ4Q2.0 grids, publicly released in LHAPDF6 format, provide the first complete phenomenological set for all-heavy exotics, enabling precise studies of all-charm tetraquark production and jet-associated observables within the JETHAD environment. This article completes the high-energy resummation-driven generation of the TQ4Q program and establishes a definitive baseline for future collider-oriented analyses of all-heavy multiquark dynamics.

Adiabatic Fast Passage Spin Manipulation Measurements in Solid Polarized Targets

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2604.02365v3 Announce Type: replace-cross Abstract: Adiabatic fast passage (AFP) is a rapid method for reversing nuclear polarization and manipulating spin populations in polarized solid targets, avoiding the long repolarization times associated with dynamic nuclear polarization (DNP). We report AFP measurements in a 5~T, 1~K polarized-target system for irradiated $^{15}$NH$_3$, irradiated $^{14}$ND$_3$, and butanol-based materials prepared either with TEMPO doping or by irradiation. We also present a joint manipulated-lineshape analysis for spin-1 targets and demonstrate that vector and tensor polarizations can be extracted from AFP-manipulated deuteron NMR spectra even when the populations are not described by a single Boltzmann spin temperature. Finally, we report a reproducible polarization- and direction-dependent AFP response in a large irradiated $^{15}$NH$_3$ sample. These ammonia results are presented as empirical observations under the specific sample-coil conditions of the experiment, with possible circuit-mediated mechanisms such as radiation damping or superradiant behavior discussed but not assigned as a definitive cause.

Chiral three-nucleon forces for the new local position-space two-nucleon potential in $\textit{ab initio}$ many-body calculations

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2601.08199v2 Announce Type: replace-cross Abstract: Three-nucleon force (3NF) plays an important role in understanding the structure of finite nuclei and the saturation properties of infinite nuclear matter. More specifically, 3NF should be necessary for each two-nucleon force (2NF) to obtain more accurate description of nuclear systems. 3NF derived from the chiral effective field theory has been successful in $\textit{ab initio}$ calculations of atomic nuclei. Most of established chiral nuclear forces have a nonlocal form in the momentum space. In this work, we construct a companion chiral 3NF specifically tailored to the new Idaho local position-space 2NF, and calculate binding energies and radii of nuclei up to $^{132}$Sn. We find that a chiral 3NF with hybrid local and nonlocal regulators has advantages in improving the nuclear structure calculations of both binding energies and radii with the new Idaho 2NF. The two low-energy constants of 3NF are constrained by the ground-state energies of $^3$H and $^{16}$O as suggested in a recent work.

Search for dark matter Particles via Invisible Decays in ${}^{46}$Sc Nuclear $\gamma$ Cascades with a CsI(Tl) Detector

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2510.23001v4 Announce Type: replace-cross Abstract: Dark matter remains one of the most compelling open problems in modern physics, motivating experimental searches for new light, weakly coupled particles beyond the Standard Model. Despite extensive efforts employing diverse detection strategies, large regions of parameter space remain unexplored. We report a high-statistics laboratory search for invisible decay modes in nuclear $\gamma$-ray cascades using approximately $100~\mathrm{kg}$ of CsI(Tl) scintillators operated at Texas A\&M University. The experiment employs a high-activity ${}^{46}$Sc radioactive source and a ``missing-$\gamma$'' technique, in which the absence of a photon from a well-identified cascade serves as a signature of new physics. Unlike appearance-disappearance experiments, this approach requires only a single photon conversion into a dark-sector particle, enabling sensitivity to significantly weaker couplings. The setup provides simultaneous sensitivity to a broad class of light dark-sector candidates, including axions and axion-like particles, dark scalars, and dark photons in the $0.1 - 1 \text{ MeV}$ mass region. Through careful control of detector containment, energy resolution, and environmental backgrounds, we exclude certain regions on the previously explored parameter space. With foreseeable improvements in detector volume and systematic uncertainty control, this technique has the potential to probe currently unexplored parameter space for axion-like particles and light dark scalars.

Flavor, transverse momentum, and azimuthal dependence of charged pion multiplicities in SIDIS with 10.6 GeV electrons

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2510.03562v4 Announce Type: replace-cross Abstract: Measurements of SIDIS multiplicities for $\pi^+$ and $\pi^-$ from proton and deuteron targets are reported on a grid of hadron kinematic variables $z$, $P_{T}$, and $\phi^{*}$ for leptonic kinematic variables in the range $0.3

Vibrational Modes in Strongly Deformed Nuclei

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2507.20275v2 Announce Type: replace-cross Abstract: Low-energy vibrational excitations associated with the fluctuation of quadrupole deformed shapes are discussed within the frame of state-of-the-art Configuration Interaction calculations, actually performed via the Quasi-particle Vacua Shell Model version of the Monte Carlo Shell Model. Recently, low-lying $\gamma$ bands in heavy strongly deformed nuclei were shown to be rotational $K^P$ = 2$^+$ excitations of triaxially deformed states (see T. Otsuka \etal, Eur. Phys. J. A 61, 126 (2025)) rather than vibrational excitations as traditionally interpreted. In this context, it is important to identify possible low-lying vibrational excitations and to characterize the excitation energy at which they emerge. Focusing on two typical examples, $^{166}$Er and $^{162}$Dy, vibrational states are indeed identified above the $\gamma$ band using an extended version of the so-called T-plot. The phenomenon of shape coexistence is also shown to produce low-lying states below such vibrational band heads. These results suggest novel and rich structures in heavy deformed nuclei. While experimental counterparts are seen for some of such states, others are predictions opening doors to future dedicated experiments.

Evidence for parton energy loss in oxygen$-$oxygen collisions at $\mathbf{\sqrt{s_{\rm NN}}=5.36}$ TeV

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.19967v2 Announce Type: replace Abstract: Ultra-relativistic heavy-ion collisions create a hot and dense medium of deconfined quarks and gluons, the quark$-$gluon plasma (QGP), in which parton energy loss ("jet quenching") is a key probe of hot medium properties. While parton energy loss has been firmly established in large systems such as Pb$-$Pb and Au$-$Au collisions, no unambiguous direct evidence exists in smaller systems such as high-multiplicity p$-$Pb and pp collisions. To probe the onset of parton energy loss at intermediate system size, measurements of neutral-pion production are presented in this Letter for oxygen$-$oxygen (OO) and proton$-$oxygen (pO) collisions recorded with the ALICE detector in July 2025, relative to a pp baseline. The nuclear modification factor $R_{\rm OO}$ is suppressed relative to unity with a transverse-momentum dependence similar to that observed in Pb$-$Pb collisions, consistent with a previous CMS measurement in OO collisions with charged particles. As $R_{\rm OO}$ contains contributions from both cold and hot nuclear matter effects, $R_{\rm pO}$ is also presented in order to constrain cold nuclear matter (CNM) contributions. $R_{\rm pO}$ is found to be compatible with unity, indicating that CNM effects alone cannot account for the suppression observed in $R_{\rm OO}$. Final-state effects are isolated using the measured double ratio $R_{\rm OO} \left/ R_{\rm pO}^2 \right.$, which largely cancels CNM contributions and exhibits a significant suppression relative to expectations without energy loss at a 4.9$\sigma$ level. Theoretical models incorporating parton energy loss via different mechanisms predict a significant suppression of the $R_{\rm OO} \left/ R_{\rm pO}^2 \right.$ relative to unity, consistent with the data. These findings establish parton energy loss in OO collisions, extending experimental evidence for jet quenching to the smallest nuclear system studied to date.

