High Energy Physics (Theory)
Evading the Swampland de Sitter Obstruction via Thermodynamic Duality-Induced Horizon Corrections in Unimodular Gravity
Reza Baghbani
We investigate the early-universe cosmological implications of Unimodular
Gravity coupled to Power-Law Nonlinear Electrodynamics in the presence of
quantum-corrected horizon thermodynamics derived from the principle of thermodynamic duality. By incorporating both logarithmic and inverse-area corrections to the Bekenstein-Hawking
entropy, we derive modified Friedmann equations exhibiting novel $H^4$ and $H^6$ terms that represent genuine
quantum gravity effects. We demonstrate that these higher-order corrections become dynamically significant in the high-energy regime of
cosmic inflation, naturally modifying the slow-roll dynamics without requiring a fundamental inflaton potential. A comprehensive phase-space analysis reveals that the
quantum corrections drive early-time de Sitter-like attractors, providing a robust mechanism for sustained inflationary expansion. Confronting the model with the Swampland program, we show that the correction factor $\mathcal{F}(H)$ modifies the effective slow-roll parameters, enabling the model to satisfy the Swampland de Sitter and Distance
conjectures during the inflationary epoch. We calculate the inflationary observables, including the spectral index $n_s$ and the tensor-to-scalar ratio $r$, and demonstrate that the model's predictions are in excellent agreement with the Planck 2018 observational constraints. Our results suggest that thermodynamic duality-induced horizon corrections offer a viable and testable pathway for realizing successful inflation within a well-motivated
quantum-gravitational framework.
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High Energy Physics (Theory)
Type I-II/II-I vortices from dimension-six self-interaction
A. Alonso-Izquierdo, A. González-Parra, K. Slawinska et al. (+2 more)
We show that adding a dimension-six self-interaction to the Abelian-
Higgs or Ginzburg Landau model results in a remarkable and rich structure of multi-
vortex solutions. Besides the standard type I (attractive) and type II (repulsive) regimes, separated by the Bogomol'nyi-Prasad-Sommerfeld limit (BPS), we identify two new possibilities: type I-II
vortices, which attract at short distances and repel at long distances; and type II-I
vortices, with the opposite behaviour. Specifically, within the type II-I regime, multi-
vortex solutions form chunks of the Abrikosov
lattice or clusters. Conversely, in the I-II regime, axially symmetric multi-
vortices are stable; nevertheless, depending on the model parameters and topological charge (winding number), they can be either the ground state or not.
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All authors A. Alonso-Izquierdo, A. González-Parra, K. Slawinska, A. Wereszczynski, T. Winyard
Solar and Stellar Astrophysics
What Does 2D Coronal Seismology Measure?
Zihao Yang, Yuhong Fan, Giuliana de Toma et al. (+2 more)
Two-dimensional (2D) coronal seismology based on coronagraphic imaging spectroscopy has emerged as a promising method for mapping the coronal
magnetic field, but the physical meaning of its inferred quantities under optically thin line-of-sight (LOS) integration remains uncertain. We investigate this problem by synthesizing coronagraphic observables from a global wave-driven magnetohydrodynamic model with a long LOS extent and a structured corona, and by applying the same analysis procedures used for observations. We compare the diagnosed density, wave propagation direction, phase speed, and
magnetic-field strength with different LOS-weighted reference quantities from the model. We find that the measured density and the wave propagation direction are both well represented by LOS emissivity-weighted quantities. In contrast, the phase speed is not controlled by emissivity weighting alone: the LOS distribution of wave velocity amplitude also plays an important role. As a result, the inferred
magnetic field is better represented by combining the emissivity-weighted density with an amplitude-dependent effective speed. Emissivity weighting nevertheless remains a reasonable approximation, and a useful baseline, over much of the field of view, especially where the LOS does not cross strongly structured
plasma-sheet-like regions. These results clarify the physical interpretation of 2D coronal seismology and provide guidance for future coronal
magnetic-field
tomography and model-constrained applications.
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All authors Zihao Yang, Yuhong Fan, Giuliana de Toma, Sarah Gibson, Matthias Rempel
Computational Physics
KINTORA: a semi-Lagrangian discontinuous Galerkin drift-kinetic, unstructured mesh tokamak solver
Mark F. Adams
Continuum gyrokinetic codes use structured, field-aligned grids on nested flux surfaces; particle-in-
cell codes support unstructured meshes and open field lines but carry a statistical noise floor. We present a continuum drift-kinetic solver that occupies neither position: a semi-Lagrangian discontinuous Galerkin discretization on unstructured triangular poloidal planes extruded toroidally, whose parallel advance is a map along the exact field line in the flux-coordinate independent manner, so the mesh is never aligned with the field, with adiabatic electrons and a long-wavelength polarization field solve. Every operator is verified against an independently computed reference, from Landau damping to the geodesic-acoustic root and a linear ion-temperature-gradient
eigenvalue problem, every measured rate within 4% except the geodesic-acoustic damping, within 12%. A linear toroidal ion-temperature-gradient demonstration on a canonical-Maxwellian
equilibrium recovers a radially coherent mode whose growth rate, 0.065 c_s/a, is stationary in time. The collisionless zonal-flow residual is the one measurement still moving: it rises with poloidal refinement from 0.72 to 0.87 of the model's own orbit-quadrature prediction for the measured observable and has not converged. The solver is fully device resident, and every result is reproduced between CPU and GPU builds and across MPI process counts. The code, the data behind every table and an artifact description are in a public repository.
