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Physics

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Wednesday 26 August

Astrophysics of Galaxies

Evidence for the transformation from lenticular to spiral galaxies

Mengkui Zhou, Huiyuan Wang, Ran Li et al. (+8 more)

It is widely accepted that late-type galaxies, such as spirals, evolve into early-type systems, including elliptical and lenticular galaxies, through galaxy mergers and violent disk instability processes. Throughout this morphological transformation, star formation is typically suppressed by quenching mechanisms whose detailed nature remains the subject of active investigation. Here, we present compelling evidence for an evolutionary pathway that proceeds in the reverse direction. Using the integral field unit observations, we identify a population of spiral galaxies hosting quenched central cores (QCCs). These galaxies exhibit bimodal distributions in both their stellar population properties and their dynamical properties, along with sharp changes in radial gradients near the QCC boundary. These results indicate that the QCCs and the surrounding outer disks formed at distinct cosmic epochs and through different physical processes. Remarkably, QCCs closely resemble quiescent early-type galaxies, particularly lenticular galaxies, in their mass-size and mass-velocity dispersion scaling relations, as well as in their stellar population demographics and internal kinematics. These findings provide strong support for a rejuvenation scenario in which spiral disks are reassembled around pre-existing quiescent lenticular or early-type systems. Moreover, we show that such rejuvenation, accompanied by a reverse morphological transformation from early- to late-type appearance, is quite common. This indicates that quenching in galaxies is not invariably a terminal state and can be reversed under appropriate conditions.
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All authors Mengkui Zhou, Huiyuan Wang, Ran Li, Yangyao Chen, Hui Hong, Houjun Mo, Yu Rong, Enci Wang, Huiling liu, Zhicheng He, Ziwen Zhang

Astrophysics of Galaxies

Stellar mass growth in COSMOS-Web: a mass-complete main sequence to z ~ 8 and its consistency with GSMF evolution

M. P. Koprowski, K. Lisiecki, P. Sawant et al. (+1 more)

The star-forming main sequence (MS) links the instantaneous star-formation rate of galaxies to their stellar-mass growth and therefore to the evolution of the galaxy stellar mass function (GSMF). We determine a mass-complete MS in COSMOS-Web out to z=8 and test whether its mass and redshift dependence is consistent with the observed evolution of the GSMF. We stacked 251,462 star-forming galaxies in Herschel and JCMT maps and corrected the far-infrared fluxes for blending using forward-modeled maps. We combined the resulting infrared luminosities with the unobscured ultraviolet emission to derive total star-formation rates and fitted a redshift-dependent MS. We independently measured the quiescent fraction and evolved the observed z=8 COSMOS-Web GSMF forward within a continuity-equation framework including stellar-mass return, suppression of in-situ growth by the quiescent fraction, and mergers. The MS is well described by a power law at low masses with a redshift-dependent turnover toward high masses. We measure a low-mass slope of gamma=1.215+/-0.028, implying a mildly increasing specific star-formation rate with stellar mass. The GSMF evolved using this relation follows the observed progressive flattening of the low-mass end substantially better than the literature MS prescriptions considered here. Mergers change the low-mass number densities by <=0.2 dex by z~0.65 and have little effect on the slope. Small differences in MS normalization also accumulate strongly, producing large differences in the evolved GSMF after several Gyr. The observed GSMF evolution provides an independent integral test of the MS. Our results favor a mildly super-linear low-mass MS and show that both its slope and normalization must be measured accurately to reproduce the buildup of the galaxy stellar-mass distribution.
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All authors M. P. Koprowski, K. Lisiecki, P. Sawant, J. V. Wijesekera

Chemical Physics

Benchmark of Multi-Channel Dyson Equation and Algebraic Diagrammatic Construction Methods for molecules

Mike Keizer, Stefano Paggi, J. Arjan Berger et al. (+2 more)

The Dyson-algebraic diagrammatic construction (ADC) and the multi-channel Dyson equation (MCDE) formalisms explicitly leverage multi-particle channels to formulate correlated theories of the single-particle Green's function that produce positive semi-definite spectral functions by construction. While the MCDE is strictly rooted in the Dyson formalism, most ADC calculations are performed in the non-Dyson (nD) framework that decouples electron attachment and detachment sectors. We benchmark the Dyson-ADC(2)-X [that is equivalent to the (3,1)-MCDE] and ADC(3) approximations on a set of 58 ionization potentials of 23 small molecules for which near-full configuration interaction reference data exist. Comparison of Dyson- to nD-ADC(3) reveals deviations of the order of 0.1 eV between both methods, calling into question the reliability of the nD approximation. We show that Dyson-ADC gives similar accuracy for first IPs as for semi-valence and semi-core transitions. Finally, we also benchmark the screened (3,1)-MCDE that screens all ladder interactions, and show that it improves over its unscreened counterpart.
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All authors Mike Keizer, Stefano Paggi, J. Arjan Berger, Pina Romaniello, Arno Förster

Geophysics

GeoFormer: Geometry-Aware Transformer and its application to 5D First-Arrival Picking