First direct measurement of $^{48}$Ca single $\beta$-decay Q value with the TITAN Penning trap

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.03146v2 Announce Type: replace Abstract: Neutrinoless double $\beta$-decay (0$\nu\beta\beta$), if observed, would provide unequivocal evidence of physics beyond the Standard Model. $^{48}$Ca is an interesting candidate system to study because it has the largest Q value among all 2$\beta$ transitions and is also unstable against single $\beta$-decay. The observation of both $\beta$ and 2$\beta$-decay in the same isotope would provide a unique opportunity to benchmark theoretical calculations of $\beta$ and 2$\beta$-decay matrix elements and could provide insight on the quenching of the axial vector coupling constant, g$_A$. We performed a precise measurement of the $^{48}$Ca $\beta$-decay Q value using the TITAN Penning trap mass spectrometer at the TRIUMF facility. This was achieved through cyclotron frequency ratio measurements of $^{48}$Ca$^{+}$/$^{48}$Sc$^{+}$ and $^{48}$Sc$^{+}$/$^{48}$Ti$^{+}$ using the Time-of-Flight Ion Cyclotron Resonance technique. The $^{48}$Ca $\beta$-decay Q value was determined to be 279.14(50) keV, a factor of 10 more precise than the previous value given in the 2020 Atomic Mass Evaluation [Chin. Phys. C 45, 030003 (2021)]. This Q value was used to determine the $^{48}$Ca $\beta$-decay partial half-life, with the result $T_{1/2}^{\beta}$ = 5.09(5) x 10$^{20}$ ($g_{A}^{-2}$) y. Our $^{48}$Ca $\beta$-decay half-life was determined to a precision of 1%, a factor of 30 improvement compared to calculations with the previous Q value. Our result is marginally closer to the experimental lower limit $T_{1/2}^{\beta}$ > 1.1 x 10$^{20}$ y, but still a factor 5 longer. It is also a factor of 10 longer than the observed 2$\nu\beta\beta$ decay mode with $T_{1/2}^{2\nu\beta\beta} = 5.96^{+1.39}_{-1.08}$ x 10$^{19}$ y. Hence, it could be possible to observe $^{48}$Ca $\beta$-decay in future experiments, strengthening the potential importance of $^{48}$Ca to benchmark nuclear structure and 2$\beta$-decay studies.

Hofstadter-Herman Visualization as a Diagnostic Tool for Systematic Effects in Electromagnetic Form Factor Extractions

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2511.12007v3 Announce Type: replace Abstract: The internal charge and magnetization distributions of the proton are characterized by electromagnetic form factors GE and GM. They are experimentally extracted via Rosenbluth separation, which measures the elastic scattering of electrons and protons at multiple beam energies and angles at fixed momentum transfer Q2. Conventionally, form factor values are obtained by plotting reduced cross sections against the virtual photon polarization parameter epsilon and then extracting the slope and intercept of the best fit lines. An alternative visualization method, proposed by Hofstadter and Herman in 1960, plots GM2 vs. GE2 curves instead. The best fit values of GE2 and GM2 are immediately visible from the intersection region of the curves and their uncertainty bands. In this work, we apply both conventional and Hofstadter-Herman visualizations to classic 1994 SLAC elastic scattering data. We demonstrate that the Hofstadter-Herman method reveals previously obscured regions of form factor parameter space and highlights subtle experimental discrepancies among data sets. Our results motivate adopting this visualization method as a routine diagnostic cross-check at the Electron-Ion Collider and elsewhere to flag normalization shifts and related adjustments before they enter global fits.

Scaling Properties of the $\Delta\gamma$ Correlator: Constraints on Background and CME-Sensitive Charge Separation in Heavy-Ion Collisions

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2206.05773v3 Announce Type: replace Abstract: The scaling properties of the $\Delta\gamma$ correlator, guided by calculations from the Anomalous Viscous Fluid Dynamics (AVFD) model, are used to investigate charge separation in $p$+Au, $d$+Au, Ru+Ru, Zr+Zr, and Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$~GeV, and in $p$+Pb and Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ and $2.76$~TeV. The ratio $\Delta\gamma/v_2$, where $v_2$ is the elliptic-flow coefficient, exhibits a common approximate $1/N_{\rm ch}$ scaling behavior for $p$+Au, $d$+Au, $p$+Pb, and Pb+Pb collisions, establishing a common multiplicity-dilution baseline for background-driven charge correlations. In contrast, Ru+Ru, Zr+Zr, and Au+Au collisions show significant deviations from this scaling trend. These violations are qualitatively similar to those obtained in AVFD calculations with an input chiral magnetic effect (CME) signal and point to an additional charge-separation component beyond that expected from the observed background scaling. Quantitative estimates indicate that, in mid-central collisions, the corresponding CME-sensitive fraction of the measured $\Delta\gamma/v_2$ is approximately 27\% for Au+Au collisions and roughly a factor of two smaller for Ru+Ru and Zr+Zr collisions, which exhibit similar magnitudes within uncertainties. The extracted magnitudes imply an expected Ru+Ru--Zr+Zr signal difference of only $\sim1.3\%$, suggesting limited sensitivity of the $\Delta\gamma$ correlator to the small difference expected between the isobar signals.

Quantification of the Flavor Diagonal Hadronic CP Violation

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.23580v1 Announce Type: cross Abstract: The flavor diagonal CP violation of elementary particle physics contributes to the atomic, nuclear, and nucleon electric dipole moments (EDMs), T-violating neutron optics, and to the angular correlations of beta decay. In this contribution, we review the basics and the importance of CP violation in the search for new physics beyond the standard model, the recent progress in the quantification of the hadron level CP violation contributing to the aforementioned observables, and finally the current attempt to solve the strong CP problem without additional interactions and fields.

Ultra-Peripheral Collisions as a Nuclear-Structure Interferometer with Interpretable Multitask Deep Learning

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.23353v1 Announce Type: cross Abstract: Precise knowledge of nuclear structure is essential across fundamental physics, yet probing these structures is notoriously difficult. To address this challenge, ultra-peripheral collisions (UPCs) provide a femtoscopic tomography for imaging the atomic nucleus. UPCs offer a pristine electromagnetic pathway: coherent vector-meson photoproduction generates patterns of diffraction and two-source interference that directly encode the nuclear spatial density. Turning these patterns into quantitative constraints is, however, a challenging inverse problem, complicated by correlated sensitivities to deformation and neutron skin, phase smearing, and experimental backgrounds. Here we introduce an interpretable Multitask deep-learning framework that maps transverse momentum distributions to multiple nuclear-structure indicators simultaneously and identifies the kinematic regions driving each inference. We demonstrate the approach with coherent $J/\psi$ photoproduction in $^{96}_{40}\text{Zr} + ^{96}_{40}\text{Zr}$ collisions, showing that the learned features separate diffraction-dominated and interference-dominated information and provide analysis-ready observables for future high-luminosity data.

Exploring Pion-Induced High-Momentum Components in Nuclei via $(p,p'\pi)$ Reactions

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.23067v1 Announce Type: cross Abstract: Pion exchange plays a fundamental role in nuclear structure and is responsible for tensor correlations and high-momentum components in nuclei. The $(p,p'\pi)$ reaction provides a unique opportunity to investigate pion dynamics under large-momentum-transfer conditions. Its three-body kinematics allows large momentum transfer to be achieved while keeping the excitation energy of the residual nucleus low. We investigate the kinematical properties of the $^{12}\mathrm{C}(p,p'\pi^+)^{12}\mathrm{B}$ reaction using Lorentz-invariant three-body phase-space calculations. The calculations were performed for a 392-MeV proton beam assuming a constant transition amplitude. The resulting momentum-transfer map and phase-space distribution identify experimentally accessible regions of large momentum transfer and provide guidance for optimizing a double-arm spectrometer experiment at RCNP. The present study establishes a model-independent kinematical foundation for future investigations of pion-induced correlations, high-momentum components, and pion dynamics in nuclei.

Full Configuration Interaction Quantum Monte Carlo for Accurate $\textit{Ab Initio}$ Nuclear Structure Calculations

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.22341v1 Announce Type: cross Abstract: We introduce novel full configuration interaction quantum Monte Carlo (FCIQMC) as an accurate many-body solver for $\textit{ab initio}$ nuclear structure calculations. This stochastic approach directly samples the exact wave function in the full configuration space, enabling high-fidelity treatment of high-order many-body correlations in strongly interacting nuclear systems. Using interactions from chiral effective field theory, we have computed ground-state energies and charge radii of $^4$He, $^8$Be, $^{12}$C and $^{16}$O with sub-percent-level many-body uncertainties. These results establish FCIQMC as a stochastic full-configuration-space solver capable of treating systems beyond the reach of the conventional no-core shell model, and as an accurate benchmark for truncated many-body expansion methods.