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Nuclear Theory
Internal Nucleon Properties and the Equation of State of Ultra-Dense Matter
Bikram Keshari Pradhan, Jérôme Margueron, Guy Chanfray et al. (+1 more)
The question of the link between the nucleon properties and the equation of state of ultra-dense matter, both being composed of
quarks and gluons, is investigated by adopting a
soliton model to describe internal nucleon properties and a direct mapping between nucleon and
quark matter to obtain the equation of state of ultra-dense matter. We compare $\pi+\omega$ and $\pi+\omega+\rho$
soliton models and analyze the presence of a pressure singularity at the nucleon center due to the $\rho$ field. This singularity impacts the equation of state in ultra-dense matter. Only the pressure derived from the canonical energy-momentum tensor has a singularity, while the Belinfante pseudo-gauge transformation of the energy-momentum tensor generates an internal pressure without a singularity. We then investigate predictions for the equation of state of ultra-dense matter based on different prescriptions for the nucleon pressure. It is shown that none of the prescriptions agree with the thermodynamical pressure defined in uniform matter. The mismatch between any equation of state and the thermodynamical one questions the simplicity of the direct mapping between finite-size nucleon properties and uniform matter as well as the role of the nucleon surface in the internal energy density and the pressure.
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All authors Bikram Keshari Pradhan, Jérôme Margueron, Guy Chanfray, Hubert Hansen
Materials Science
High-Resolution X-ray Spectro-Microscopy of Au Microcrystallites
Chaitali Sow, Martin Seyrich, Johannes Hagemann et al. (+4 more)
Understanding the functionalities of heterogeneous catalysts requires high-resolution nanoscale chemical imaging tools. X-ray spectro-ptychography offers this capability by enabling X-ray absorption near edge structure (XANES) based amplitude and phase contrasts imaging with high spatial resolution. However, such demonstrations at energies above 10 keV, such as the Au L-edges, remain limited due to weak X-ray absorption cross-sections and correspondingly, low signal levels. Here,
multimodal spectro-microscopy has been performed on Au microcrystallites that host both conventional face-centered cubic (fcc) and unconventional non-cubic
lattices, particularly important for catalysis. Amplitude and phase contrasts across the $\mathrm{L}_3$ edge are resolved on thin Au crystallites (150 nm to 1.71 $\mu\mathrm{m}$) with 45 nm spatial resolution. The resulting XANES spectra exhibit excellent agreement with standard transmission and fluorescence contrasts, while providing complementary chemical insights with improved spatial resolution. Quantitative
retrieval of anomalous phase variations ~12 keV further demonstrates the suitability of this method for high-resolution chemical imaging across a wide range of functional materials.
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All authors Chaitali Sow, Martin Seyrich, Johannes Hagemann, Giridhar U. Kulkarni, Thomas F. Keller, Christian G. Schroer, Andreas Schropp
Solar and Stellar Astrophysics
Henrietta Leavitt's classical Cepheid relation
Daniel Majaess
The Leavitt & Pickering (1912) mean period-magnitude relation for SMC Cepheids exhibits correlated residuals relative to modern Gaia $B_G$ and Johnson $V$ photometry ($r_{\delta V/\delta L12}\approx0.76$). Therefore dispersion inherent to Leavitt's photographic photometry relation is not solely random scatter ($\sigma_{L12,B_G,V}=0.22\pm0.03,0.25\pm0.04,0.20\pm0^{m}.03$), and is potentially consistent with the partial encoding of combined effects from the elongated SMC, classical Cepheid instability strip, differential reddening, etc. OGLE data indicate that $\gtrsim870$ SMC variables identified by Leavitt (1908, Table 2) are classical Cepheids ($\gtrsim 90$ %), and the preliminary unphased Table 2 photometry likewise features correlated residuals relative to contemporary observations ($r_{\delta B_G/\delta L08-T2}\approx0.54$). Table 6 data in Leavitt (1908, $n=16$) define a highly linear Leavitt law over an extensive baseline ($r\approx-0.98$), but constitute a smaller sample than the later 1912 work ($n=25$).
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Instrumentation and Methods for Astrophysics
Simulation and Deep Learning Inversion for Full-sky Energetic Neutral Atom Imaging at the Heliospheric Boundary
Weining Wang, Rong Lin, Jiansen He et al. (+11 more)
The distribution of energetic neutral atom (ENA) differential flux density at the heliospheric boundary is the key to revealing the interaction mechanism between the solar wind and the interstellar medium. The Helios ENA Rapid Mapper (HERMA) is a pre-research project for a new ENA detection concept and technical principle, which is designed to provide technical support for refined detection with its advantages of wide energy range coverage and high spatial resolution. To verify the high spatiotemporal resolution rapid imaging capability of the HERMA, this study restored the particle response characteristics of the HERMA (spatial modulation grid + 256-pixel linear array silicon detector) based on Geant4 simulation, and we compared the performance of the traditional inversion
algorithm with the convolutional neural network (CNN) inversion
algorithm using INCA data as the
benchmark. The results show that under different sampling times, the source distribution inverted by the CNN
algorithm has a higher degree of agreement with the ideally expected distribution, and the CNN
algorithm exhibits better stability and accuracy than the traditional
algorithm under the conditions of low signal-to-noise ratio and short staring time. This study provides core technical support for the engineering verification and on-orbit application of the HERMA instrument, fills the technical gap in wide-energy-range and high-resolution ENA detection, and helps to deepen the research on the interaction mechanism between the solar wind and the interstellar medium at the heliospheric boundary.