Tianxiang Gao and Jianwei Ma

We propose GeoFormer, a Geometry-Aware Transformer architecture specifically designed for prestack seismic data. Unlike Vision Transformer, whose tokens are extracted from 2D patches and primarily encode visual patterns, GeoFormer is designed for prestack seismic data by explicitly incorporating acquisition geometry. Each seismic trace is represented by a 5D unit consisting of the waveform and four source-receiver coordinates, from which two geometric attributes are derived: offset and relative elevation, where relative elevation is the receiver elevation minus the source elevation. GeoFormer therefore performs trace-level tokenization, where each token combines the waveform with these geometric attributes. To exploit these geometric attributes, GeoFormer introduces three geometry injection mechanisms operating at different levels of the Transformer pipeline. At the token level, GeomMLP replaces the classification token with a per-trace geometric representation derived from offset and elevation. At the normalization level, GeomAdaLN replaces uniform layer normalization with geometry-conditioned feature modulation. At the attention level, GeomAttnBias injects a parameter-free physical prior that geometrically proximate traces should attend more to each other. We validate GeoFormer on first-arrival picking, a representative seismic processing task that relies heavily on acquisition geometry. Experiments on four field datasets demonstrate that GeoFormer outperforms Vision Transformer and two task-specific baselines. Crucially, GeoFormer maintains robust picking accuracy under strong noise because its trace-level tokens encode geometric attributes that provide a physical prior independent of waveform quality. Ablation studies confirm that GeomMLP, GeomAdaLN, and GeomAttnBias each contribute to GeoFormer's picking accuracy.
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Strongly Correlated Electrons

Phase calibration of quantum oscillations in the magnetostrictive coefficient using the topological antiferromagnet YbMnBi$_2$

Qin Deng, Long Zhang, Zeyu Li et al. (+6 more)

The Berry phase accumulated along a cyclotron orbit encodes important information about electronic band topology and is commonly inferred from the phase of quantum oscillations. Measurements of the ac magnetostrictive coefficient have recently emerged as a sensitive thermodynamic probe of quantum oscillations, but the phase offset has not been experimentally calibrated. Here, using the topological antiferromagnet YbMnBi$_2$, we calibrate this offset by directly comparing quantum oscillations in magnetization with those in the ac magnetostrictive coefficient. Measurements of both responses on the same single crystal reveal a single fundamental frequency of approximately 160 T in fields up to 14 T, enabling a direct phase comparison free from ambiguities associated with multiple frequencies. We observe an approximately $\pi/2$ relative phase shift between the two oscillatory responses, consistent with the Maxwell relation linking the magnetostrictive coefficient to the stress derivative of magnetization. Our results establish the appropriate phase needed to extract cyclotron-orbit phase information from quantum oscillations in the ac magnetostrictive coefficient.
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All authors Qin Deng, Long Zhang, Zeyu Li, Ying Zhu, Shuai Wu, Yan Liu, Aifeng Wang, Yu Pan, Yisheng Chai

Computational Physics

A unified gas-kinetic wave-particle method for multiscale gas-mixture flow with an elementary chemical reaction

Junzhe Cao, Yufeng Wei, Wenpei Long et al. (+2 more)

Hypersonic flows in the near space often couple continuum-rarefied multiscale effect with finite-rate chemistry. This paper extends the UGKWP method to multiscale gas mixture flows with a single elementary reaction. In the UGKWP method, hydrodynamic waves are employed to describe near-equilibrium distribution functions, and numerical particles are used for the evolution of nonequilibrium ones. The adaptive conversion between waves and particles, guided by the characteristic integral solution, together with the introduction of dt into the flux as an observation scale, has enabled the UGKWP method to succeed in many multiscale problems involving complex physics. In this work, rather than relying on a comprehensive reactive kinetic model for the entire distribution function, chemical source terms are first evaluated at the macroscopic level and then incorporated into the wave-particle update, while free-transport particles are kept chemically inactive in the monatomic setting considered here. This approach leverages the modeling advantages of wave-particle decoupling, facilitating extension to more complex chemical reactions. Moreover, an approximate extension of an advanced multispecies kinetic model is developed in this work for multispecies effect with species number larger than two. The present UGKWP method is assessed for the Zeldovich-type reaction O2+N=NO+O through hypersonic cylinder flows over a wide Knudsen number range, covering chemically inert, forward exothermic, forward endothermic and dE=0 conditions, and through shock structures with hot upstream/downstream equilibrium states. Agreement with DSMC is obtained for gas mixture flow fields, species mole fractions and wall quantities. A three-dimensional side jet flow over a blunt cone is further simulated to demonstrate the three-dimensional capability of the present code.
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All authors Junzhe Cao, Yufeng Wei, Wenpei Long, Chengwen Zhong, Kun Xu

Quantum Physics

Quantum motility-induced phase separation

Laurin Brunner, Ricard Alert, Reyhaneh Khasseh et al. (+1 more)

Motility-induced phase separation (MIPS) describes a central clustering phenomenon in active matter systems where particles spontaneously separate into dense and dilute phases even in the absence of interparticle attractive forces. Recent theoretical and experimental efforts have taken the first steps to extend active matter concepts to the quantum level. However, whether a genuine quantum analog of MIPS exists and how quantum coherence would compete or cooperate with the dissipative self-propulsion has remained open so far. Here, we provide evidence that quantum MIPS can occur in a model of active hard-core bosons in one dimension. Our model yields superlinear number fluctuations characteristic of MIPS, leading to microphase separation with large but finite cluster size. Adding nearest-neighbor repulsive interactions, we find numerical evidence for restoring genuine phase separation with a divergent correlation length. Crucially, the clustered steady states maintain a long-distance quantum coherence, revealing a genuinely quantum feature with no classical counterpart. These results provide a foundation for exploring quantum MIPS and suggest that the coherence-activity interplay can generate new types of nonequilibrium quantum states.
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All authors Laurin Brunner, Ricard Alert, Reyhaneh Khasseh, Markus Heyl

Exactly Solvable and Integrable Systems

Sato-theoretic construction of the anti-self-dual Yang-Mills hierarchy and the Ward conjecture

Shangshuai Li and Da-jun Zhang

We develop the Sato-theoretic dressing framework for the anti-self-dual Yang-Mills (ASDYM) hierarchy based on a normalized Riemann-Hilbert decomposition. A four-sector expansion of the generating function yields a bi-infinite matrix array of relative coordinates, extending the affine coordinates on the big cell of the Sato Grassmannian. We derive the Sato-Wilson equations, continuous coordinate flows, and their discrete analogues. Several classical integrable hierarchies are recovered under dimensional reduction constraints, with their nonlinear variables identified as specific relative coordinates.
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Quantum Physics