Quantum noninvasive three-component beam-spin polarimetry in the Hadron Storage Ring of the Electron-Ion Collider

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.22265v1 Announce Type: cross Abstract: We propose a noninvasive SQUID-based polarimeter for the polarized proton beam in the Electron-Ion Collider (EIC) Hadron Storage Ring (HSR), exploiting the collective magnetic dipole moment of the bunches rather than scattering. The six-snake HSR lattice has synchronous-particle spin tune $\nu_s = 1/2$, placing the in-plane spin-precession signal at half the revolution frequency ($\sim$39 kHz), in the DC SQUID band. Three pickup channels (cosine-$\theta$ and sine-$\theta$ saddle loops for the transverse components, a coaxial axial gradiometer for the longitudinal one) reconstruct the full polarization vector $(P_x, P_y, P_z)$ in two complementary modes. Static mode, the default for continuous noninvasive monitoring, reads all three components: $P_y$ at the revolution frequency and the residual in-plane components at $\nu_s f_\mathrm{rev}$, bunch by bunch over an hours-long fill, including $P_z$, inaccessible to single-spin scattering polarimetry by parity conservation. Dynamic mode gives a precise polarization-magnitude measurement: a longitudinal kicker tips a small fraction of the polarization into the horizontal (ring) plane to produce a free-induction-decay (FID) signal, and many phase-locked tip-$\pi$-echo-restore cycles are summed coherently via a matched filter across all bunches, with $\mathcal{O}(\alpha^2/\pi^2) \sim 10^{-4}$ loss per cycle, negligible over a full $\delta P/P = 1\%$ measurement. For tipping angle $\alpha = 30$ mrad, polarization $P = 0.7$, and effective rms spin-tune spread $\sigma_{\nu_s}^\mathrm{eff} = 10^{-3}$ (coherence time $\sim$2 ms), the integration time to reach $\delta P/P = 1\%$ is about 18 s at injection and 5 min at flattop. The architecture extends to deuteron and $^3$He beams via species-specific spin-magnetic factors, with applications to storage-ring EDM searches.

Microscopic mechanism of the Fayans pairing for the enhancement of charge radii

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.21491v1 Announce Type: cross Abstract: The Fayans energy density functional (EDF), and in particular its pairing sector, have been claimed to be able to reproduce the experimental data of charge radii in many instances. A particularly intriguing case is that of the $ \mathrm{Ca} $ isotopes between $ A = 40 $ and $ 48 $, where charge radii exhibit a "bell shape". In our work, we examine the microscopic origin of this behaviour. We prepare in total $ 25 $ paramerizations of the Fayans-like pairing interaction, that are equivalent in fulfilling the same criteria for the reproduction of empirical pairing gaps. We find that both the density and the density-gradient dependence of the pairing interaction are important to reproduce the well-known enhancement of charge radii in the open-shell nuclei, leading to the "bell shape" behaviour of $ \mathrm{Ca} $ isotopes. In particular, this originates from the repulsive nature of the rearrangement potential, and cannot simply be mocked up by a refit of the pairing strength. At the same time, we notice some drawbacks of the Fayans standard EDFs, that may call for investigating a more general form of it.

Characterization of GaN:Si and ZnO:Ga for position-resolved fast timing applications

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.21299v1 Announce Type: cross Abstract: We present the characterization of two fast, crystalline inorganic scintillators, silicon-doped gallium nitride (GaN:Si) and gallium-doped zinc oxide (ZnO:Ga), and compare their performance with cerium-doped yttrium aluminium perovskite (YAP:Ce) for in-vacuum alpha-detection applications that require high-performance timing, position, and energy resolution, such as 3D elemental mapping, medical imaging, and homeland security applications. In this paper, we propose ZnO:Ga and GaN:Si as high-performance drop-in replacements for the alpha detector in Associated Particle Imaging (API) systems. However, the results reported here also have wide applicability. Prior work has reported on polycrystalline forms of ZnO:Ga, which suffer from self-absorption. To our knowledge, GaN:Si has not been proposed to be used in API systems. We present room-temperature scintillation time constants obtained via X-ray-induced time-correlated single-photon counting for both proposed materials. They both exhibit exceedingly fast rise times of 1000ph/MeV with resolved alpha-peaks. Single-crystal ZnO:Ga and single-crystal GaN:Si yield single-component decays of 805ps and 32ps, respectively. Using a plastic scintillator reference setup, coincidence timing resolution (CTR) and detector timing resolution (DTR) measurements demonstrate a >3x improvement in timing resolution compared to traditional YAP:Ce. GaN:Si and ZnO:Ga exhibit (35(9))ps and (49(5))ps DTR, respectively, compared to(144(2))ps for conventional, single-crystal YAP:Ce. Finally, we evaluate their position resolution in an experimental setup designed for API and measure better than 0.2mm for YAP:Ce and approximately 1mm for GaN:Si. We obtain a position resolution of 0.3mm for ZnO:Ga from simulations. We also present alpha-induced ionoluminescence emission spectra that reveal direct, red-shifted near-bandgap emission.

Single Particle Excitations, Band Structures and Octupole Correlation in $^{65}$Zn

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.23169v1 Announce Type: new Abstract: The excitation scheme of the $^{65}$Zn ($Z = 30, N = 35$) nucleus has been probed following its population in the $^{63}$Cu($\alpha$,pn) reaction at E$_{beam}$ = 30 MeV and using an array of Compton suppressed HPGe clovers as the detection system. This work has identified several new transitions of the nucleus and have modified the placements of some of the previously known ones. The multipolarities and the electric/ magnetic nature of the observed $\gamma$-ray rays have been measured, using the conventional methodologies. The spin-parity assignments for the levels have consequently been made; some of the spin-parities are new while others are either validation of the existing values or are modified results based on the present analysis. The experimental level scheme exhibits collective as well as single particle structures. The measured level energies have been compared with those calculated in the framework of the large basis shell model using a model space of $p_{3/2}, f_{5/2}, p_{1/2}, g_{9/2}$ orbitals and two different interactions. The collective excitations of the nucleus were probed through the properties of its band structures and through the calculations of the Total Routhian Surface (TRS) for the associated deformations/ shapes. The results of this study brings out the essential features of evolving structural characteristics and developing collectivity with increasing number of nucleons outside a doubly-magic core and with their occupancy of deformation driving high-$j$ orbitals.

Development of a Neural Network-Based Background Suppression Technique for $\Sigma N$ Cusp Spectroscopy at J-PARC

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.22750v1 Announce Type: new Abstract: A clear spectral enhancement, known as the ``$\Sigma N$ cusp'', has been observed near the $\Sigma N$ threshold in the $d(K^-, \pi^-)$ reaction. To understand the dynamical origin of this enhancement, the J-PARC E90 experiment aims to investigate the missing-mass spectrum with an unprecedented resolution of 0.4 MeV ($\sigma$). In this experiment, a Hyperon Time Projection Chamber (HypTPC) is utilized to detect charged decay products and suppress severe contamination from quasi-free (QF) background processes. While a conventional track multiplicity condition of three (Mt=3) effectively suppresses these QF events, it restricts the signal statistics to approximately 17\% and introduces a mass-dependent acceptance bias that distorts the spectrum. In contrast, events with a track multiplicity of two (Mt=2) offer roughly double the statistical power ($\sim$39\%) with minimal mass dependence, but they suffer from heavy background contamination. To fully exploit the Mt=2 events, we developed an innovative background suppression technique based on a neural network. By constructing a binary classification model using the HypTPC track topology and energy loss ($dE/dx$) as input features, we successfully discriminated the signal from QF backgrounds. This machine learning approach achieves a signal-to-noise ratio comparable to the strict Mt=3 condition while preserving the integrity of the spectral shape. By combining this independent ML-selected Mt=2 sample with the conventional Mt=3 sample, the total usable statistics are effectively doubled compared to traditional methods, significantly enhancing the sensitivity for determining the $\Sigma N$ cusp parameters.

