Computational Physics · Cross-listed from cs.LG
Gradient-based inverse lithography for EUV masks via the waveguide method and a physics-informed neural operator
Vasiliy A. Es'kin and Egor V. Ivanov
Gradient-based inverse lithography technology~(ILT) for extreme ultraviolet~(EUV) masks is presented. A novel framework treats the differentiable waveguide method and the recently proposed waveguide neural operator~(WGNO) as end-to-end physics engines, recovering the permittivity of the absorber of the mask through automatic differentiation of the full forward diffraction model. Numerical experiments on realistic 2D and 3D absorbers of the mask (TaBN, La, U) at $\lambda{=}11.2$~nm show that the considered ILT methods make it possible to obtain a mask structure that achieves the desired field on the wafer.
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Fluid Dynamics
Bulk-to-Wall Observability in Rarefied Hypersonic Flow: Moment Limits and Incident Half-Range Sufficiency
Elyas Lekzian and Ehsan Roohi
Wall traction in a rarefied gas is a half-range functional of molecules arriving at and leaving a surface, whereas hybrid solvers, moment methods, and learned wall models often transmit only finite full-range moments. We determine which directional information is lost and what restores the wall functional using direct simulation Monte Carlo (DSMC) of Mach-6 flow over three triangular-protrusion orientations. Output-specialized neural networks interpolate a 57-condition DSMC database. A distinct ExtraTrees regression holds learner capacity, auxiliary features, train/test split, and seeds fixed while comparing the primitive state $S_0$, the momentum-flux-augmented state $S_1$, and the heat-flux-augmented state $S_2$. Adding the momentum-flux tensor $P_{ij}$ reduces aggregate pressure error by 31% but does not make signed shear transferable. An analytic null-space construction supplies the mechanism: strictly positive distributions can share all full-range moments through degree three while producing different pressure and opposite signed shear because the wall kernel selects the incident half space. A finite-distance off-wall ExtraTrees state $S_{\mathrm{off}}$ shows that partial directionality is useful but representation-dependent. Finally, a parameter-free kinetic reconstruction combines the incident half-range wall-arrival state $S_{\mathrm{HR}}$ with the prescribed diffuse kernel and agrees with both a same-window DSMC tally sharing the incident events and a separate 40,000-step DSMC wall-tally window. The resulting design principle is direct: a rarefied wall closure must preserve the incident normal–tangential correlations required by the target load rather than merely adding higher full-range moments.
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Fluid Dynamics
A Novel Methodology for Evaluating Positive Phase Blast Wave Loading Parameters Using High Speed Video
Caio Barbosa Amorim, Clare Knock, Dain George Farrimond et al. (+1 more)
Traditionally, the critical blast wave parameters used to characterize loading conditions are obtained through pressure gauge measurements. However, these instruments are costly, require careful calibration, provide discrete location measurements only, and must be deployed in hazardous environments. Recent events, such as the Beirut port explosion have demonstrated that
video recordings, which provide time of arrival (ta) versus distance data, offers valuable information for post-event blast analysis. However, methodologies capable of predicting key blast parameters, such as positive phase duration and impulse, using
video data alone remain limited. This work proposes and validates a novel methodology to predict positive phase duration and impulse for spherical, non-cased, free air bursts of ideal explosives using ta data only. The proposed methodology was evaluated using experimental
datasets from the literature for bulk and cartridge PE4, PE7, Composition B, and PETN. The positive phase duration and impulse models achieved, respectively, mean absolute percentage errors of 5.3% and 5.3%, maximum deviations of 20% and 9.4%, absolute biases of zero and 3.1%, and confidence interval coverages of 86% and 83%. The predicted results achieve remarkable comparison to all reported experimental data, verifying the ability to capture positive phase blast loading for high speed
video; a step-change in explosive characterisation through full spatial and temporal primary shock characteristics.