Phase-sensitive cascade quantum amplifier with nearly noiseless operation

Ilari Lilja, Ekaterina Mukhanova, Michael Perelshtein et al. (+5 more)

Phase-sensitive parametric devices enable quadrature-selective amplification with the potential for sub-quantum-limited noise performance. In this work, we investigate the operation of a SQUID-based Josephson Parametric Amplifier (JPA), comparing its performance in the phase-preserving and phase-sensitive regimes. The device, fabricated using VTT SWAPS technology, is driven in a three-wave mixing configuration and characterized in a reflection-based measurement setup at millikelvin temperatures. To directly probe the noise performance at low JPA gains, we employ a cascaded amplification scheme in which a Traveling-Wave Parametric Amplifier (TWPA) provides low-noise pre-amplification of the JPA output. In a phase-preserving operation, the JPA exhibits near-quantum-limited performance with a system noise temperature of $351\pm53$ mK at 6 GHz. In contrast, phase-sensitive operation yields a minimum system noise temperature of $94\pm12$ mK, well below the standard quantum limit of 288 mK. Our results demonstrate that a JPA-TWPA amplifier cascade opens the door to direct, high-fidelity probing of quantum devices without the need for background noise subtraction.
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All authors Ilari Lilja, Ekaterina Mukhanova, Michael Perelshtein, Kirill Petrovnin, Stanislav Khaldeev, Visa Vesterinen, Gheorghe Sorin Paraoanu, Pertti Hakonen

Materials Science

Nuclearity of Copper Clusters on hBN/SiC Heterostructure Modulates Molecular Adsorption

Reza Khakpour, Arsalan Hashemi, Xiaoya Chang et al. (+3 more)

Defect engineering can transform inert two-dimensional (2D) materials into chemically active and electronically tunable platforms by creating anchoring sites for metal atoms and clusters. Nevertheless, precise control over the formation, thermodynamic and kinetic stability, electronic structure, and chemical reactivity of metal species confined at these defect sites remains a challenge. Here, we use density functional theory (DFT) calculations assisted by machine-learning molecular dynamics (MLMD) simulations to elucidate the stability, electronic structure, and reactivity of Cu clusters anchored at boron vacancies (VB) in hBN/SiC heterostructures. Systematic variation of the Cu-to-vacancy ratio reveals a transition from isolated Cu atoms to multiatom Cu clusters at VB sites, with cluster growth reshaping the stability, electronic structure, and surface reactivity. Our results show that a single VB defect can be passivated by three Cu atoms, which compensate the local charge deficiency and stabilize the defect through Cu-N coordination. Capturing further Cu introduces localized midgap states that could influence the reactivity of the Cu-decorated defect sites. We probe the response of the Cu-decorated surface to chemically relevant gases CO, H2, O2, N2, H2S, and CO2, revealing implications for surface reactivity and stability. The calculations show pronounced cluster-size-dependent reactivity of Cu clusters at VB sites, with CO forming strong Cu-C bonds and O2 undergoing enhanced adsorption and molecular activation. Overall, this work identifies defect-engineered hBN/SiC as a versatile 2D platform for stabilizing Cu clusters and tuning gas-surface reactivity. By correlating Cu nuclearity at VB sites with electronic structure, molecular activation, and environmental robustness, our findings provide design guidelines for nuclearity-dependent metal functionalization of 2D heterostructures.
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All authors Reza Khakpour, Arsalan Hashemi, Xiaoya Chang, Nima Ghafari Cherati, Mikko Karttunen, Tapio Ala-Nissila

Statistical Mechanics

Exact chemo–thermal Metropolis Brownian engine: chemical leverage, temperature-neutral stall, power optimization, and multicyclic dissipation

Mesfin Taye

We develop an exactly solvable chemo–thermal extension of the three-state Metropolis Brownian heat engine. The particle moves through the periodic energy sequence $0\to E\to 2E\to0$, performs mechanical work against a load $f$ on every forward step, interacts with two cold links and one hot link, and consumes one fuel molecule of free-energy drop $\muu$ on the hot transition. Local detailed balance gives an exact cycle affinity \begin{equation*} \mathcal A=E\left(\Tc^{-1}-\Th^{-1}\right)+\muu/\Th-f\left(2/\Tc+1/\Th\right), \end{equation*} and the full stationary probabilities and current are obtained without linear-response, weak-driving, or high-barrier approximations. Several results follow. First, the exact stall force is \begin{equation*} \fs=\frac{E(\Th-\Tc)+\Tc\muu}{2\Th+\Tc}. \end{equation*} Second, there is a temperature-neutral chemical compensation point $\muu_*=3E/2$ at which $\fs=E/2$ for every $\Th>\Tc$ and the hot and cold heats both vanish at reversible stall. Third, in both Metropolis branches the stationary current is a strictly increasing function of $\muu$ at fixed mechanical parameters, but approac
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High Energy Physics (Phenomenology)

A Comprehensive Analysis of the R2HDM Vacuum Evolution and the Induced GW and Collider Phenomenology

Lisa Biermann, Christoph Borschensky, Rafael Boto et al. (+3 more)