Hyper-Nuclei $^4_{\Lambda}\hbox{He}$ Production in $\sqrt{s_{\rm{NN}}}$ = 3 GeV Au+Au collisions at RHIC

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.22457v1 Announce Type: new Abstract: The STAR experiment reports the first measurement of the $^4_{\Lambda}\hbox{He}$ hyper-nuclei yield as a function of rapidity and transverse momentum in 0-50% central Au+Au collisions at $\sqrt{s_{\rm{NN}}} =$ 3 GeV. The $^4_{\Lambda}\hbox{He}$ is reconstructed through its three-body decay channel, $^4_{\Lambda}\rm{He} \rightarrow {}^{3}\rm{He} + \rm{p} + \pi^-$, with a statistical significance of about 9.5 standard deviations. We find that the yield of $^4_{\Lambda}\hbox{He}$ as a function of rapidity is consistent with that of $^4_{\Lambda}\hbox{H}$, and the rapidity-dependent yield ratio of $^4_{\Lambda}\hbox{He}$/$^4_{\Lambda}\hbox{H}$ is consistent with that of $^3$He/t. All the measurements, as well as the transverse-momentum spectra, can be reasonably described by the JAM with a coalescence afterburner, suggesting a coalescence-based formation scenario for hyper-nuclei at this energy. The canonical thermal model reproduces the observed yield ratios but overpredicts the absolute hyper-nuclei yields.

Heavy rigid body with a gyroscope in $\mathbb R^n$

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2601.03965v2 Announce Type: replace-cross Abstract: Starting from the following multidimensional integrable generalizations of the heavy rigid body systems: the Euler top, the Lagrange top, the Lagrange bitop, and the totally symmetric case, we add to each of them a gyroscope. For each of the newly constructed systems, we provide a polynomial matrix Lax representation and prove Liouville integrability.

Isoperiodic deformations of Abelian differentials of the second kind over elliptic curves and the Boussinesq equation

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2512.06162v2 Announce Type: replace-cross Abstract: We study deformations of a genus one Riemann surface and of a second order Abelian differential on the surface which preserve the periods of the differential with respect to a chosen canonical homology basis of the surface. We call these deformations isoperiodic. We derive a second order ordinary differential equation with rational coefficients governing the variations of the position of the unique pole of the differential under the isoperiodic deformations. The obtained equation depends on the order of the pole of the differential. We characterize the solutions of the obtained ordinary differential equations that correspond to the isoperiodic deformations. We apply these results to the theory of genus one solutions to the Boussinesq equation.

Normal sub-Riemannian geodesics related to filtrations of Lie algebras

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2512.05553v2 Announce Type: replace-cross Abstract: There is a natural way to construct sub-Riemannian structures that depend on $n$ parameters on compact Lie groups. These structures are related to the filtrations of Lie subalgebras $\mathfrak g_0 < \mathfrak g_1 < \mathfrak g_2 < \dots < \mathfrak g_{n-1}<\mathfrak g_n=\mathfrak g=Lie(G)$. In the case where $n=1$, the explicit solution for normal sub-Riemannian geodesics was provided by Agrachev, Brockett, and Jurjdevic. We extend their solution to apply to general chains of Lie subgroups. Additionally, we describe normal geodesic lines of the induced sub-Riemannian structures on homogeneous spaces $G/K$, where $\mathfrak g_0=Lie(K)$.

A Martingale-Free Introduction to Conditional Gaussian Nonlinear Systems

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2410.24056v3 Announce Type: replace-cross Abstract: The conditional Gaussian nonlinear system (CGNS) is a broad class of nonlinear stochastic dynamical systems. Given the trajectories for a subset of state variables, the remaining follow a Gaussian distribution. Despite the conditionally linear structure, the CGNS exhibits strong nonlinearity, thus capturing many non-Gaussian characteristics observed in nature through its joint and marginal distributions. Desirably, it enjoys closed analytic formulae for the time evolution of its conditional Gaussian statistics, which facilitate the study of data assimilation and other related topics. In this paper, we develop a martingale-free approach to improve the understanding of CGNSs. This methodology provides a tractable approach to proving the time evolution of the conditional statistics by deriving results through time discretization schemes, with the continuous-time regime obtained via a formal limiting process as the discretization time-step vanishes. This discretized approach further allows for developing analytic formulae for optimal posterior sampling of unobserved state variables with correlated noise. These tools are particularly valuable for studying extreme events and intermittency and apply to high-dimensional systems. Moreover, the approach improves the understanding of different sampling methods in characterizing uncertainty. The effectiveness of the framework is demonstrated through a physics-constrained, triad-interaction climate model with cubic nonlinearity and state-dependent cross-interacting noise.

Painlev\'e-type asymptotics for the defocusing Manakov system with nonzero boundary conditions

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2603.18430v2 Announce Type: replace Abstract: We investigate the long-time asymptotic behavior of a class of solutions to the defocusing Manakov system under nonzero boundary conditions. These solutions are characterized by a $3 \times 3$ matrix Riemann Hilbert problem. We find that they exhibit interesting asymptotic behavior within a narrow transition zone in the $x$-$t$ plane. We determine the leading-order asymptotic term and the error bound in this region, and we demonstrate that the leading term can be expressed in terms of the Hastings-McLeod solution of the Painlev\'e II equation. The proof is rigorously established by applying the Deift-Zhou nonlinear steepest descent method to the associated Riemann Hilbert problem.

Additional symmetries of the KP-mKP hierarchy and Virasoro constraints to the Burgers-KdV hierarchy

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2603.01354v2 Announce Type: replace Abstract: A KP-mKP hierarchy was introduced recently via pseudo-differential operators containing two derivations. In this paper, for the KP-mKP hierarchy we derive a class of (differential) Fay identities and construct a series of additional symmetries. Moreover, the additional symmetries are represented as certain linear actions on the tau functions of the hierarchy, with the help of the Adler-Shiota-van Moerbeke formula. As an application, we reprove the Virasoro constraints to the tau functions of the Burgers-KdV hierarchy, and such results are generalized to its higher order extensions regarded as reductions of the KP-mKP hierarchy.

Large-time asymptotics for the defocusing Manakov system on a nonzero background

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2512.21841v2 Announce Type: replace Abstract: The Manakov system is a two-component nonlinear Schr\"odinger equation. In this paper, we derive a long-time asymptotic formula for the solution of the defocusing Manakov system with nonzero boundary conditions and provide a detailed proof. We first formulate the inverse problem as a $3\times3$ matrix Riemann--Hilbert problem. We then carry out the Deift--Zhou steepest descent analysis for this Riemann--Hilbert problem and obtain the long-time asymptotics in the space-time soliton region. In this region, the leading order of the solution takes the form of a modulated multisoliton. Apart from the error term, we also discover that the defocusing Manakov system has a dispersive correction term of order $t^{-1/2}$, but this term does not exist in the scalar case, and we provide the explicit expression for this dispersion term.

Bihamiltonian structure of the $(n,1)$-type rational reductions of the 2D-Toda hierarchy

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.23167v1 Announce Type: new Abstract: We derive a local bihamiltonian structure for the rational reduction of the 2D-Toda hierarchy (RR2T) of $(n,1)$-type by direct computations, and construct an $(n+1)$-dimensional semisimple generalized Frobenius manifold with non-flat unity whose Principal Hierarchy contains its dispersionless flows.

