Clay weekly context brief for the Physics category (ISO week 2026-W39).

Clay tracks publications from the Physics feed list. Below are recent items from this category, each with its source and a short description of what the publication covers when one is available in the source feed.

Recent publications:
1. Unreported large errors from two PAMGuard three-dimensional localizers of whale calls
   Source: physics.ao-ph (Atmospheric and Oceanic Physics)
   Link: https://arxiv.org/abs/2609.20350
   Confidence intervals of location (CIL) of calling marine mammals, derived from time-differences-of-arrival (TDOA) between receivers, depend on errors of TDOAs, receiver location, clocks, sound speeds, and location method.
2. Static-to-dynamic field conversion in a temporally switched Lorentz medium
   Source: physics.app-ph (Applied Physics)
   Link: https://arxiv.org/abs/2609.19373
   We investigate static-to-dynamic electromagnetic field conversion in a temporally switched Lorentz medium initially subjected to an electrostatic field.
3. Small-Angle Differential Cross Sections for Symmetrical Resonant Charge Exchange in Molecular Hydrogen
   Source: physics.atom-ph (Atomic Physics)
   Link: https://arxiv.org/abs/2609.20381
   We measured state selective scattering angle distributions in non-dissociative-state single electron capture in $\lbrace 5, 7.5, 10\rbrace$ keV/u, $\left[\mathrm{H^+ + H_2}\right]$ and $\left[\mathrm{H_2^+ + H_2}\right]$ collisions, using Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS).
4. Agentic AI for Density-Functional Development: Revisiting r2SCAN
   Source: physics.chem-ph (Chemical Physics)
   Link: https://arxiv.org/abs/2609.19419
   We demonstrate physics-constrained agentic development of a meta-generalized gradient approximation (meta-GGA) functional using a large language model (LLM) to assist the search and optimization of a band-gap-oriented revision of r2SCAN.
5. How durable are high-performance racing shoes?
   Source: physics.comp-ph (Computational Physics)
   Link: https://arxiv.org/abs/2609.20485
   High-performance racing shoes rely on ultra-low-density elastomeric foams that undergo large, repeated deformations during running.
6. Continental-scale probabilistic resistivity imaging of Australia using deep learning: Implications for geology, groundwater, and critical minerals
   Source: physics.geo-ph (Geophysics)
   Link: https://arxiv.org/abs/2609.19516
   Electrical resistivity is a fundamental physical property that provides powerful constraints on subsurface structure, lithology, fluid distribution, and mineralization.
7. Charge Collection Efficiency in Air-Vented Plane-Parallel Ionisation Chambers at Ultra-High Dose Rates: A Self-Consistent Garfield++ Monte Carlo Model
   Source: physics.med-ph (Medical Physics)
   Link: https://arxiv.org/abs/2606.24384
   Ultra-high dose rate (UHDR) irradiation used in FLASH radiotherapy can lead to significant reductions in charge collection efficiency (CCE) in plane-parallel ionisation chambers (PPICs) due to enhanced ion recombination, while the high charge densities involved can also induce strong space-charge-induced electric-field distortions.
8. Automatic Optical Alignment Using Projective Geometry
   Source: physics.optics (Optics)
   Link: https://arxiv.org/abs/2609.19565
   Aligning and maintaining complex optical beam paths is a central challenge across experimental science, because it is a high-dimensional task with strong cross-coupling between controls, often in systems with limited physical access.
9. Efficient laser ion acceleration in near-critical density plasmas in the picosecond pulse regime
   Source: physics.plasm-ph (Plasma Physics)
   Link: https://arxiv.org/abs/2609.19571
   Kilojoule-class short-pulse (< 10 ps) lasers are excellent tools for generating relativistic ion beams, but achieving high laser-to-ion conversion efficiency remains an open challenge.
10. The HANDY model with non-renewable resources and societal effects
   Source: physics.soc-ph (Physics and Society)
   Link: https://arxiv.org/abs/2609.20244
   We present an extension of the single-population Human and Nature Dynamics (HANDY) model that explicitly incorporates non-renewable resources and societal effects.
11. AlchemQ: Proof-Carrying Quantum Circuit Optimization with Per-Result Equivalence Certificates
   Source: quant-ph (Quantum Physics)
   Link: https://arxiv.org/abs/2609.19160
   We present AlchemQ v0.5, a proof-of-concept system that couples an untrusted beam-search optimizer with a machine-checkable per-result certification layer and a versioned certificate protocol (0.2.0), so that every optimized circuit ships with a verifiable artifact rather than a bare claim.