Extended Higgs sectors beyond the Standard Model (BSM) allow to dynamically generate the observed baryon asymmetry of the Universe through electroweak baryogenesis and thereby solve one of the most prominent open problems of the SM. The strong first-order phase transitions (PTs), required to preserve the generated asymmetry in the electroweak vacuum, source gravitational waves (GW) that can be tested at future experiments like LISA. Gravitational waves hence provide the exciting possibility to probe BSM physics through cosmological processes. In order to be able to eventually pin down the specific underlying physics, a good understanding of the evolution of the vacuum of the model under investigation is indispensable as well as of the uncertainties that are involved in the derivation of the GW spectrum. We use our code BSMPTv3 that allows to reliably derive the finite temperature vacuum structure of extended Higgs sectors with multiple vacuum directions and calculates the GW spectrum of the found (multiple) strong first-order PTs, and we apply it to the real, i.e. CP-conserving, 2-Higgs-Doublet Model. Taking into account all relevant theoretical and experimental constraints, we perform a thorough analysis of its vacuum evolution, the related collider and GW phenomenology and complement it by an uncertainty discussion.
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All authors Lisa Biermann, Christoph Borschensky, Rafael Boto, Margarete Mühlleitner, Rui Santos, Joao Viana

Cosmology and Nongalactic Astrophysics

Distinguishing cold and self-interacting dark matter through topological analysis

Adrian Szpilfidel, Clotilde Laigle, Pierre Boldrini et al. (+2 more)

Alternative dark matter (DM) models have emerged to solve the challenges faced by the predictions of collisionless cold dark matter (CDM) on galactic scales ($\lesssim 1$ Mpc). However, disentangling alternative models from CDM is difficult on such small scales because of the degeneracy with baryonic physics. It is therefore necessary to use DM probes that are not affected by baryons, e.g. that stand on intermediate scales, larger than galactic while remaining smaller than the scale at which the models converge to CDM. For the first time, we distinguish self-interacting DM (SIDM) from CDM using the genus statistic, a metric that characterises the topology of the density field. We carried out the analysis on the Darkium DM-only cosmological simulations, using one CDM model and four SIDM models with cross-sections of various amplitudes and velocity dependencies. We computed the genus on selected 3-virial radius wide regions centred around halos, for few hundred halos with masses ranging from $10^{12}$ to $10^{14}$ M$_\odot/h$ over redshifts $z=0$ to $z=2$. We also explored a more observation-like configuration, where the DM density field is traced only from the halo distribution in thick 2D projection since in principle redshift errors hinder a 3D reconstruction of the density field. We find that the density field is systematically clumpier in CDM than in SIDM models up to $0.05~\mathrm{Mpc}/h$, for halos of masses larger than $10^{12}$ M$_\odot/h$ at $z=0$. These predictions show that the genus of the density field is sensitive to DM self-interactions, suggesting that topological analysis could provide a valuable probe for distinguishing SIDM from CDM in observed halo distributions.
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All authors Adrian Szpilfidel, Clotilde Laigle, Pierre Boldrini, Moritz S. Fischer, Dmitri Pogosyan

Disordered Systems and Neural Networks · Cross-listed from q-bio.QM

Propensity Straight-Through Gradients for Discrete Stochastic Systems

Jose M. G. Vilar and Leonor Saiz

We introduce the propensity straight-through (PST) estimator for gradient-based learning through exact simulations of continuous-time Markov chains (CTMCs). These models describe discrete stochastic dynamics across physics, chemistry, and biology, but their categorical event choices prevent ordinary differentiation. PST preserves exact forward trajectories and differentiates, in the backward pass, the normalized reaction propensities the simulator already computes. The affine state update makes this rule exact for the one-step conditional-mean sensitivity. We derive the per-step discrepancy for one-step sensitivities composed along nonlinear trajectories in closed form, show that it vanishes for affine downstream dependence, and bound it quadratically in the stoichiometric jump size. Across reversible dimerization, a genetic oscillator, a 50-task repressilator suite, and experimental patch-clamp recordings, PST recovers parameters to within 0.06-1.7% and converges 2.4-3.0-fold faster than the Gumbel-Softmax straight-through estimator at matched computational cost. At deep-learning scale, PST trains all 203,796 parameters of a stochastic reaction network using exact discrete events from initialization. By differentiating an exact conditional mean, PST eliminates reaction-selection temperature tuning and provides a scalable route to learning through exact stochastic dynamics.
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Soft Condensed Matter

Closed-form hard-sphere thermodynamics under nanoscale confinement: from equations of state to unmixing forces

Jose M. G. Vilar and Leonor Saiz

Equations of state accurately describe hard-sphere thermodynamics but are generally considered to fail under nanoscale confinement. We show that this failure is geometric rather than thermodynamic: a closed-form, parameter-free mapping from apparent to effective packing fraction restores the accuracy of the Carnahan-Starling equation of state and, with it, the entire analytical thermodynamic framework, including free energies, wall pressures, chemical potentials, and the large-cavity surface response. Applied to overlapping anchored hard-sphere droplets, a geometry inherent to biomolecular force generation, it yields unmixing free energies and full distance-dependent force profiles in quantitative agreement with simulations from the dilute regime to above the bulk freezing transition.
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Materials Science

Magnetic-configuration design for reliable Heisenberg exchange parameters

Ben Li, Stephan von Malottki and Gian-Marco Rignanese

The determination of magnetic exchange interactions is essential for the quantitative description and predictive modeling of magnetic materials. In this work, we present a neighbor-shell-based screening method for selecting magnetic configurations suitable for extracting Heisenberg exchange parameters beyond nearest-neighbor from density functional theory (DFT) calculations. Using only the structure, the proposed approach identifies the linear independence of neighbor-shell contributions before any first-principles calculations instead of relying on trial-and-error generation of magnetic configurations. We apply the proposed approach to two representative classes of magnetic configurations: random spin states and spin spirals, and validate its predictions against direct DFT fitting for Fe and MnF$_2$. We show that only parameters obtained when all relevant neighbor-shell contributions are linearly independent remain transferable to other magnetic configurations. The proposed method provides practical guidance for selecting magnetic configurations for reliable exchange-parameter extraction and may also benefit other neighbor-shell-based models.
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Nuclear Theory