Exact Harmonic Dimensional Reduction and Conformal Lifting for Multicomponent $(3+1)$ Nonlinear Schr\"odinger Systems

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.22808v1 Announce Type: new Abstract: A harmonic dimensional reduction framework is developed for $(3+1)\mathrm{D}$ systems of coupled nonlinear Schr\"odinger-type equations with stationary transverse trapping potentials. The central result is a lifting lemma: if the transverse phase functions are harmonic and the trapping potential exactly cancels the squared phase gradient, the full $(3+1)\mathrm{D}$ system reduces identically to a closed $(1+1)\mathrm{D}$ integrable hierarchy, and every solution of the reduced system lifts to an exact solution of the original multidimensional model. The framework is applied to four systems. For the scalar Gross--Pitaevskii equation, Kuznetsov--Ma breathers are embedded in $(3+1)\mathrm{D}$ geometries carrying vortex lattices with finite, non-singular density at the cores. For the two-component Manakov system, the phase-inversion ansatz yields exact vector solutions with vanishing mass current and non-trivial transverse spin current modulated by the longitudinal breather. For the three-component spinor $F=1$ Bose--Einstein condensate, a symmetric Kuznetsov--Ma breather and a spin-exchange rogue wave are constructed, the latter exhibiting transient density amplification by a factor of nine in the $m_F=0$ channel. For the Maxwell--Bloch system, self-induced transparency solitons, two-soliton elastic collisions, and Kuznetsov--Ma breathers are lifted to full $(3+1)\mathrm{D}$ geometry, with population inversion remaining transversely uniform despite arbitrary phase winding in the cross-section.

Unified theory of oscillons and modes

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.22680v1 Announce Type: cross Abstract: We show that an oscillon can be understood as a localized discrete resonant (non-normalizable) mode. Specifically, oscillon in the vacuum arises from the threshold mode, which because of nonlinearity gets localized. Following this idea, we find {\it wobblerons} - nonlinear excitations of kinks, that is, oscillons-kink bound state. Now, the oscillon can also originate in an antibound mode, i.e., a discrete, positive energy but non-normalizable mode.

Geometric Structures of Pseudo-Sonic Curves in Self-Similar Solutions of the Euler Equations for Potential Flow

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.21793v1 Announce Type: cross Abstract: We are concerned with the geometric structures of pseudo-sonic curves in two-dimensional self-similar solutions for the Euler equations for potential flow, allowing for non-uniform supersonic states. Mathematically, the governing second-order potential flow equation is of mixed hyperbolic-elliptic type, with degeneracy occurring along the pseudo-sonic curve. In this paper, we develop rigorous analytical approaches to analyze the geometric structures of pseudo-sonic curves in such self-similar solutions. We first show that the pseudo-sonic curve is necessarily a circle if the pseudo-velocity at each point is a normal to the curve. We then analyze the general case in which the pseudo-velocity on the pseudo-sonic point is not a normal to the curve, and study the geometric properties of streamlines in a neighborhood of the pseudo-sonic curve. Next, we establish two theorems that provide sufficient conditions ensuring that the pseudo-velocity at a pseudo-sonic point is normal to the curve, under natural assumptions on the local behavior of the solution. These results yield a precise characterization of the geometry of pseudo-sonic curves. Finally, we apply the developed theory to the shock reflection-diffraction problem with non-uniform incoming flow. We prove that the pseudo-sonic curve must be an arc if the solution is a $C^2$-small perturbation, either in the pseudo-supersonic or pseudo-subsonic region, of a solution with uniform incoming flow. In particular, the density and velocity must be constant, corresponding to the radius and the center of the pseudo-sonic arc, respectively. Moreover, we prove that the solution is $C^{2,\alpha}$-regular in the pseudo-subsonic region up to the sonic arc (except at point $P_1$). The techniques and ideas developed in this paper are expected to be applicable to other nonlinear problems involving similar mixed-type degeneracies.

Asymptotic limits of constrained instantons

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.21561v1 Announce Type: cross Abstract: We revisit the topic of false vacuum decay in field theory. We focus on a toy model of a real massive scalar field with an unstable quartic potential. This model has a false vacuum, and decay out of the false vacuum can be described via the method of constrained instantons, which work by introducing a constraint on the path integral. We identify and develop three different asymptotic limits which enable analytic construction of approximate {constrained} solutions. The first, in which the constrained solution is small compared to the inverse mass of the scalar field, is an application of the perturbative methods of Affleck, although we re-derive the main results and identify several terms which were previously neglected. Second, for very large constrained solutions we adapt the thin-wall approximation of Coleman. However, we find that the large instanton limit does not always exist. In this case we identify another useful limit, in which the Lagrange multiplier used to implement the constraint is large. In this limit, the solution's scaling with the parameters may be found via dimensional analysis and an exact solution is obtained with a single numerical computation.

Financial Frequency Combs

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.23142v1 Announce Type: new Abstract: Frequency combs are discrete, equally spaced, phase-coherent spectral lines that emerge from nonlinear mode coupling in physical systems. We show that the incommensurate fractional-order financial model of Huang, Li, Ma, and Chen, whose Caputo derivatives encode macroeconomic long-range memory, generates an analogous structure in its steady-state spectrum. The comb appears only over specific values and ranges of the saving amount $a$, the investment cost $b$, and the demand elasticity $c$, outside which the spectral lines lose their equal spacing. It persists across extended parameter regimes and stays invariant to perturbations in the initial interest rate $x_0$ and investment demand $y_0$, while distinct spectral regimes appear at different initial price levels $z_0$. The comb is generated only when the fractional-order exponents $q_1$, $q_2$, and $q_3$ associated with interest rate, investment demand, and price index are above the critical threshold values. At even higher values of these exponents, the frequency comb transitions into chaos. These findings show that the long-run cyclic structure of a memory-bearing financial economy organises into a discrete, deterministic spectral fingerprint rather than a stochastic continuum.

Dimensional reduction for optical beams with thermal nonlocal nonlinearity

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.22553v1 Announce Type: new Abstract: Nonlocal optical nonlinearities arising from the thermorefractive effect provide a long-range material response determined by heat diffusion and absorption. In graded-index media, this nonlocality fundamentally alters modal interactions, yet its accurate modeling remains computationally demanding when starting from the full spatial nonlinear Schr\"odinger equation. In this work, inspired by the nonpolynomial Schr\"odinger equation (NPSE) framework, we extend the dimensional reduction techniques to incorporate thermally mediated nonlocal nonlinearities. By coupling the optical field to an equation for the temperature-induced refractive index change, and employing a variational ansatz based on Laguerre--Gauss modes of the annular kind, of arbitrary azimuthal order, we derive explicit analytic expressions for the variational equations. The resulting effective model captures the dependence of the nonlinear interaction on mode order and degree of nonlocality, providing a tractable reduced description of the dynamics in thermal nonlocal media.

Controllable excitation of vector Akhmediev breather patterns

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.21301v1 Announce Type: new Abstract: In the focusing Manakov system, multiple modulation instability (MI) branches coexist on the same plane wave background, so the usual weak periodic modulation cannot selectively excite a single vector Akhmediev breather (AB). Here we propose an eigenvector-based initial perturbation scheme that constructs the initial condition as a plane wave plus Fourier modes whose coefficients follow the perturbation eigenvector of a selected MI branch, enabling controllable high-fidelity excitation of desired vector ABs. Numerical simulations show near-100\% fidelity with the exact AB solution. The underlying mechanism is eigenvector-controlled mode selection. The initial seeding of the target MI branch through the chosen eigenvector, together with the non-Hermitian coupling inherent in the linearized MI dynamics, ensures that the targeted unstable mode dominates the early linear stage and thereby dictates the breather type. This eigenvector-based control succeeds in gain-balanced regimes and when the targeted branch has a sufficient gain advantage. The proposed method provides a simple and robust framework for controllable generation of vector ABs over a broad parameter range, highlighting the key role of eigenvector selectivity in multi-component nonlinear systems.