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All authors Weining Wang, Rong Lin, Jiansen He, Hong Zou, Yongfu Wang, Jiali Chen, Yuguang Ye, Weihong Shi, Wei Zhang, Xi Lu, Die Duan, Tianhang Chen, Linghua Wang, Qiugang Zong
Fluid Dynamics
A complete forward projection algorithm through cylindrical and spherical refractive windows
Shijie Zhong, Shiyong Tan, Xiaosi Zhang et al. (+2 more)
Cylindrical or spherical windows often appear in experiments and real applications. Measuring through those windows requires projecting 3D points to pixels, which is different to compute due to refraction. A point may have multiple projected images but cannot be efficiently determine with the existing projection
algorithms. Using the ray's conserved momenta, we reduce this projection to closed-form equations with a concave structure. As a result, we can successfully determine whether a 3D point has a single projection or multiple and compute those locations. In simulations, with one single search, we can recover images that iterative methods miss even with many restarts. A wand calibration based on it can reach the precision limit set by image noise, enabling accurate 3D particle tracking in a swirling flow through cylinder windows. This
algorithm shows how to predict visibility and multiple images through curved windows, shedding light for 3D pipe flow measurements, accurate underwater reconstruction, and many real applications.
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All authors Shijie Zhong, Shiyong Tan, Xiaosi Zhang, Yanying Li, Rui Ni
Geophysics
Event-Centric Earthquake Monitoring with a Multi-Station Transformer
Haoyu Wang and Weiqiang Zhu
Earthquake catalogs underpin studies such as fault structure, earthquake processes and seismic hazard, and their value depends on being both complete and reliable. Machine learning has improved individual tasks of earthquake monitoring, but processing stations independently discards the consistency of arrivals across the network, and running tasks in sequence fragments the information describing each earthquake. We present EQNet2, a geometry-aware multi-station
Transformer that jointly predicts phase arrivals, first-motion polarities, source location and magnitude, and the association of arrivals into events. On a Northern California test
dataset and on continuous waveforms from Ridgecrest and the San Francisco Bay Area, EQNet2 recovers more weak arrivals, produces fewer false detections, and associates more picks into located events. Its learned
attention links information across stations along time–distance patterns consistent with seismic moveout. As seismic networks grow denser, exploiting multi-station coherence and event-centric prediction offers a path to more complete and reliable catalogs.
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Mathematical Physics · Cross-listed from math.AP
Fresnel scattering for open waveguide networks
Solomon Quinn and Charles L. Epstein
This paper concerns the Helmholtz scattering problem for open waveguide networks, extending the analysis from [arXiv:2302.04353, arXiv:2310.05816, arXiv:2401.04674] to plane-wave incident data. We first reduce the problem to a Fredholm second-kind integral equation on an infinite interface. This produces an integral representation of the solution to the original scattering problem, which is then used to obtain detailed asymptotic estimates of the solution at infinity. To leading order and away from the waveguides, the scattered field is itself a plane wave. Its amplitude and phase shift exhibit a jump across a critical polar angle depending on the direction of the incident plane-wave. Our estimates also imply that the scattered field is outgoing in a weak sense, allowing us to establish a uniqueness result. We conclude by calculating the waveguide-mode contributions to the scattered field in a perturbative regime.
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Quantum Physics
A Controlled Null Result for Per-Gate Riemannian Optimization in VQE
Polina Belozerova and Pavel Osinenko
Parametrized gates in a variational
quantum eigensolver (VQE) live on a product of
unitary groups, which makes Riemannian optimization a natural candidate for improving training. We test this candidate in the clean per-gate setting: each single-
qubit gate is optimized directly on U (2) and compared with Adam on an unconstrained Euler-angle chart representing the same physical gate, initialized from the same
unitaries and tuned with a separate learning-rate sweep. On a validated hydrogen-chain
benchmark, we find no measurable practical advantage from the Riemannian machinery. The direct
manifold optimizer and the Euler-coordinate baseline are interleaved in final error and success rate; the classical coordinate baseline is not slower in iterations on the successful
cells; and the choices of Riemannian metric, retraction, and momentum vector transport do not change the conclusion. We also identify four failure modes that can manufacture an apparent positive result: a trivial product-state
benchmark, a projected-
matrix Adam baseline that discards most of its own step, a non-
unitary inherited Cayley retraction that lets the reported energy pass below the variational minimum, and a learning-rate grid whose optimum sits at its boundary. Each failure mode produced a plausible multi-seed result in our own workflow before being caught. The practical output of this paper is therefore a controlled null result and a validation checklist for VQE optimizer comparisons.