Directional correlations in nuclear charge-radius model residuals enable extrapolation with calibrated uncertainties

Debodyuti Kar, Soumya Bagchi, Timo Dickel et al. (+1 more)

We identify a pronounced directional anisotropy in the residuals between measured nuclear charge radii and two structurally distinct global models: the phenomenological Weizsäcker–Skyrme formula (WS*) and the microscopic Hartree–Fock–Bogoliubov model (HFB-25). In both cases, the residuals remain correlated over several neutron steps along isotopic chains but decorrelate almost completely after a single proton step along isotonic chains. This common pattern, reinforced by a strong correlation between the two residual fields ($r\simeq0.73$), points to a shared deficiency of both global descriptions rather than a model-specific artefact. Motivated by this geometry, we introduce ARCUS (Anisotropic Residual Calibration with Uncertainty Scaling), which applies an anisotropic kernel-regression correction with empirically calibrated prediction intervals. In out-of-fold cross-validation, ARCUS reduces the root-mean-square errors of both WS* and HFB-25 by approximately a factor of two. On an independent, temporally blind test set of 129 nuclei, its prediction intervals retain coverage close to nominal under extrapolation. An isotropic kernel matched to the same cross-validation coverage instead substantially overestimates uncertainties on the blind set, showing that reliable calibration transfer depends on encoding the directional residual structure. In regions with anomalous structure, such as around $^{52}$Ca, ARCUS keeps its prediction intervals wide enough to cover the increased errors, rather than yielding overconfident point predictions. We also extend these calibrated predictions to 1008 unmeasured nuclei near known isotopic chains, ranked by uncertainty to support the future charge-radius measurements.
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All authors Debodyuti Kar, Soumya Bagchi, Timo Dickel, Rituparna Kanungo

High Energy Astrophysical Phenomena

Ultraluminous X-ray sources in the first eROSITA survey I. Candidate catalogs

P. Weber, T. P. Roberts, S. Hämmerich et al. (+28 more)

Ultraluminous X-ray sources (ULXs) are luminous non-nuclear X-ray point sources embedded in galaxies. Their luminosities exceeding 10^39 erg/s potentially require sub-Eddington accretion by objects with masses from ~10^2$M_{\odot}$ to ~10^4$M_{\odot}$ or supercritical accretion beyond the Eddington limit by stellar mass black holes or neutron stars. We identified ULXs by searching for X-ray counterparts in the ~10^5 galaxies of the HECATE catalog in the footprint of the first eROSITA all-sky survey, while excluding nuclear regions to avoid the selection of active galactic nuclei (AGN). We characterized the completeness of the sample and its contamination by unidentified AGN and determined the influence of source confusion. The catalog is unaffected by X-ray selection biases. We removed known contaminants such as supernovae, stars, and AGN, and manually vetted all candidates to further remove contaminants. We derived the X-ray selection function and fraction of unidentified AGN interlopers using a simulation with subsequent source detection. We present two samples of ULX candidates. The main sample consists of 90 sources with highly confident X-ray detections, 53 of which are identified for the first time. This sample is complete to a distance of ~7Mpc, contains at most 29% of unknown background AGN, and is mostly unaffected by source confusion. Several candidates are newly identified even though their locations have been observed by other instruments before, and some previously reported candidates we expected to identify are absent from our sample, demonstrating the transient behavior of ULXs. Based on our list of less confident detections, we also provide an extended catalog of 260 sources identified as potential candidates for further ULX identifications. Of these, 245 are identified as potential candidates for the first time. (Abridged)
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All authors P. Weber, T. P. Roberts, S. Hämmerich, E. Kyritsis, A. Zezas, M. G. F. Mayer, A. Zainab, I. Kreykenbohm, A. Merloni, M. Sasaki, A. Schwope, M. Middleton, A. Basu-Zych, A. Hornschemeier, N. Vulic, M. Salvato, N. Webb, H. Tranin, N. Schettino, C. Kirsch, S. Saeedi, F. Zangrandi, M. Lorenz, L. Dauner, T. Dauser, F. Haberl, C. Maitra, Z. Igo, A. Santangelo, L. Ducci, J. Wilms

Astrophysics of Galaxies

Revealing Galactic dust beneath the cosmic infrared background anisotropies with Wavelet Phase Harmonics

Srijita Sinha, Tuhin Ghosh, Erwan Allys et al. (+2 more)

Separating Galactic dust emission from cosmic infrared background (CIB) anisotropies is challenging because both the emission components have similar spectral properties. The primary objective of this work is to develop a component-separation algorithm to extract the Galactic dust emission from CIB anisotropies dominated sky regions using Wavelet Phase Harmonics statistics (WPH). We apply our algorithm to the Planck $353\,\mathrm{GHz}$ frequency band over three sky regions spanning a range of neutral hydrogen ($\text{HI}$) column densities at high Galactic latitudes. In all three regions, we successfully recover the dust signal without significant leakage between the dust and CIB anisotropy components. We use the low signal-to-noise ($\mathrm{S/N}$) region to validate the component-separation algorithm and compare its performance with the standard template-fit approach that uses the linear dust-$\text{HI}$ correlation relation. For intermediate and high $\mathrm{S/N}$ regions, we separate the dust signal map from the contamination while preserving the statistical correlation with $\text{HI}$ column density map. Dust maps are used to analyze the relationship between dust and $\text{HI}$ emissions. We characterize the spatial variations in dust emission relative to the hydrogen column density as a function of the angular scale.
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All authors Srijita Sinha, Tuhin Ghosh, Erwan Allys, François Boulanger, Jean-Marc Delouis

Superconductivity

Nearly Isotropic Quantum-Critical Transport in Single-Crystal CeNiC2

Hanming Ma, Jun Gouchi, Dilip Bhoi et al. (+4 more)