PyTorchFire: A GPU-Accelerated Wildfire Simulator with Differentiable Cellular Automata

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2502.18738v2 Announce Type: replace-cross Abstract: Accurate and rapid prediction of wildfire trends is crucial for effective management and mitigation. However, the stochastic nature of fire propagation poses significant challenges in developing reliable simulators. In this paper, we introduce PyTorchFire, an open-access, PyTorch-based software that leverages GPU acceleration. With our redesigned differentiable wildfire Cellular Automata (CA) model, we achieve millisecond-level computational efficiency, significantly outperforming traditional CPU-based wildfire simulators on real-world-scale fires at high resolution. Real-time parameter calibration is made possible through gradient descent on our model, aligning simulations closely with observed wildfire behavior both temporally and spatially, thereby enhancing the realism of the simulations. Our PyTorchFire simulator, combined with real-world environmental data, demonstrates superior generalizability compared to supervised learning surrogate models. Its ability to predict and calibrate wildfire behavior in real-time ensures accuracy, stability, and efficiency. PyTorchFire has the potential to revolutionize wildfire simulation, serving as a powerful tool for wildfire prediction and management.

It's Much Easier for Neural Networks to learn Game of Life Dynamics with the Right Activation Function: Polynomial Kolmogorov-Arnold Networks

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.23587v1 Announce Type: cross Abstract: Previous work has found a gap between the scale of neural networks that reliably learn Conway's Game of Life, and minimal networks capable of representing the classic cellular automaton with hard-coded parameter values. Viewing neural network learning as a search process suggests a dependence on networks large enough to contain sub-networks with lucky initializations (sometimes known as 'winning tickets') that actually learn the task. In this work, we reorient our perspective from discovering Life rules as a search problem back to a learning problem, and reason that with fitting inductive biases, the problem should be much more amenable to minimal networks. We find that network variants with several alternative activation functions meaningfully outperform the default choice of Rectified Linear Units, and in particular, that a 2nd degree polynomial activation function consistently learns Life dynamics with or without the benefit of learning neural weights. Our results provide an informative demonstration of the benefits of matching learning to the task at hand and challenge the easy default choice of scale for all problems. In particular, we advocate for the use of cellular automata as simple test domains for developing strategies that can benefit machine learning for science, physics-based deep learning, and interpretable machine learning.

Elementary derivation of the dissipation-coherence bound for stochastic oscillators

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2510.14101v3 Announce Type: replace-cross Abstract: The dissipation-coherence bound is a conjectured tradeoff between entropy production and the quality of stochastic oscillations. We show that this bound can be derived by combining the higher-order ``thermodynamic uncertainty relation'' with a simple condition on phase-current fluctuations. In one-dimensional cyclic systems, our proposed condition is shown to be equivalent to the dissipation-coherence bound itself. Our approach yields an elementary proof in the weak-noise Gaussian regime and extends naturally to some non-Gaussian systems, as we illustrate with a run-and-tumble particle. Finally, we contrast current-based and spectral formulations of the dissipation-coherence bound.

Data-driven geometric phase in biological locomotion

Tue, 23 Jun 2026 00:00:00 -0400

arXiv:2606.22440v1 Announce Type: cross Abstract: Geometric phase quantifies net locomotion in dissipative media via gauge theory, but linking this theoretical quantity to noisy, sparse, and weakly periodic biological shape data is challenging. We develop a theory-guided, data-driven Koopman autoencoder to recover the limit cycle embedded in imperfect cyclic data and extract shape gaits and geometric phase from sperm and nematode data. We introduce a geometric phase sensitivity function that quantifies responses to shape perturbations and reveals mechanical information using only gauge-theoretic structure, without assuming mechanical laws.

Optical Thermodynamics Beyond the Weak Nonlinearity Limit

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2602.13161v4 Announce Type: replace Abstract: Optical thermodynamics has recently emerged as a theoretical framework describing a Rayleigh-Jeans (RJ) modal power distribution of multimoded nonlinear photonic circuits. However, its applicability is constrained to systems exhibiting weak nonlinear mode-mode interactions. Here, by employing a Transfer Integral Operator, we circumvent this limitation and establish a steady-state interacting RJ modal distribution -- referred to as non-ideal RJ (NIRJ) -- with renormalized temperature and optical chemical potential. This also builds a natural bridge with earlier work on grand-canonical statistical-mechanical formulations of discrete nonlinear systems. The theory derives the optical analogue of the compressibility factor, which controls the transition from an ideal, non-interacting equation of state (EoS) to a van der Waals-like interacting EoS.

Probing flavor effects in the QCD parton shower using $\mathbf{{\rm D}^0}$-tagged jet angularities in proton$-$proton collisions at $\mathbf{ \sqrt{s} = 5.02}$ TeV

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2606.20028v1 Announce Type: new Abstract: The ALICE Collaboration presents the first measurements of ${\rm D}^0$-tagged jet angularities in proton$-$proton (pp) collisions at $\sqrt{s} = 5.02$ TeV. Jet angularities are powerful substructure observables that characterize the angular and momentum distributions of particles within jets via tunable weighting parameters. Varying the angular parameter in jet angularities allows for a systematic probe of the sensitivity to collinear and soft radiation, enabling the study of flavor-dependent fragmentation and hadronization through comparisons of jets initiated by different partons. This paper reports ${\rm D}^0$-tagged and inclusive (gluon-dominated) charged-particle jet angularities with a resolution parameter $R=0.4$ in the low jet transverse momentum range ($10 < p_{\rm T}^{\rm ch. \, jet} < 20$ GeV/$c$), where charm-quark mass effects are most significant. At low angular weight, which emphasizes collinear radiation, ${\rm D}^0$-tagged jets exhibit smaller angularity values than inclusive jets. This provides evidence for the radiation suppression from massive quarks -- a phenomenon known as the QCD dead-cone effect. As the angular weight increases, giving more emphasis to wide-angle radiation, the difference between ${\rm D}^0$-tagged and inclusive jet distributions decreases. This indicates that the modification is concentrated within the jet core rather than its edge. PYTHIA 8 simulations qualitatively reproduce both the angularity of ${\rm D}^0$-tagged and inclusive charged-particle jets, but reproduce the ${\rm D}^0$-tagged jet distributions better than those of inclusive jets, offering a powerful new constraint for models. These results provide insight into flavor-dependent fragmentation and establish an essential baseline for future studies of jet modifications in the quark-gluon plasma produced in heavy-ion collisions.

Modification of jet-energy flow in heavy-ion collisions

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2606.20061v1 Announce Type: new Abstract: The ALICE Collaboration presents the first measurements of the jet-energy flow ($\Delta p_{\rm T}$) observable in proton-proton and heavy-ion collisions. Jets are excellent probes for the quark$-$gluon plasma, a deconfined state of matter produced in heavy-ion collisions. The jet-energy flow observable characterizes the radial distribution of energy from the jet axis in an infrared and collinear-safe way and is sensitive to medium-induced parton-shower modifications. Inclusive charged jets are measured in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV for the transverse-momentum interval 60$-$80 GeV/$c$. For pp collisions at $\sqrt{s}=13$ TeV, measurements include the 40$-$60 and 60$-$80 GeV/$c$ intervals, where the latter serves as the reference for investigating medium-induced modifications. Results show that most parton energy is concentrated in the jet core, with a clear suppression of energy flow in heavy-ion collisions at larger radii (significance 3.5$-$4.5$\sigma$) indicating a narrowing of the energy flow. While all models -- PYTHIA 8, HERWIG, JEWEL, and JETSCAPE -- reproduce the pp results with only small deviations in the tails, the relative modification in Pb$-$Pb collisions is well described by JEWEL without recoil. Conversely, JEWEL with recoil (medium response) and JETSCAPE show significant deviations, exhibiting increasing or more constant trends with radius that are disfavored by the data.