12. Three-dimensional shock-weak-discontinuity interactions: curvature deposition and post-shock flow response
   Source: physics.flu-dyn (Fluid Dynamics)
   Link: https://arxiv.org/abs/2609.20289
   A weak acoustic, entropy or vortical sheet can cross a finite-strength three-dimensional shock without producing a kink, yet it can deposit a discontinuity of curvature along the intersection curve.
13. TCAD + Allpi$\text{x}^2$ Simulation study of MALTA2, a Depleted Monolithic Active Pixel Sensor for future tracking
   Source: physics.ins-det (Instrumentation and Detectors)
   Link: https://arxiv.org/abs/2605.23860
   In this work, a hybrid simulation framework combining TCAD and Allpi$\text{x}^2$ is presented to investigate the sensor properties of MALTA2, a depleted monolithic active pixel sensor designed for future tracking.
14. Ultralow Mean Transverse Energy and High Quantum Efficiency Cryogenic Bialkali Photocathode for MHz-Repetition-Rate Electron Sources
   Source: physics.acc-ph (Accelerator Physics)
   Link: https://arxiv.org/abs/2609.18137
   Simultaneously achieving high quantum efficiency (QE), ultralow mean transverse energy (MTE), and robust long-term operation under conditions relevant to continuous-wave (CW) X-ray free-electron lasers (XFELs) remains a central challenge for semiconductor photocathodes.
15. What is superatom?
   Source: physics.atm-clus (Atomic and Molecular Clusters)
   Link: https://arxiv.org/abs/2608.14739
   The term "superatom" was introduced over three decades ago to describe clusters that emulate elemental atoms.
16. Multi-contrast wide-field mid-infrared photothermal imaging
   Source: physics.bio-ph (Biological Physics)
   Link: https://arxiv.org/abs/2609.18376
   Wide-field mid-infrared photothermal (MIP) imaging enables high-speed, chemically specific imaging at sub-micrometer spatial resolution through several possible contrast mechanisms, including scattering change, fluorescence modulation, and phase change.
17. Impact of Phase Unwrapping on Multitarget Acoustic Lenses for Transcranial Holography
   Source: physics.class-ph (Classical Physics)
   Link: https://arxiv.org/abs/2609.18495
   Acoustic lenses have been introduced recently to compensate for the phase distortions induced by the propagation across a human skull for ultrasonic deep-brain stimulation in humans.
18. Deriving Ontological Statements from the Unnatural Higgs Mass
   Source: physics.hist-ph (History and Philosophy of Physics)
   Link: https://arxiv.org/abs/2403.20282
   We provide novel, metatheoretical arguments strengthening the position that the naturalness problem of the light Higgs mass is a pseudo-problem: Under one assumption, no physics beyond the standard model of particle physics is needed to explain the small value of the Higgs boson.
19. Resistive instabilities of current sheets in stratified plasmas with a gravitational field
   Source: physics.space-ph (Space Physics)
   Link: https://arxiv.org/abs/2602.17400
   Magnetic reconnection can develop spontaneously via the tearing instability, often invoked to explain disruptive instabilities in fusion devices, solar flares, the generation of periodic density disturbances at the tip of helmet streamers, and flux transfer events at the Earth's dayside magnetopause.
20. Probing Non-Cold Dark Matter with Modified Emergent Dark Energy
   Source: physics.gen-ph (General Physics)
   Link: https://arxiv.org/abs/2609.16068
   In the standard $\Lambda$CDM cosmology, dark matter is assumed to be a pressureless cold fluid with $w_{\rm dm}=0$.
21. Analytical and Experimental Study of a Variable-Mass Oscillator with Constant Mass Loss
   Source: physics.ed-ph (Physics Education)
   Link: https://arxiv.org/abs/2609.16845
   We present an analytical and experimental study of a variable-mass oscillator with constant mass loss.
22. Spatial Aggregation of ROC and Precision-Recall Curves
   Source: physics.ao-ph (Atmospheric and Oceanic Physics)
   Link: https://arxiv.org/abs/2609.19517
   Receiver Operating Characteristic (ROC) and Precision-Recall (PR) curves are widely used to assess the discrimination ability of forecasts for binary events, such as threshold exceedances or warnings of extreme events.