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All authors Caio Barbosa Amorim, Clare Knock, Dain George Farrimond, Rene Francisco Boschi Gonçalves
Fluid Dynamics
Dynamic masking for boundary-aware velocity reconstruction in volumetric particle tracking with moving solids
Jibu Tom Jose, Arieh Jacobson, Dhanush Vittal Shenoy et al. (+2 more)
Volumetric particle tracking velocimetry (PTV) produces scattered Lagrangian tracks that must be reconstructed on an Eulerian grid before velocity gradients, pressure, or hydrodynamic loads can be evaluated. This step is usually performed on a domain treated as entirely fluid. When a solid body lies within the measurement volume, its surface kinematics are not imposed and the reconstruction is weakest in the steep-gradient region next to the body. We introduce LE-DM (Lagrangian-to-Eulerian reconstruction with Dynamic Masking), a constrained reconstruction framework for moving solid boundaries. A time-dependent signed-distance function classifies grid nodes as open fluid, boundary shell, or solid interior. The particle data, incompressibility constraint, prescribed surface velocity, and regularization terms are then assembled on the masked domain within a single solve. The method requires only a signed-distance field and a surface velocity, allowing stationary walls, translating, rotating, multiple, and deforming bodies to be represented in the same formulation. LE-DM is assessed using an analytical oscillating sphere, synthetic tracks from a CFD rising-sphere simulation, and a refractive-index-matched tomographic-PTV experiment on a freely rising sphere. The surface kinematics are enforced to solver tolerance, while the bulk reconstruction remains unchanged where no body is present. In the analytical case, the first-
cell error is reduced from 14% to 3% of the body speed. In the experiment, LE-DM recovers the independently measured surface velocity, whereas an all-fluid reconstruction does not. The result is a divergence-free, boundary-consistent velocity field for pressure and force estimation.
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All authors Jibu Tom Jose, Arieh Jacobson, Dhanush Vittal Shenoy, Steven H. Frankel, Omri Ram
Astrophysics of Galaxies
Exploring the physics of ram pressure stripping with radio continuum observations in the SKA era
Alessandro Ignesti, Ian D. Roberts, Henrik W. Edler et al. (+4 more)
Satellite
galaxies in clusters are significantly more likely to be red and passive than similar mass
galaxies in the field. This fact is known as the environmental quenching of
galaxy star formation, which is believed to be driven by ram pressure stripping (RPS). The large velocity differences between the infalling
galaxies and the intracluster medium (ICM) result in a strong ram pressure on their interstellar medium (ISM), which can strip it from the
stellar disk. The stripped ISM can be studied at various wavelengths, including the
radio band, thanks to the synchrotron emission produced by the
magnetic fields and relativistic electrons embedded in them. This emission is typically steep-spectrum and thus best observed at low frequencies. Thus, continuum studies of the RPS effect are currently mostly carried out with LOFAR, limiting them to the northern hemisphere. SKA-Low will permit us to extend them to the southern sky, where they will synergize with the southern observatories and the upcoming ELT. Lastly, the sub-arcsecond resolution provided by SKA-Mid will facilitate the exploration of the polarization and filamentary structure of RPS
radio tails and allow us to detect them up to $z\simeq0.5$, advancing our understanding of the impact of RPS on satellite
galaxies in clusters and groups.
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All authors Alessandro Ignesti, Ian D. Roberts, Henrik W. Edler, Myriam Gitti, Reinout J. van Weeren, Paolo Serra, Pavel Jachym
Materials Science
Barocaloric phase transformation from data efficient fine-tuning of machine learned interatomic potentials
Ludwig Hedin and Johan Klarbring
Solid-state cooling based on the barocaloric (BC) effect has emerged as promising environmentally friendly prospective alternative to conventional vapor-compression refrigeration. The search for suitable BC materials relies on efficient atomistic simulations of their phase behavior. Machine-learned interatomic potentials (MLIPs) enable such simulations at near density functional theory (DFT) accuracy, but generating the required DFT training data remains computationally demanding, which motivates development of strategies that reduce the amount of data needed to train accurate models. In this work, we use a prototypical BC material, ammonium sulfate, as a model system and investigate how small a training set can be while still reproducing the temperature-driven structural phase transformation that underlies its BC response. We train a series of MLIPs based on the MACE architecture using three strategies: training from scratch, and naive- and multihead replay fine-tuning of the MACE-MPA-0 foundation model. These strategies are evaluated on their ability to reproduce the phase transformation of ammonium sulfate in molecular dynamics simulations across a range of training-set sizes. We find that, while the MACE-MPA-0 foundation model itself fails to reproduce the transformation, and models trained from scratch break down for small
datasets, fine-tuned models reproduce the transformation using as few as 5 to 10 60-atom DFT configurations. Both fine-tuning protocols yield similarly accurate results for ammonium sulfate, but we also find some indications that multihead replay fine-tuning is more robust on configurations outside the fine-tuning domain. Exploiting this data efficiency, we further show that models can be trained on small
datasets and the hybrid-DFT level, and that some form of inclusion of dispersion correction is necessary to describe the phase behavior correctly.