Pressure-induced superconductivity and $T$-linear resistivity have been reported in polycrystalline CeNiC$_2$, but orientational averaging has left the directional character of the critical scattering unresolved. We report pressure-dependent resistivity of high-quality single crystals for current along each crystallographic axis. These crystals have substantially lower residual resistivity and a slightly higher maximum onset $T_c$ than the polycrystalline sample, placing superconductivity in a cleaner transport regime. Near $P_c \approx 9.5-10$ GPa, the normal-state resistivity becomes nearly $T$-linear along every axis, the fitted residual resistivity is strongly enhanced, and superconductivity forms a narrow dome. For $I \parallel b$, the $T$-linear normal state remains nearly unchanged in magnetic fields up to 9 T applied along $a$ and $c$; the upper critical field is large and only moderately anisotropic. The common evolution along all three axes establishes a nearly isotropic quantum-critical transport regime, inconsistent with a simple low-dimensional spin-fluctuation picture and implicates valence fluctuations as the leading source of critical scattering associated with the superconducting dome.
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All authors Hanming Ma, Jun Gouchi, Dilip Bhoi, Toru Shigeoka, Bosen Wang, J.-G. Cheng, Yoshiya Uwatoko

Materials Science

Substitution effects in RuO$_2$ single crystals

Shubhankar Paul, Kunihiko Yamauchi, Shogo Yamashita et al. (+7 more)

RuO$_2$ has emerged as one of the leading candidates for investigating altermagnetism. Recent quantum oscillation and angle-resolved photoemission spectroscopy measurements found the absence of altermagnetism or antiferromagnetism in pure RuO$_2$ crystals. The continuing debate over intrinsic magnetic order in RuO$_2$ may reflect its proximity to an altermagnetic instability. In this work, we grow single crystals of Ru$_{0.9}$V$_{0.1}$O$_2$ and investigate their structural, transport, and magnetic properties. X-ray photoelectron spectroscopy reveals an average V oxidation state near $+4$. The paramagnetic susceptibility remains nearly unchanged up to room temperature, with no evidence of magnetic ordering. Thus, the 10% V-substitution in RuO$_2$ does not induce altermagnetism. Electronic structure calculations for the V-substituted systems using two methods suggest that a higher level of V-substitution leads to a significant change in the density of states. These findings underscore the potential of nonmagnetic substitution in RuO$_2$ as an attractive candidate for probing altermagnetic transitions and their experimental signatures.
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All authors Shubhankar Paul, Kunihiko Yamauchi, Shogo Yamashita, Hisakazu Matsuki, Shuhei Iwashita, Mitsuhiko Maesato, Hiroshi Kitagawa, Chanchal Sow, Shingo Yonezawa, Yoshiteru Maeno

Astrophysics of Galaxies

The Nobeyama 45 m Survey of Shocked Molecular Gas in the Central Molecular Zone. I. Survey Data, Cloud Catalog, and SiO Line-Ratio Trends

Shunya Takekawa, Shiho Tsujimoto, Tomoharu Oka et al. (+1 more)

We present large-scale molecular line maps of the Central Molecular Zone (CMZ) in our Galaxy obtained with the Nobeyama Radio Observatory 45 m telescope. The observations cover a 3.5 deg x 0.5 deg region with 20 arcsec resolution in eight molecular lines including SiO J=2-1, CS J=2-1, H13CN J=1-0, and HCN J=1-0. We release the calibrated data cubes and a catalog of SiO-emitting clouds identified by the SCIMES algorithm. For each cloud, we provide cloud-integrated intensities of the observed lines and derive an H13CN-based molecular gas mass and a cloud-averaged H2 number density. We compare SiO intensity ratios with the density, dynamical time, and their product n_H2 t_dyn. We find that SiO intensity ratios relative to six other molecular lines all decrease systematically with increasing n_H2 t_dyn. The tightest correlations are found for SiO/H13CN (r_s = -0.82) and SiO/CS (r_s = -0.70). The released data cubes and cloud catalog enable systematic studies of SiO enhancement, shock chemistry, and gas dynamical evolution across the CMZ.
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All authors Shunya Takekawa, Shiho Tsujimoto, Tomoharu Oka, Rei Enokiya

Statistical Mechanics

Nonequilibrium Dynamics of Simple Exclusion Processes Across Dimensions

Zhimao Liu, Jing Liu, Pan Zhang et al. (+1 more)

The simple exclusion process (SEP) is a paradigmatic model for nonequilibrium transport, yet its rich dynamics over an exponentially large configuration space remain notoriously intractable. Here, we leverage variational autoregressive networks to characterize the nonequilibrium dynamics of the symmetric (SSEP), asymmetric (ASEP), and totally asymmetric (TASEP) cases in one to three dimensions at any time. We validate the approach against established finite-time 1D and long-time 2D results for the SSEP, and further provide new results on dynamical activity, density fields and nonequilibrium phase transitions for 2D and 3D cases. In 2D, we give a directional-density criterion connecting the bulk-density organization to the 1D TASEP phase diagram, and reveal how boundary and bulk rates separately control the activity and susceptibility. In 3D, we provide the first finite-time characterization of the SSEP active-inactive phase transition, and uncover scaling relations over time. Across dimensions, the critical field follows a trend $s_c\sim L^{-2}$, suggesting tuning strategies by the characteristic diffusive length scale. Overall, this work establishes a unified neural-network framework for characterizing nonequilibrium dynamics of representative transport systems.
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All authors Zhimao Liu, Jing Liu, Pan Zhang, Ying Tang

Materials Science

Optical and magneto-optical interactions in Co-doped CeO$_2$ thin films prepared by pulsed laser deposition

Martin Zahradník, Miroslav Kučera, Roman Antoš et al. (+5 more)