23. Energy Harvesting for Self-Powered Microsystems: A Critical Review of Materials, Power Management, and System Integration
   Source: physics.app-ph (Applied Physics)
   Link: https://arxiv.org/abs/2609.20157
   The relentless proliferation of the Internet of Things (IoT), wearable bioelectronics, and cyber-physical infrastructure has rendered the conventional electrochemical battery the single most prohibitive bottleneck to long-term, maintenance-free autonomous microsystems.
24. Effective Conservation and Bistability of Atomic Alignment under Strong Spin~Exchange
   Source: physics.atom-ph (Atomic Physics)
   Link: https://arxiv.org/abs/2609.20741
   We present a phenomenological model of anomalous alignment signals in dense cesium vapor under linearly polarized pumping and fast spin exchange near zero magnetic field.
25. DFT GGA based datasets for H$_2$O potential energy surfaces, permanent moment and polarizability tensors
   Source: physics.chem-ph (Chemical Physics)
   Link: https://arxiv.org/abs/2609.19469
   We present in this article data on the computed potential energy surface, permanent moment surface (from dipole to hexadecapole) and polarizability surface (from dipole-dipole to quadrupole-quadrupole) for the H$_2$O molecule, calculated at the level of the generalized gradient approximation (GGA) in Kohn-Sham density functional theory (KS-DFT) in the grid-based projector augmented wave code GPAW, using the charge perturbation code C-pol.
26. How Does Distribution Shift Shape Pretraining Gains in Neural PDE Surrogates?
   Source: physics.comp-ph (Computational Physics)
   Link: https://arxiv.org/abs/2609.20814
   Pretraining a neural PDE surrogate can reduce the amount of new CFD data needed when geometry or modeled physics changes.
27. The Brittle-Plastic Transition in Quartz-Albite Mixtures: New Insights From Shear Deformation Experiments at Mid-to-Lower Crustal Depth Conditions
   Source: physics.geo-ph (Geophysics)
   Link: https://arxiv.org/abs/2609.19645
   Crustal strength is often characterized using a strength-depth profile where laboratory-derived friction and flow laws are connected at depth (i.e., the so-called Christmas Tree diagram).
28. Constrained estimation of rotational invariants of the cumulant expansion (RICE) for rapid tensor-valued diffusion MRI
   Source: physics.med-ph (Medical Physics)
   Link: https://arxiv.org/abs/2608.27212
   Purpose: To complement 1.5-minute measurements of common tensor-valued diffusion MRI (dMRI) markers with rapid constrained fitting.
29. Limits on the free-space group velocity of optical wave packets incorporating angular dispersion. Part~I, conventional angular dispersion: tutorial
   Source: physics.optics (Optics)
   Link: https://arxiv.org/abs/2609.19576
   A plane-wave optical pulse travels in free space at a group velocity $c$ (the speed of light in vacuum) measured along its propagation axis.
30. Indirect-Drive Fusion Target Design for Commercial Fusion Energy
   Source: physics.plasm-ph (Plasma Physics)
   Link: https://arxiv.org/abs/2609.19752
   This paper presents the physics basis for commercially relevant laser indirect-drive (LID) (radiation-driven) inertial fusion energy (IFE) using a 10 MJ laser driver.

Sources in this brief: physics.acc-ph (Accelerator Physics); physics.ao-ph (Atmospheric and Oceanic Physics); physics.app-ph (Applied Physics); physics.atm-clus (Atomic and Molecular Clusters); physics.atom-ph (Atomic Physics); physics.bio-ph (Biological Physics); physics.chem-ph (Chemical Physics); physics.class-ph (Classical Physics); physics.comp-ph (Computational Physics); physics.ed-ph (Physics Education); physics.flu-dyn (Fluid Dynamics); physics.gen-ph (General Physics); physics.geo-ph (Geophysics); physics.hist-ph (History and Philosophy of Physics); physics.ins-det (Instrumentation and Detectors); physics.med-ph (Medical Physics); physics.optics (Optics); physics.plasm-ph (Plasma Physics); physics.soc-ph (Physics and Society); physics.space-ph (Space Physics); quant-ph (Quantum Physics).
Selected 30 of 351 available items for this weekly brief.