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High Energy Astrophysical Phenomena
Multi-Band Optical Variability of Blazar 1ES 2344+514 on Diverse Time-Scales
Aykut Özdönmez
This study presents the results of multi-band observations from 2022 to 2024 and Zwicky Transient Facility (ZTF) observations from 2018 to 2023, examining the flux variability of the blazar 1ES 2344+514 on diverse time-scales in the optical bands. The blazar has mild short-term variability (STV) and long-term variability (LTV), with small amplitudes of $\sim0.7$ mag and 0.4 mag for the host subtracted- and included-light curves, respectively. The power-enhanced F-test and the nested Analysis of Variance (ANOVA) statistical tests of the six intra-day light curves show that the blazar has no minute-scale variability. The multiband color behavior analysis revealed a moderate redder-when-brighter (RWB) trend on intra-day time scales, while the LTV shows no detectable color behavior. We found a strong correlation between the ZTF optical light curves without any time lag, but no detectable correlations for the optical band emissions. From our periodicity searches using WWZ and LS methods, three significant quasi-periodic oscillation (QPO) signals in the ZTF light curves are found at about 1.02, 1.3, and 2.85 years. The observational results indicate that the blazar 1ES 2344+514 has a complex variability while emphasizing the need for future observations to unravel its underlying mechanisms.
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Exactly Solvable and Integrable Systems · Cross-listed from math.CA
A 2+1-dimensional extended Dym equation: moving boundary problems solvable via Painlevé II symmetry reduction
Colin Rogers and Pablo Amster
A 2+1-dimensional extension of the solitonic Dym equation is shown to admit a Painlevé II
symmetry reduction which permits the exact solution of a class of Stefan-type moving boundary problems.
Quantum Physics
Radial Schmidt mode detector of entangled photons
Radhika Prasad, Nilakshi Senapati, Abhinandan Bhattacharjee et al. (+1 more)
High-dimensional spatially entangled two-
photon state generated by spontaneous parametric down-conversion process (SPDC) has become a promising resource for several
quantum information science applications. For harnessing high-dimensional
entanglement advantages, detection capability in the Schmidt basis is a necessity. Spatial
entanglement has been explored in several modal bases, such as pixel, azimuthal, and radial modes. Among them, pixel and azimuthal
entanglement have been widely utilized due to efficient access to their Schmidt modes, while radial-mode
entanglement remains underexploited. This is because for radial coordinates, there is neither a Schmidt-decomposed form for the SPDC
photons nor is there a technique for measuring high-dimensional radial Schmidt modes, which is a major roadblock in harnessing radial mode advantages. In this work, we first theoretically show that the azimuthal averaging of SPDC two-
photon state yields a radial Schmidt-decomposed form under typical experimental situations. We then demonstrate an innovative approach for extracting the radial Schmidt modes and their spectrum by characterizing the density
matrix in the radial basis of one of the SPDC
photons. Finally, we report the first-ever measurement of radial Schmidt spectrum of upto 50 radial Schmidt modes with about 98% fidelity.
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All authors Radhika Prasad, Nilakshi Senapati, Abhinandan Bhattacharjee, Anand K Jha
High Energy Physics (Phenomenology)
Decay constants of the $B_c$ mesons with vector and tensor currents
Eduard Costa i Reina, Nico Gubernari and Zachary Wüthrich
We calculate the decay constants of the lowest-lying $B_c$
mesons in the
spin-parity channels $J^P = 0^-,\,0^+,\,1^-,\,1^+$, commonly referred to as the $B_c,\, B_{c0}^*,\, B_c^*,\, B_{c1}$
mesons, respectively. Within the framework of QCD sum rules, we consider the decay constants associated with both the (axial-)vector and (axial-)tensor interpolating currents. The decay constants with (axial-)vector currents have already been studied in the literature. We refine previous QCD sum rule results by including higher-order power corrections and performing a comprehensive uncertainty analysis. Furthermore, we provide the first determination of the (axial-)tensor decay constants of the $B_c^*$ and $B_{c1}$
mesons. These new results will not only improve theoretical predictions for purely leptonic $B_c$ decays, but also strengthen unitarity constraints on $b \to c$ form factors, thereby improving the precision of predictions for $\bar{B} \to D^{(*)} \ell \bar\nu$ decays and the determination of $|V_{cb}|$.