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Computational Physics · Cross-listed from math.NA
A Method for Exact Enforcement of Boundary Conditions on General Curved Triangular Domains: Algorithm and Application to Scientific Machine Learning
Suchuan Dong and Yuchuan Zhang
We present a method for enforcing exactly Dirichlet, Neumann, and Robin conditions on general triangular domains with arbitrarily curved boundaries. The algorithmic constructions developed here complements those in a previous work for general quadrilateral domains. Our method combines (i) the exact mapping between a general curved triangular domain and the standard triangle, (ii) TFC constrained expressions, and (iii) Barnhill transfinite interpolations, to provide explicit closed-form trial ansatze that mathematically satisfy the imposed boundary conditions exactly. Corner compatibility induced by the boundary conditions is pivotal, and enforcing exactly the imposed boundary conditions hinges on the exact enforcement of the induced compatibility constraints. The corner compatibility associated with the acute vertices of the standard triangle and the coupling between gradient components when the hypotenuse corresponds to a Neumann/Robin boundary pose particular challenges. Two strategies are critical to resolving these issues, by reformulating conditional corner constraints into equivalent unconditional forms and by introducing a separate TFC-style auxiliary edge construction together with an associated linear solve on the hypotenuse. We analyze the corner compatibility constraints and present formulations for the general form of functions that exactly satisfy the imposed Dirichlet, Neumann, or Robin conditions on curved triangular domains. The proposed method has been implemented using extreme learning machine type randomized neural networks for solving PDE problems. We present ample numerical experiments with linear/nonlinear PDE problems on a variety of domains with complex boundary geometries. Numerical results show that the current method has enforced the Dirichlet, Neumann, and Robin conditions on curved domain boundaries to the machine precision.
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Astrophysics of Galaxies
Intermittency in the Multiphase ISM — II. Non-Gaussian Dust Polarization and Foreground Variance
Yue Hu
Interstellar
turbulence produces non-Gaussian polarized Galactic dust emission whose higher-order statistics depend on thermal phase and turbulent forcing. We synthesize optically thin dust polarization from three thermally multiphase diffuse interstellar medium (ISM) simulations with compressive, mixed, and solenoidal forcing. We characterize the resulting non-Gaussian structure in the warm, unstable, and cold phases using $E$- and $B$-mode spectra, one-point distributions, scale-dependent increments, and Minkowski functionals. Both $E$ and $B$ modes are intermittent. Warm-phase emission remains closest to Gaussian, whereas cold gas shows flatter intermediate-scale spectra, broader non-Gaussian tails, and the strongest departures from Gaussian morphology. Compressive forcing generally produces the strongest projected intermittency, particularly in the cold phase and total emission, while mixed and solenoidal forcing show weaker signatures. These higher-order structures also enhance spatial fluctuations in polarized dust power: Gaussian fields matched to the same two-point covariance underestimate the region-to-region scatter by factors of up to $\sim2.6$. Our results show that thermal phase and turbulent forcing regulate not only the mean polarized dust spectrum but also the field-to-field distribution of foreground power, with implications for modeling Galactic foreground in CMB polarization measurements.
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Earth and Planetary Astrophysics
Ultraviolet Reflected-Light Spectroscopy of Modern Earth Analogs with Starshade Observations
Zahra Ahmed, Stuart Shaklan, Mario Damiano et al. (+3 more)
Characterizing rocky, habitable zone
planets in reflected light is a key science objective for future direct imaging missions, and the ultraviolet (UV) is uniquely suited for supporting the characterization of Earth-like atmospheres. The Hartley-Huggins ozone band at $0.25 ~\mu\mathrm{m}$ remains detectable at low spectral resolution down to $0.1\%$ PAL $\mathrm{O}_2$, providing a sensitive proxy for oxygen-bearing chemistry even for Proterozoic-like atmospheres where the visible and near-infrared $\mathrm{O}_2$ features become inaccessible. This work uses an end-to-end framework for UV starshade spectroscopy of modern Earth analogs that integrates high-fidelity observation simulation, conservative post-processing, and
Bayesian spectral
retrieval to quantify ozone detection significance. The framework is applied across 108 simulated scenes spanning a range of
planet phase angles, system inclinations, and exozodiacal dust densities. The results establish that robust ozone detection with UV-only, $R=7$ reflected light spectroscopy requires a photometric $\mathrm{SNR} \sim 30$. UV starshade observations with the Habitable Worlds Observatory achieve this threshold within 3-day integrations for solar-type systems at 10 parsecs with inclinations up to $60^\circ$ at favorable phases ($\leq 90^\circ$). Above this SNR threshold, ozone detections are robust to systematic bias from imperfect exozodi calibration within $\sim30\%$, and the median retrieved ozone abundance remains accurate to within one order of magnitude of the true value.
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All authors Zahra Ahmed, Stuart Shaklan, Mario Damiano, Armen Tokadjian, Edward W. Schwieterman, Simone D'Amico
Instrumentation and Detectors
FINESSE: A Versatile Beamline for Fundamental Interactions with Neutrons at the European Spallation SourcE
J. Amaral, J. Barrow, M. Bartis et al. (+71 more)
FINESSE (A Versatile Beamline for Fundamental Interactions with
Neutrons at the European Spallation SourcE) is a proposed versatile beamline for fundamental interactions with
neutrons at the European Spallation Source. Building on the HIBEAM design studies, FINESSE extends the original concept into a dual-guide beamline capable of operating either in a high-flux configuration or in a low-background configuration within a single ESS beam port. The high-flux branch is optimized for rare-process searches, including
neutron–antineutron oscillations,
neutron–sterile-
neutron transitions,
axion-like-particle searches,
neutron charge measurements, and rare
neutron decays. The low-background branch is designed for precision measurements requiring strong suppression of
prompt and line-of-sight backgrounds, with a cryogenic
neutron electric-dipole-moment experiment used as a
benchmark case. A baseline exchangeable-guide concept has been developed in which only short guide sections inside the ESS bunker are exchanged, while the upstream extraction system and chopper positions remain fixed. A staged implementation, Short FINESSE, would use the upstream section of the high-flux beamline together with a compact magnetically controlled experimental region, enabling an early physics and R&D programme before completion of the full facility. This paper summarizes the scientific case, beamline concept, guide simulations, chopper and timing system,
magnetic-field control, detector developments, and staged implementation strategy. FINESSE would establish a long-term particle-physics infrastructure at ESS, providing a beamline for both discovery-driven searches and precision
neutron measurements throughout the lifetime of the facility.