Magnetically doped CeO$_2$ is a dilute magnetic semiconductor, promising for various applications in photonics, but the origin of its ferromagnetic properties is not fully understood. Here, thin films of Ce$_{1-x}$Co$_x$O$_{2-\delta}$ prepared by pulsed laser deposition on MgO ($x=0.05$ and $0.10$) and oxidized Si ($x=0.20$) substrates were systematically studied by spectroscopic ellipsometry and magneto-optical spectroscopy. Both diagonal and off-diagonal permittivity-tensor elements were obtained. Diagonal spectra revealed two optical transitions between oxygen and cerium states. Off-diagonal spectra revealed two paramagnetic transitions involving cobalt ions, from which an essential influence of cobalt doping on resulting ferromagnetic properties of CeO$_2$ was inferred. The full permittivity-tensor spectra are provided for further use in prospective modelling of magneto-optical device concepts.
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All authors Martin Zahradník, Miroslav Kučera, Roman Antoš, Martin Veis, Jan Mistrík, Lei Bi, Hyun-Suk Kim, Caroline A. Ross

Instrumentation and Detectors

Development and Commissioning of the Cryogenic Target Detectors for the Technical Run of the NUCLEUS Experiment

N. Schermer, H. Abele, G. Angloher et al. (+57 more)

The NUCLEUS experiment aims to study coherent elastic neutrino-nucleus scattering (CE$\nu$NS) of reactor electron antineutrinos at the Chooz nuclear power plant in France. In this work, the cryogenic target-detector module for the NUCLEUS Technical Run was developed and commissioned at the Technical University of Munich. The module comprises four gram-scale CaWO$_4$ detectors, each equipped with two Transition Edge Sensors (TES), providing a total target mass of 6.96 g. We present the design, integration, detector characterization, and X-ray-based energy calibration of these detectors. Across six characterized detectors, a mean baseline resolution of $\overline{\sigma}_{\mathrm{BL}} = (2.79 \pm 0.60)\,\mathrm{eV}$ was achieved. The best-performing detector reached $\sigma_{\mathrm{BL}} = (2.16 \pm 0.02_{\mathrm{stat}})\,\mathrm{eV}$, surpassing the design goal by a factor of two and representing a state-of-the-art result for a cryogenic CaWO$_4$ detector. The target detector module was successfully operated simultaneously with the surrounding Cryogenic Outer Veto, which consists of six kg-scale Ge detectors for background discrimination, showing no measurable cross-talk. These results demonstrate the readiness of the target-detector system for the NUCLEUS Technical Run at Chooz and mark a key milestone in the development of cryogenic detectors for reactor-CE$\nu$NS measurements.
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All authors N. Schermer, H. Abele, G. Angloher, B. Arnold, M. Atzori Corona, A. Bento, E. Bossio, F. Buchsteiner, J. Burkhart, F. Cappella, M. Cappelli, N. Casali, R. Cerulli, A. Cruciani, G. Del Castello, S. Dorer, A. Erhart, M. Friedl, S. Fichtinger, V.M. Ghete, M. Giammei, J. Hakenmüller, D. Hauff, M. Hock, F. Jeanneau, E. Jericha, M. Kaznacheeva, H. Kluck, A. Langenkämper, T. Lasserre, D. Lhuillier, M. Mancuso, B. Mauri, A. Mazzolari, L. McCallin, H. Neyrial, C. Nones, L. Oberauer, L. Peters, F. Petricca, W. Potzel, F. Pröbst, F. Reindl, M. Romagnoni, J. Rothe, J. Schieck, S. Schönert, C. Schwertner, L. Scola, L. Stodolsky, A. Schröder, R. Strauss, R. Thalmeier, C. Tomei, L. Valla, M. Vignati, M. Vivier, A. Wallach, P. Wasser, L. Wienke

Mathematical Physics · Cross-listed from math.AG

On monodromy of monodromy surfaces

Pieter Roffelsen and Alexander Stokes

Different instances of the Riemann-Hilbert correspondence relate initial value spaces of Painlevé equations to affine varieties known as monodromy surfaces, built from monodromy invariants for associated linear ODEs. We show that these affine varieties admit realisations as embedded affine del Pezzo surfaces, characterised by their degree and a prescribed divisor at infinity, first in this paper for cases associated with Painlevé equations $\rm{VI},\rm{IV},\rm{II},\rm{I}$. We prove that the monodromy groups of these monodromy surfaces form the finite parts of the affine Weyl symmetry groups of the corresponding Painlevé equations. We realise the monodromy group in each case: analytically as permutations of lines induced by continuation along loops in parameter space, Galois-theoretically in terms of the function field of the incidence variety of lines, and combinatorially via their intersection graph. This in particular yields an interpretation of the parameter spaces of Painlevé equations, modulo symmetries, as moduli spaces of categories of embedded affine varieties. Further, it shows that, despite the affine Weyl group symmetries becoming trivial when conjugated by the corresponding Riemann-Hilbert map, the finite Weyl group part survives as monodromy of the monodromy surface.
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Materials Science

A Hierarchical Synergistic Deep Learning Framework Integrating Composition, Structure, and Ionic Transport for Solid-State Electrolyte Discovery

Hongwei Du, Dingyang Lv, Baole Wei et al. (+5 more)