Observation of centrality-dependent dijet transverse momentum imbalance in O+O and Ne+Ne collisions at $\sqrt{s_{NN}}$ = 5.36 TeV with the ATLAS detector

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2606.20463v1 Announce Type: new Abstract: The ATLAS experiment presents an observation of a centrality-dependent dijet transverse momentum imbalance in O+O and Ne+Ne collisions at a nucleon-nucleon center-of-mass energy of 5.36 TeV at the Large Hadron Collider. The measurement uses 8.0 nb$^{-1}$ of O+O and 1.0 nb$^{-1}$ of Ne+Ne data collected in 2025, together with 386 pb$^{-1}$ of \textit{pp} data at the same energy used as a reference. The dijet momentum balance is quantified using the ratio of the sub-leading jet transverse momentum to that of the leading jet, $x_J$. For dijets produced azimuthally back-to-back, the self-normalized $x_J$ distributions exhibit increasingly large deviations from the \textit{pp} reference as collisions become more central, corresponding to an increasing overlap of the colliding nuclei. The observed centrality dependence is consistent with medium-induced partonic energy loss in O+O and Ne+Ne collisions, demonstrating that such effects persist in collision systems considerably smaller than Pb+Pb and Xe+Xe. These results establish a new regime for investigating the path-length dependence of jet quenching and constrain the onset of quark-gluon plasma effects in small nuclear collision systems.

Azimuthal Anisotropy Scaling Functions for Identified Particle and Anti-Particle Species across Beam Energies: Insights into Baryon Junction Effects

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2410.22688v4 Announce Type: replace Abstract: Azimuthal anisotropy scaling functions are constructed from species-resolved anisotropy measurements in Pb+Pb ($\sqrt{s_{NN}}$=2.76, 5.02~TeV) and Au+Au ($\sqrt{s_{NN}}$=7.7--200~GeV) collisions to probe baryon transport and medium response at finite baryon chemical potential ($\mu_B$). Within this data-driven framework, meson and baryon anisotropies spanning the collective-flow and quenching regimes collapse onto common scaling curves, enabling quantitative separation of viscous attenuation, radial flow, and hadronic re-scattering. The attenuation scale $k_\beta$ exhibits a non-monotonic beam-energy dependence, coincident with the low-energy rise of hadronic re-scattering, consistent with a temperature-dependent specific shear viscosity featuring a near-minimum near the QCD critical region. A charge-odd baryon--antibaryon separation in the effective radial-flow response is negligible at LHC energies but grows toward lower $\sqrt{s_{NN}}$. This species-uniform, baryon-number-scaling separation across $p,\Lambda,\Xi,\Omega$, and $d$ disfavors a purely hadronic origin and supports junction-driven net-baryon transport at finite $\mu_B$, enhancing the experimental visibility of critical dynamics in finite, rapidly evolving systems. Together, these results establish species-resolved scaling functions as a compact and robust tool for constraining baryon stopping, medium opacity, and QGP transport properties.

Direct Measurement of the $^{212}\mathrm{Pb}$ and $^{214}\mathrm{Pb}$ $\beta$ Decay Branching Ratios with the XENONnT Experiment

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2606.17920v2 Announce Type: replace Abstract: We present precision measurements of $^{212}\mathrm{Pb}$ and $^{214}\mathrm{Pb}$ $\beta$ decay branching ratios using $^{220}\mathrm{Rn}$ and $^{222}\mathrm{Rn}$ calibration data from the XENONnT detector, a dual-phase liquid xenon time projection chamber. Characterizing these isotopes is critical, as they lead to significant low-energy backgrounds in rare-event searches. We report ground-state branching ratios of $(14.75 \pm 0.20(\mathrm{stat}) ^{+0.14}_{-0.40}(\mathrm{sys}))\%$ for $^{212}\mathrm{Pb}$ and $(9.8 \pm 0.3(\mathrm{stat}) ^{+0.8}_{-0.2}(\mathrm{sys}))\%$ for $^{214}\mathrm{Pb}$, providing the most precise direct measurements of these transitions to date. These results contribute to enhancing background modeling for dark matter and neutrino experiments, improving sensitivity to solar neutrinos and physics beyond the Standard Model.

New insights from the flavor dependence of quark transverse momentum distributions in the pion

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2509.25098v2 Announce Type: replace-cross Abstract: We update our previous extraction of transverse momentum distributions of unpolarized quarks in the pion by implementing a more comprehensive description of theoretical uncertainties and, for the first time, by exploring possible differences among quark flavors. We extract such distributions from all available data for unpolarized pion-nucleus Drell-Yan processes, where the cross section is differential in the transverse momentum of the final lepton pair. The cross section involves transverse momentum distributions in the nucleon, that we consistently take from our previous studies.

A relativistic mechanism for the enhanced isovector spin-orbit interaction suggested by parity-violating electron scattering experiments

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2511.15385v2 Announce Type: replace-cross Abstract: Recent high-precision parity-violating electron scattering (PVES) measurements on $^{208}$Pb (PREX-II) and $^{48}$Ca (CREX) reveal a tension in their simultaneous description within modern nuclear energy density functionals (EDFs). Analyses of these data suggest that an enhanced isovector spin-orbit interaction may help account for both measurements, but its relativistic origin in covariant density functional theory remains to be clarified. We show that, within the framework of a covariant density-dependent point-coupling EDF, an enhanced isovector tensor coupling can naturally induce such a strong isovector spin-orbit interaction. This mechanism provides a promising route toward a simultaneous description of the PREX-II and CREX results while preserving a reasonable description of finite nuclei and nuclear matter. PVES on $^{48}$Ca thus provides a sensitive probe of the covariant isovector tensor interaction.

Trace anomaly and interior curvature of neutron stars in energy-momentum squared gravity

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2606.20203v1 Announce Type: new Abstract: In energy-momentum squared gravity (EMSG), the spacetime inside a neutron star is sourced by effective thermodynamic variables that need not coincide with the physical fluid pressure and energy density. It is therefore an open question whether the trace anomaly of dense matter -- the QCD measure of how strongly conformal symmetry is broken -- still organizes interior profiles and curvature in the same way it does in general relativity (GR). We adopt a clear matter-geometry separation: the trace anomaly is computed from the fluid sector alone, while spacetime curvature scalars are built from the variables that actually source the modified Tolman-Oppenheimer-Volkoff equations. For five relativistic mean-field equations of state, the radial trace-anomaly profiles increase monotonically from core to surface in all accepted EMSG models, as in GR, but split systematically with the EMSG coupling strength; the splitting grows with stellar compactness. Despite this deformation, curvature invariants still fall onto organized bands when plotted against the trace anomaly, extending the GR thermodynamic-geometric correspondence. The Ricci contraction shows the tightest organization, whereas the Ricci scalar remains the most equation-of-state sensitive. EMSG effects are modest for observationally accessible stars but largest in stiff, ultracompact configurations, indicating that the trace anomaly remains a useful thermodynamic label for interior geometry even when gravity couples nonlinearly to matter.

Space-time regions of high baryon density and baryon stopping in heavy-ion collisions

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2602.22690v2 Announce Type: replace Abstract: Four-volumes ($V_4=$ spatial-3-volume$\times$lifetime) are calculated within the model of three-fluid dynamics (3FD) and compared with those of the the JET AA Microscopic Transport Model (JAM). The calculations are performed for central Au+Au collisions at energies $\sqrt{s_{NN}}=$ 3 -- 19.6 GeV. These $V_4$ indicate optimal collision-energy ranges for realizing macroscopic high baryon-density matter. It is found that the 3FD four-volumes noticeably exceed those in the JAM, which indicates a stronger baryon stopping in the 3FD model as compared to that JAM. It is argued that this difference in the baryon stopping correlates with stiffness of the EoS implemented in these models. Contrary to JAM, the four-volume, where a baryon density ($n_B$) exceeds three times the normal nuclear density ($n_0$), does not exhibit a maximum as a function of $\sqrt{s_{NN}}$. It decreases monotonically with increasing $\sqrt{s_{NN}}$, remaining at a fairly macroscopic level (i.e. $V_4\geq 5.5^4$ fm$^4$/c). For higher baryon densities, $V_4$ exhibits maxima in its dependence on $\sqrt{s_{NN}}$. The optimal energy range for densities $n_B/n_0>$ 4 is located at $\sqrt{s_{NN}}=$ 3.2 -- 8 GeV. Even for $n_B/n_0>$ 6, the four-volume remains quite macroscopic ($V_4\geq 4^4$ fm$^4$/c) at $\sqrt{s_{NN}}=$ 4.5 -- 9 GeV contrary to the JAM.