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All authors J. Amaral, J. Barrow, M. Bartis, D. H. Beck, P. M. Bentley, J. Bijnens, G. Brooijmans, L. J. Broussard, A. Burgman, G. Cibinetto, G. Croci, D. D. Di Julio, P. Fierlinger, B. W. Filippone, C. Gatto, H. Gisbert, H. Gogoi, G. Gorini, A. Gutierrez-Rodriguez, A. Koberinski, M. Kaczmarek, M. Silarski, M. O'Riordan, A. Heinz, J. Henderson, M. Holl, H. T. Johansson, B. Jonsson, H. Henriksson, L. Jonsson, Y. Kamyshkov, M. P. Kuhl, P. Kinhult, R. Kolevatov, A. Kozela, W. T. Lee, K. K. H. Leung, T.-J. Liang, G. Luzin, B. Meirose, D. Milstead, R. Mohapatra, G. Muhrer, A. Muraro, A. Nepomuceno, N. Okada, A. Oskarsson, T. Palasz, R. Pasechnik, V. Larsson, L. B. Persson, O. Putignano, J. Ramsey, C. Snow, L. Werselius, B. Rataj, A. Rodriguez-Sanchez, A. Saunders, V. Santoro, F. Scioscioli, R. Shrock, D. Silvermyr, H. Sina, W. M. Snow, Y. V. Stadnik, L. Tchelidze, N. Tsapatsaris, A. Tureanu, A. Vilela Pereira, M. Wolke, J. Womersley, S. Xu, A. R. Young, K. Osterberg
Quantum Physics
Periodic-Pulse Control of Collective Emission and Photon Statistics in Interacting Quantum Emitters
Kavalambramalil George Paulson, Fu Li and Hanna Terletska
We investigate the collective emission spectra and
photon correlations of two identical dipole-dipole-coupled emitters under continuous-wave (CW) and periodic pulsed driving. Our results show that a periodic train of instantaneous $\pi_x$ pulses can generate emission spectra whose dominant features closely resemble those obtained under CW excitation. We find that the structure of the collective emission spectra reflects the interplay among the resonance conditions, dipole-dipole coupling, and the inter-pulse delay $\tau_D$. We further demonstrate that finite-duration $\pi_x$ pulses with sufficiently high Rabi frequencies can closely reproduce the ideal instantaneous-pulse limit. In contrast to the emission spectra, the
photon correlations $g^{(2)}(t,\tau)$ are governed primarily by $\tau_D$ and, unlike under CW driving, become increasingly insensitive to the resonance conditions in the short-pulse limit. These results establish periodic pulsed driving as a versatile means of tailoring both the emission spectra and the
photon statistics of coupled two-emitter systems.
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Computational Physics
Wisevolve Potential Engine: Machine-Learning Molecular Dynamics at 100 Million Atom-Steps per Second on a Single GPU
Hekai Bu and Zheyong Fan
General-purpose molecular dynamics software supports diverse interatomic potentials and simulation requirements. Within a simulation stage, the loaded potential model and the required calculations typically remain fixed as the atomic configuration evolves. We present the Wisevolve Potential Engine (WPE), which uses this information from GPUMD to select and reuse a GPU execution policy tailored to the model and simulation stage. GPUMD retains simulation control and ownership of the simulation data. On a single NVIDIA RTX 5090, WPE-enabled GPUMD (GPUMD-WPE) achieves a median throughput of 109 million atom-step/s across 106 neuroevolution potential (NEP) workloads. For a 15.1-million-atom diamond Si system, it sustains 142 million atom-step/s. Relative to GPUMD,
geometric-mean speedups are 3.49x across these NEP workloads, 3.61x across 16 workloads using NEP with dynamic charges (qNEP), 1.24x across 28 classical-potential workloads, and 10.5x across 56 path-integral molecular dynamics (PIMD) configurations. End-to-end calculations of water structure,
lattice thermal conductivity, and PIMD thermal expansion show close agreement with corresponding GPUMD results and published simulation results. A separate 12.5-million-atom Cu shock-compression simulation demonstrates its applicability to large-scale nonequilibrium dynamics. These results support model- and stage-specific specialization as a practical way to accelerate GPU potential evaluation in general-purpose molecular dynamics workflows.
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Optics
Zeptosecond-level timing-noise floor in optical-to-terahertz photomixing
William F. McGrew, James Greenberg, Scott C. Egbert et al. (+6 more)
Optical generation of terahertz (0.1 to 10\,THz) carriers can, in principle, preserve the spectral purity of an optical reference without the noise penalty associated with electronic frequency multiplication. Here, we identify and suppress the dominant excess-noise mechanisms that limit this conversion in high-power uni-travelling-carrier photodiodes. We characterize amplitude-to-phase conversion as functions of photocurrent and reverse bias and identify operating parameters to minimize the effect. We quantify the white phase noise introduced by optical amplification and show that this contribution can be eliminated by directly driving the photodiode with a high-power optical source. With the excess noise mitigated, we use cross-correlation phase-noise measurements to observe a white phase-noise floor of $-161.0$~dBc/Hz at 263.2~GHz, corresponding to a timing-noise floor of 7.6~zs/$\sqrt{\mathrm{Hz}}$. The remaining floor follows the photocurrent dependence expected from shot noise. Extending the measurement across the full WR-3.4 band, from 220 to 330~GHz, yields timing-noise floors below 10~zs/$\sqrt{\mathrm{Hz}}$ throughout, with a minimum of 6.0~zs/$\sqrt{\mathrm{Hz}}$. These results establish direct photomixing as a route to sub-10-zs/$\sqrt{\mathrm{Hz}}$ white timing-noise floors for continuous-wave sources at terahertz frequencies and identify the noise processes that must be controlled to reach this regime.