Inorganic solid-state electrolytes must combine high room-temperature ionic conductivity, a wide electrochemical window, excellent electronic insulation, and favorable mechanical compliance. Single models struggle to support reliable multi-objective screening across vast chemical spaces because of training-data distribution mismatch, cross-property dataset heterogeneity, and scarce kinetic transport data. To overcome these limitations, we develop a hierarchical synergistic deep-learning framework that sequentially coordinates efficiency, accuracy, and reliability through four complementary modules. The in-house-developed L-G-DCNN and a multi-fidelity implementation built on DenseGNN serve as compositional and structural experts for thermodynamic coarse screening and multi-property evaluation, respectively; MatterSim and system-specific DeePMD models provide transport pre-assessment and kinetic validation. Systematic benchmarks show that each module outperforms mainstream counterparts in its task, while retrospective validation establishes dual closed-loop verification of module-level accuracy and end-to-end workflow reliability. Applied to 30,364,908 Alex/ICSD-derived candidates, the framework identifies 97 high-performance candidates with room-temperature ionic conductivities of 0.109–59.0 mS/cm, including 94 halides, one borohydride, and two oxides. Consistency with independent experimental data confirms that 76 of the 94 halides fall within reported high-conductivity structural regions. Analysis reveals that Li$^{+}$ jump-network connectivity, rather than the number of geometric Li sites, is the core determinant of room-temperature ionic conductivity. Li-defect engineering effectively enhances oxide transport, whereas the inherent rigidity of the O$^{2-}$ framework suggests a potential upper limit on oxide electrolyte performance.
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All authors Hongwei Du, Dingyang Lv, Baole Wei, Yongheng Li, Feng Yu, Ziheng Lu, Siqi Shi, Hong Wang

High Energy Physics (Phenomenology)

Quantum-Kinetic Leptogenesis and Gravitational Waves from Seesaw-Assisted Domain-Wall Dynamics

Gayatri Ghosh

We investigate the connection between resonant leptogenesis and a primordial stochastic gravitational-wave background in a minimal two-right-handed-neutrino type-I seesaw with a real singlet scalar. The scalar sector admits a $\mathbb Z_2$-symmetric tree-level potential, while the tiny right-handed-neutrino coupling to the $\mathbb Z_2$-odd scalar generates a radiative vacuum-energy bias that causes the domain-wall network to annihilate. For quasi-degenerate heavy neutrinos, we describe the heavy-neutrino system with a density-matrix kinetic framework and use the ratio $r_q=\Delta M/\Gamma_{N_1}$ as an organizing variable for the separated, resonant and coherent regimes. The heavy-neutrino parameters that control the physical mass splitting also enter the radiatively generated domain-wall bias, providing a model-dependent link between the quantum-kinetic baryon asymmetry and the gravitational-wave peak frequency and amplitude. We emphasize that the gravitational- wave signal is not a direct measurement of an individual low-energy neutrino parameter; rather, it provides a model-dependent consistency relation among neutrino data, resonant leptogenesis, domain-wall annihilation and the stochastic gravitational-wave background.
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High Energy Astrophysical Phenomena

Weak gravitational lensing by a dark-matter-admixed neutron star: a self-consistent two-fluid halo and the Gauss–Bonnet deflection angle

Yashmitha Kumaran and Ilídio Lopes

We compute the weak gravitational deflection of light by a neutron star that carries a self-consistent dark-matter component, in the regime in which the dark matter forms an "extended halo" reaching beyond the baryonic surface. Two observations motivate this configuration. First, a dark-matter core confined within the baryonic radius leaves no distinctive lensing signature, since by Birkhoff's theorem the exterior is Schwarzschild with the total mass, so a ray passing outside the star feels only that mass and the compactness it implies. Second, the signature we seek resides in the complementary case, in which the ray genuinely traverses the halo, so that the surrounding density enters the optical geometry directly. We model the star by integrating the coupled two-fluid Tolman–Oppenheimer–Volkoff equations, with the baryonic and dark components interacting solely through gravity, and we obtain the deflection angle from the resulting external profile through the Gibbons–Werner construction of the Gauss–Bonnet theorem. The defining feature of the approach is that the deflection is tied to a "self-consistent" two-fluid profile rather than to a medium inserted by hand. We show that, for impact parameters smaller than the halo radius, the deflection departs measurably from the point-mass prediction, the deficit being governed by the dark-matter fraction and the halo extent, and we argue that the "shape" of this deficit furnishes a geometric, lensing-based handle on the degeneracy between dark matter and the nuclear equation of state. The framework thereby unites the structural modelling of compact stars with their gravitational-lensing phenomenology.
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Materials Science

Exchange splitting as a descriptor for giant anomalous Hall and Nernst effects in ferromagnets

Ivan Kurniawan, Guangzong Xing, Yoshio Miura et al. (+1 more)

The anomalous Hall effect (AHE) and anomalous Nernst effect (ANE), which describe transverse electrical and thermoelectric responses in magnetic materials, respectively, are promising for spintronic and energy-harvesting applications. Here, we employ high-throughput first-principles calculations to investigate 2251 chemically substituted tetragonal $L1_0$ alloys. Among ferromagnets, enhanced responses emerge preferentially in alloys derived from parent compounds with small exchange splitting: no alloy derived from FePt, the archetypal $L1_0$ ferromagnet, reaches the high-response regime, whereas NiPt- and CoIr-derived alloys occupy it in large numbers. Small exchange splitting keeps majority- and minority-spin bands near the Fermi level, giving chemical substitution more opportunity to modify near-Fermi-level band crossings and amplify the Berry curvature. We predict a giant anomalous Hall conductivity of $2809\,\mathrm{S\,cm^{-1}}$ in (Co$_{0.8}$Fe$_{0.2}$)(Ir$_{0.7}$Pt$_{0.3}$) and a giant anomalous Nernst conductivity of $7.72\,\mathrm{A\,m^{-1}\,K^{-1}}$ in (Ni$_{0.8}$Co$_{0.2}$)(Pt$_{0.7}$Ir$_{0.3}$). Our results identify the exchange splitting of the parent compound as a descriptor for chemical tunability toward giant Berry-curvature-driven transport responses.
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All authors Ivan Kurniawan, Guangzong Xing, Yoshio Miura, Keisuke Masuda