Relativistic corrections to exclusive photoproduction of Quarkonia near-threshold

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2506.18905v2 Announce Type: replace-cross Abstract: Non-relativistic QCD (NRQCD) is used to calculate the relativistic correction to the amplitude for exclusive photoproduction of vector Quarkonia in the near-threshold region within the generalized parton distribution (GPD) framework. The relativistic corrections are found to be large for $J/\psi$, and lead to a breakdown of the GPD moment expansion near threshold. Cross-sections for both $J/\psi$ and $\Upsilon$ are calculated with the former being compared to the data. We also demonstrate the presence of endpoint divergences for the relativistic correction away from the near-threshold regime.

Constraints on millicharged particles from nuclear gamma-decays

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2507.17955v3 Announce Type: replace-cross Abstract: We consider nuclear gamma decays and $\gamma$-emitting reactions that can be an efficient source of hypothetical millicharged particles ($\chi$). In particular, we revisit the production of millicharged particles in nuclear reactor environment, pointing out that $\gamma$ cascades from $^{239}$U is an overlooked yet a powerful source of $\chi\bar\chi$ pairs. This leads to an increased flux compared to previous studies. We then apply new estimates of the flux to derive novel limits on the value of millicharge, $\varepsilon = Q_\chi/e$, from the electron recoil searched for in a variety of experiments placed in proximity to the reactor cores. The derived limits on $\varepsilon$ are the strongest in the interval of masses $\sim 0.7-2$ MeV. We also derive the MCP flux from the Sun and point out potential sensitivity of the low-threshold dark matter search experiments.

Next-to-next-to-leading power corrections to unpolarized Semi-Inclusive Deep Inelastic Scattering

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2601.18882v2 Announce Type: replace-cross Abstract: Semi-Inclusive Deep Inelastic Scattering (SIDIS) is a key tool for exploring the three-dimensional structure of the nucleon through Transverse Momentum Dependent parton distributions and fragmentation functions. While leading-power contributions to the SIDIS cross-section are well established, next-to-leading (NLP) of order $1/Q$ and next-to-next-to-leading power (NNLP) corrections of order $1/Q^2$ to the hadronic tensor have only recently begun to be systematically investigated. These corrections are essential for the reliable phenomenology and interpretation of modern high-precision data. In recent papers by one of the authors, NNLP corrections to Drell-Yan process were derived using rapidity factorization formalism. In the present work we extend this approach to SIDIS and obtain analytic expressions for the unpolarized structure functions. We derive NNLP corrections that include convolutions of unpolarized distributions, $f_1$, with unpolarized fragmentation functions, $D_1$, and Boer-Mulders functions, $h_1^\perp$, with Collins fragmentation functions, $H_1^\perp$. We compare our results with previous formulations, provide numerical studies, confront our predictions with HERMES and COMPASS measurements, and present predictions for future experiments at Jefferson Lab and the Electron-Ion Collider.

Thermal dileptons to probe the baryon-rich QCD matter in the forward region of LHC energy heavy-ion collisions

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2606.14166v2 Announce Type: replace-cross Abstract: We investigate thermal dilepton production from a quark-gluon plasma (QGP) with finite baryon chemical potential ($\mu_{\text{B}}$) in central Pb-Pb collisions at $\sqrt{s_{\text{NN}}}=5.02~\text{TeV}$. Recent studies suggest that sizable baryon densities can be achieved at forward rapidity even at LHC energies. We incorporate finite $\mu_{\text{B}}$ into a (3+1)-dimensional hydrodynamic framework and find that $\mu_{\text{B}}$ exceeds 500 MeV around $\eta_\text{s} = 6$ during the medium evolution. Using this framework, we calculate thermal dilepton spectra over a wide rapidity range and evaluate the impact of finite $\mu_{\text{B}}$ on dilepton production. A suppression of 3-4% is observed in the forward-rapidity region $5.2 < y < 7.2$ due to the reduced quark-antiquark abundance at finite baryon density. We further examine the effective temperature extracted from dilepton mass spectra in the intermediate-mass region $1.2 < M_{\ell \ell} < 2.6~\text{GeV}$ . The effective temperature remains strongly correlated with the underlying hydrodynamic temperature and retains sensitivity to the early high-temperature stage of the QGP evolution. These results demonstrate that forward-rapidity dileptons remain effective thermometers while providing sensitivity to finite baryon density at the LHC.

Rotating magnetized pion gas of finite transverse size: condensation constraints and transport properties

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2606.20530v1 Announce Type: cross Abstract: This work investigates the electric, thermal, and thermoelectric responses of a rotating pion gas of finite transverse radius in the presence of a background magnetic field, with the rotation axis aligned with the magnetic field. We explicitly calculate the parameter limits for $\pi^+$ condensation and restrict our working regime safely outside these boundaries, ensuring well-behaved transport coefficients. Notably, the system exhibits a condensation asymmetry, with $\pi^-$ remaining uncondensed at the parameters that induce $\pi^+$ condensation. Using the Boltzmann Transport Equation under the Relaxation Time Approximation, we calculate the longitudinal electrical conductivity, thermal conductivity, and the Seebeck coefficient. Our results reveal a competing interplay between the magnetic field and rotation, highlighting the substantial impact of rotation on the medium's transport properties: while the magnetic field suppresses the transport coefficients in a static medium, rotation, acting as an effective chemical potential, introduces an energy shift that favors their increase. Beyond an angular velocity, this rotational enhancement overpowers the magnetic suppression, leading to an increase in the transport coefficients with increasing magnetic field. Finally, we analyze the relative significance of charge and heat transport through the Lorenz number, providing further insight into the transport characteristics of the rotating magnetized pion medium.

Revisiting the role of saturation in diffractive vector meson production

Fri, 19 Jun 2026 00:00:00 -0400

arXiv:2606.20362v1 Announce Type: cross Abstract: We perform a global Bayesian analysis of coherent and incoherent diffractive $\mathrm{J}/\psi$ photoproduction in $\gamma+p$ and $\gamma+\mathrm{Pb}$ collisions using a Color Glass Condensate (CGC)-based framework and ultraperipheral collision data from the Large Hadron Collider (LHC), corrected for the expected effect of electromagnetic dissociation (EMD). Using Gaussian-process emulators of the underlying CGC calculations, we infer model parameters from a combined set of HERA and LHC measurements. We find that the $\gamma+\mathrm{Pb}$ data with EMD correction substantially reduce the previously observed tension between proton and nuclear datasets, enabling a consistent simultaneous description of diffractive $\mathrm{J}/\psi$ production in $\gamma+p$ and $\gamma+\mathrm{Pb}$ collisions within the CGC framework.

Supratransmission in Lattices with Purely Nonlinear Coupling

Thu, 18 Jun 2026 00:00:00 -0400

arXiv:2606.19237v1 Announce Type: new Abstract: Supratransmission is examined in nonlinear lattices with purely nonlinear coupling, extending the phenomenon to systems that lack a linear pass band. In contrast to standard lattices with mixed linear-nonlinear interactions, the present model has no linear spectrum, so energy propagation arises entirely from nonlinear effects. Asymptotic analysis yields a discrete $p$-Schr\"odinger (DpS) equation that {provides an accurate description in the weak- and intermediate-coupling regimes and offers qualitative insight in the strong-coupling regime}. Perturbation provides analytical approximations for the critical driving amplitude, explicitly showing its dependence on the driving frequency, coupling strength, and the nonlinearity exponent $p$. The analysis identifies a non-trivial dependence of the critical amplitude on $p$, with distinct trends in different coupling regimes. Numerical continuation and direct simulations {validate the theory in regimes where the asymptotic reduction is applicable and show good agreement across a wide range of parameters}. The results establish supratransmission in fully nonlinear lattices and clarify the associated energy-transport mechanisms, with relevance to mechanical lattices, tunable metamaterials, and nonlinear optical arrays.