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All authors William F. McGrew, James Greenberg, Scott C. Egbert, Brendan M. Heffernan, Y. Lange Simmons, Tatsuya Tanigawa, Kazutoshi Kato, Tadao Nagatsuma, Antoine Rolland
High Energy Physics (Theory)
Yang-Baxter deformed sigma models on $\mathrm{SU}(N)/\mathrm{SO}(N)$
Danila Alexandrov, Alexey Bychkov, Ivan Kalinichenko et al. (+1 more)
We study Yang–Baxter deformations of two-dimensional sigma models on compact symmetric spaces $\mathrm{SU}(N)/\mathrm{SO}(N)$, with particular emphasis on their ultraviolet behavior. We claim that the ultraviolet fixed point is described by the $\mathrm{SO}(N,\mathbb C)/\mathrm{SO}(N,\mathbb R)$ non-compact WZW model together with $N-1$ compact free
bosons. We determine the leading correction to this fixed point and identify it with the perturbation generated by the corresponding screening currents. We also extend our construction to the broader class of symmetric spaces of maximal rank.
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All authors Danila Alexandrov, Alexey Bychkov, Ivan Kalinichenko, Alexey Litvinov
Materials Science
Collision Cascade Morphology and Defect Nucleation in Pure Tungsten and an Equimolar Refractory W-Ta-Cr-V Alloy
Mark Fedorov, Francisco Javier Dominguez-Gutierrez, Damian Kalita et al. (+1 more)
Collision cascades and defect-formation mechanisms in pure W and the WTaCrV refractory high-
entropy alloy were investigated using molecular dynamics simulations over primary knock-on atom (PKA) energies of 0.1-100 keV. Machine-learning tabulated Gaussian approximation potentials (tabGAP), complemented by short-range Ziegler-Biersack-Littmark (ZBL) interactions, were employed. Analysis of the heat spike lifetime, affected region, atomic relocations and surviving defects reveals an importance of subcascade formation and presence of light elements in the
alloy. Cascade splitting into subcascades contributes to the distribution of the PKA energy over a larger region in the material, nucleating less dislocations and smaller voids - latter being present only in W and absent in WTaCrV. Since cascade splitting is more frequently observed in WTaCrV, the
alloy shows better resistance to primary irradiation damage compared to pure W. Apart from cascade splitting, analysis of interstitials shows that Cr and to lesser extent V, being lighter and smaller elements, accommodate the damage in form of point defects, contributing to the mitigation of formation of the dislocation loops.
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All authors Mark Fedorov, Francisco Javier Dominguez-Gutierrez, Damian Kalita, Łukasz Kurpaska
Soft Condensed Matter
Meso-scale modeling of cohesive cavitation in polymer networks
Saleh Assadi, Zachary T. White, Fay Salmon et al. (+6 more)
Cavitation influences the failure of elastomers and soft adhesives, but connecting its microscopic initiation to subsequent cavity growth remains challenging. Here, we develop a discrete mesoscale framework that combines finitely extensible, breakable strands with local van der Waals interactions to examine how cohesion and network heterogeneity transform distributed dilation into localized damage. In the simulations, local cohesive instability produces a network-scale precursor whose subsequent expansion is coupled to strand stretching and rupture. Cohesive strength and intrinsic defect size govern the critical hydrostatic tension, while cohesion also controls the number and spatial distribution of cavities. Under confined loading, decreasing the layer thickness promotes multiple cavities and distributed strand rupture, extending the load-bearing response and increasing the critical work density of rupture. An energetic interpretation based on the thickness dependence of the crack-driving force connects these observations to competition between additional cavity nucleation and propagation of existing damage. The results link local cohesive instability to the collective
evolution of cavities and rupture in disordered
polymer networks.
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All authors Saleh Assadi, Zachary T. White, Fay Salmon, Nitin Hansoge, Zhuonan Liu, Victor Crespo-Cuevas, Jason Clapper, Nikolaos Bouklas, Franck J. Vernerey
Astrophysics of Galaxies
Untangling Similarities and Differences in Star Formation Histories Across Cosmological Simulations
Alicia M. Savelli, Matthew A. Kustec, Joshua S. Speagle et al. (+5 more)
How
galaxies assemble depends on processes ranging from small-scale baryonic physics to large-scale cosmological assembly, which are difficult to disentangle with observations alone. Using $\sim$63,000 simulated
galaxies from seven cosmological simulations spanning hydrodynamical, semi-analytic, and semi-empirical models, we explore how specific
star formation histories (sSFHs) vary across modelling assumptions. Using non-linear dimensionality reduction (UMAP), we find that sSFH shape variation organizes along a few smooth axes in a 2D
embedding, broadly corresponding to (1) peak timing, (2) peak sharpness, and (3) subsequent quenching rate. We identify sSFH shapes that many simulations share ("common"), well described to first order by dark matter
halo assembly, and a few tied to individual simulations ("unique"), which likely reflect subgrid and parametrization choices such as merger-triggered burst prescriptions. A notable exception is a common population of rapidly quenched
galaxies found across most simulations, likely driven by e.g., active galactic
nucleus (AGN) feedback, that
halo assembly alone cannot reproduce. The origin of the most distinctive unique shape, an Illustris-dominated history with an early peak and slow decline, remains unclear, but we test the effects of short-term variability. With a multi-objective auto-encoder neural network, we recover the simulation that a given sSFH is drawn from with $\sim$95% out-of-sample accuracy; ablation tests indicate this information is embedded in long-timescale sSFH morphology rather than short-term variability. These results provide avenues for theoretical and observational follow-up connecting
star formation histories to subgrid physical models.
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All authors Alicia M. Savelli, Matthew A. Kustec, Joshua S. Speagle, Kartheik G. Iyer, Eshal Ahmed, Zehao Peng, Norman Murray, Cissy Kuang
Fluid Dynamics
Preferential concentration in a periodically forced particle-laden turbulent planar jet
Mohammad Ahmad, Pierre Bragança, Christophe Cuvier et al. (+1 more)
Periodic forcing is common in particle-laden jets, yet its influence on
turbulence and inertial-particle clustering remains poorly understood. We investigate a turbulent planar jet at two Reynolds numbers, approximately 4950 and 9900 based on nozzle height, subjected to sinusoidal forcing at a frequency three orders of magnitude below the preferred jet instability. Hot-wire anemometry and high-speed particle imaging characterise the carrier
turbulence, while Voronoi tessellations quantify preferential concentration of dilute inertial droplets. Despite its low frequency and moderate amplitude, forcing substantially modifies
turbulence while leaving the mean-flow development nearly unchanged. The integral scale decreases by up to $40\%$, while forced and unforced jets retain the same time-averaged relationship between the dimensionless dissipation coefficient and Taylor-scale Reynolds number. Within the forcing cycle, velocity fluctuations and the Taylor microscale vary approximately in opposite phase, keeping the Taylor-scale Reynolds number within $\pm10\%$ of its cycle mean despite substantial variations in dissipation and Kolmogorov time scale. Particle clustering is even more sensitive, with forcing increasing mean preferential concentration and producing phase-dependent variations of $21$–$49\%$ of the cycle mean. Clustering peaks when the Kolmogorov time scale is largest, corresponding to the smallest particle Stokes number. Thus, markedly different clustering states occur at similar instantaneous Taylor-scale Reynolds numbers. These findings demonstrate that weak temporal modulation can control particle organisation without substantially altering the mean transporting flow.
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All authors Mohammad Ahmad, Pierre Bragança, Christophe Cuvier, Martin Obligado
Materials Science
Can Universal Machine-Learning Interatomic Potentials Capture Small Polarons? A Geometry-Based Benchmark in Transition-Metal Oxides
Vladislav Korostelev, Pjotrs Žguns and Konstantin Klyukin
Small polarons, formed when excess electrons become localized through
lattice distortions, play a critical role in charge transport, catalysis, and degradation processes in transition-metal (TM) oxides. Whether universal machine-learning interatomic potentials (uMLIPs), which lack explicit electronic degrees of freedom, can describe them remains unclear. Here, we investigate H-induced electron localization across a range of TM oxides using a
geometric descriptor based on TM-O bond-length expansion (Z-score) to identify polaronic distortions. We find that uMLIPs exhibit varying degrees of electron localization, from delocalized states to metastable small polarons, with their behavior strongly dependent on the training data and treatment of electronic correlations. In particular, the absence of Hubbard U corrections for specific TM cations in the training data leads to electron delocalization, in contrast to DFT+U predictions. Although some uMLIPs reproduce polaron hopping barriers during coupled
proton-polaron transfer, all of them fail to stabilize spatially separated polaron-donor configurations, instead favoring localization near the H dopant.
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High Energy Physics (Phenomenology)
Pallavi Bhardwaj and Michael Spannowsky
Lorentz
symmetry and the three-prong structure of hadronic top decays provide physical guidance for designing compact
quantum jet taggers. We introduce QGrAT (
Quantum Grade-Aware
Transformer), a
quantum transformer that incorporates these structures into its interactions between constituent
qubits.
Geometric features constructed from the constituent four-momenta are organised by the grades of the spacetime Clifford
algebra $C\ell(1,3)$, and their grade-specific inner products determine the pairwise
attention couplings. For fixed constituents and co-transforming reference vectors, these couplings are Lorentz invariant, although the component-wise input encoding makes the complete classifier frame dependent. An auxiliary
qubit introduces an explicit three-particle interaction through products of pairwise Minkowski inner products, while a trainable in-
circuit readout converts the resulting
quantum state into a classification score. We evaluate the architecture in state-vector simulation on the Top Tagging
benchmarks. With ten constituents per jet, the configuration using grades $0\text{-}3$ and the three-particle ancilla requires twelve
qubits and $144$ trainable parameters, reaching AUC $0.944 \pm 0.002$ and background rejection $1/\varepsilon_B = 35.7 \pm 2.4\ (96.8 \pm 7.7)$ at signal efficiency $\varepsilon_S = 0.50\ (0.30)$. This performance is competitive with the L-GATr-Slim baseline at matched constituent and parameter budgets. Adding the three-particle ancilla raises background rejection at $50\%$ signal efficiency from $19.9$ to $35.7$, whereas extending the representation to the tested grade-$4$ feature gives no consistent improvement. The study establishes a framework for incorporating spacetime geometry into
quantum attention and identifies explicit three-particle correlations as the principal source of improved background rejection among the architectural variations tested.
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Disordered Systems and Neural Networks · Cross-listed from cs.LG
On the Statistical Mechanics of Attention
Jerry Yao-Chieh Hu, Yu-An Chen, Maojiang Su et al. (+1 more)
We revisit the statistical mechanics of
Transformer attention via modern Hopfield models. We present a free-energy formalism to characterize parameter regimes and critical thresholds for robust
attention inference. The resulting free-energy landscape incorporates randomness in query states and
attention weights.
Attention then emerges as the equation of motion of the corresponding statistical-mechanical system (i.e., modern Hopfield model) through the standard free-energy minimization principle. This allows us to identify first-order phase transitions in
attention between glassy and robust-inference phases. We further extend to attentions with
stochastic queries and keys. Together, our results provide a rigorous statistical-mechanics framework for characterizing phase structure and inference reliability across a family of
Transformer attention mechanisms.
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All authors Jerry Yao-Chieh Hu, Yu-An Chen, Maojiang Su, Han Liu
High Energy Physics (Phenomenology)
Non-accumulation of background-enhanced neutrino forces in proto-neutron stars
Himanshu Bora, Anupam Deka and Debajyoti Dutta
In a
neutrino background, the
vacuum two-
neutrino exchange potential $V \propto G_F^2 /r^5$ acts as a much longer-ranged interaction, scaling as $V\sim1/r$ for a directional background. A proto-
neutron star (PNS) hosts one of the densest astrophysical
neutrino environments known, and naturally provides a setting in which to test whether this pairwise enhancement produces a macroscopic Hartree contribution. We show that this does not happen. In the
spin-independent sector, averaging over pair orientations projects the background onto its angular monopole. The bulk Hartree contribution then saturates instead of growing with system size. We also find that the
spin-dependent parity-conserving and parity-violating terms do not generate macroscopic growth under the PNS mean-field conditions considered here. Thus, although the pair potential can be strongly enhanced, the resulting bulk interaction remains very small. The suppression comes from the angular and oscillatory structure of the kernel, not from screening. Within the Standard Model mechanism considered here, the effect is not important for the PNS equation of state or for events like
pulsar kicks.
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Soft Condensed Matter
Machine-learned topological transport of magnetic colloids
Sebastian Wohlrab, Aneena Rinu Perayil, Piotr Kuświk et al. (+6 more)
By modulating the orientation of a uniform
magnetic field it is possible to transport
magnetic microparticles above
magnetic patterns. In periodic patterns, driving control loops that wind around special orientations, which are dictated by the
symmetry of the pattern, induce transport by one unit
cell. The transport is topologically protected with trajectories controlled by the winding numbers of the control loop around the special orientations. In non-periodic patterns, the special orientations are position dependent, precluding a global characterization of the transport using a small set of winding numbers. We use here a reinforcement learning
agent trained with Brownian dynamics simulation data that uses the local environment of the
magnetic pattern to decide an action over the control loop. The
agent autonomously discovers topological transport protocols directly from the particle response without prior characterization of the
magnetic potential landscape. An
agent trained solely on a complex non-periodic pattern directly generalizes to completely unseen periodic, quasicrystalline, and disordered substrates. Moreover, the
agent dynamically adjusts the control loop to transport particles across
lattice defects and to counterbalance external drift forces that would cause static topological loops to fail. By adding a pathfinding
algorithm to the model, we additionally achieve simultaneous, independent transport of multiple identical colloids along different on demand trajectories. We demonstrate that the control loops can be directly transferred to an experimental setup to successfully drive
magnetic microparticles across a non-uniform
magnetic thin film.
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All authors Sebastian Wohlrab, Aneena Rinu Perayil, Piotr Kuświk, Maciej Urbaniak, Feliks Stobiecki, Arne J. Vereijken, Arno Ehresmann, Thomas M. Fischer, Daniel de las Heras
Astrophysics of Galaxies
Intermittency in the Multiphase ISM — I. Extreme Density, Velocity, and Magnetic Fluctuations
Yue Hu
Intermittency is a fundamental property of astrophysical
turbulence because it concentrates strong gradients, dissipation, and transport into rare, localized structures. In the multiphase interstellar medium (ISM), turbulent driving is especially important because the balance between compressive and solenoidal motions can regulate how extreme fluctuations are distributed among thermal phases. Yet conventional increment statistics quantify intermittency without identifying the structures that host it. We analyze three matched ideal-MHD simulations of a thermally multiphase neutral medium that differ only in the compressive fraction of the driving. Density, velocity, and
magnetic-field increments are non-Gaussian in every thermal phase. Increasing compressive driving redistributes density and
magnetic fluctuations preferentially into the cold gas rather than uniformly enhancing them across phases. We identify the structures associated with extreme increments using local, scale-matched diagnostics of compression, thermal gradients, vorticity, strain,
magnetic curl, and
magnetic tension. Extreme
magnetic increments preferentially occur where
magnetic curl and
magnetic tension are simultaneously enhanced, more strongly than extreme velocity increments are associated with their kinematic hosts. Extreme velocity increments show comparable enrichment in vorticity and strain, whereas extreme density increments preferentially trace converging flows and thermal gradients only in the unstable medium. These associations weaken beyond a phase-dependent coherence scale. Our results show that turbulent driving controls how intermittency is partitioned among thermal phases, while distinct physical structures host extreme density, velocity, and
magnetic fluctuations.
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