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Cosmology and Nongalactic Astrophysics
The SKA View of Cool-core Clusters: Evolution of Radio Mini-halos and AGN Feedback
Myriam Gitti, Paolo Tozzi, Francesco Ubertosi et al. (+12 more)
In about 70 per cent of relaxed, cool-core
galaxy clusters, the brightest cluster
galaxy (BCG) is
radio loud, showing non-thermal
radio jets and lobes ejected by the central active
galactic nucleus (AGN). In recent years such relativistic
plasma has been shown to interact with the surrounding thermal intra-cluster medium (ICM) as revealed by striking images where
radio lobe fill the cavities in the X-ray-emitting gas. This "
radio-mode feedback" phenomenon is widespread and crucial for understanding the physics of cluster cores and the properties of the central BCG. Mechanically-powerful AGN are expected to drive
turbulence in the central ICM which may also contribute to the origin of non-thermal emission on cluster-scales. Diffuse non-thermal emission has been observed in many cool-core clusters in the form of a
radio mini-
halo surrounding the
radio-loud BCG on scales comparable to the cooling radius. Large samples of mini-
halos are essential to clarify their origin and their link with the thermal and dynamical properties of clusters, especially in view of future high-resolution X-ray studies with NewAthena X-IFU. All-sky surveys with the SKA-Mid
telescope at arcsecond resolution would have the potential to detect up to about 3500 mini-
halos at
redshift z<1 (compared to the few tens currently known). Deep Tier surveys with the SKA-Mid at sub-arcsecond resolution would further enable a complete census of
radio-loud BCGs down to 1.4 GHz powers of 10^23 W/Hz up to z~2. This will provide a comprehensive view of AGN feedback and its role in shaping large scale structures.
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All authors Myriam Gitti, Paolo Tozzi, Francesco Ubertosi, Annalisa Bonafede, Gianfranco Brunetti, Rossella Cassano, Stefano Ettori, Luigina Feretti, Marie-Lou Gendron-Marsolais, Simona Giacintucci, Julie Hlavacek-Larrondo, Alessandro Ignesti, Giulia Macario, Mamta Pandey-Pommier, Tiziana Venturi
Cosmology and Nongalactic Astrophysics
Probing High-redshift Intracluster Medium Using SKA
Ramananda Santra and Ruta Kale
Galaxy clusters host vast reservoirs of magnetised
plasma in their intracluster medium (ICM), where
turbulence and shocks generated during structure formation sometimes give rise to diffuse synchrotron emission in the form of
radio halos and relics. However, the origin and amplification of the
magnetic field in the ICM remains among the least understood problems, particularly at high
redshift, where direct detections are scarce. Recent observations of clusters at z $\gtrsim 0.6$ have revealed
radio powers of the diffuse sources comparable to those of nearby systems, implying that efficient
magnetic amplification suppressed inverse Compton losses. Such rapid growth of the
magnetic fields after a few Gyrs of the Big Bang challenges standard dynamo timescales, and it raises fundamental questions about the mechanisms that strengthened cluster
magnetic fields. In this chapter, we highlight the massive merging system El Gordo (ACT-CL J0102$-$4915, z$\sim$0.87) as a unique testbed for investigating theoretical models under extreme conditions. Proposing as a SKA science verification target, El Gordo will allow detailed studies of the ICM
magnetic field structure, strength through broadband continuum and polarisation measurements with SKA-Low and SKA-Mid, across staged deployments starting from AA0.5 to AA4, reaching a physical resolution of $\sim$ 20-30 kpc at our
redshift of interest. We further outline how upcoming SKA surveys will build statistical samples of high-
redshift clusters, enabling tests of different models of
magnetic fields and
cosmic rays in the formation of large-scale structure.
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Astrophysics of Galaxies
Ly$\rm \alpha$ halos and UV continuum morphologies of Tadpole Galaxies at $z> 3$
Manish Kataria and Kanak Saha
Tadpole and clump-chain
galaxies are a morphologically distinct population among high-
redshift star-forming
galaxies whose disturbed structures may influence the escape and propagation of Ly$\alpha$
photons. We investigate the Ly$\alpha$ and UV continuum properties of 12 tadpole
galaxies in the
redshift range of z $\sim$ 3 – 5.5 identified in the Hubble Ultra Deep Field (HUDF) using deep MUSE observations. Accounting for their elongated morphologies, we construct surface brightness profiles and characterize the spatial extent of their Ly$\alpha$ emission. Extended Ly$\alpha$
halos are detected in 10 of the 12
galaxies, demonstrating that diffuse Ly$\alpha$ emission is common among tadpole systems. Approximately 40% of the sample exhibits double-peaked Ly$\alpha$ profiles. While the effective radii ($\rm R_{e}$) of the Ly$\rm \alpha$ emission generally follow the spatial extent of the UV continuum, the Ly$ \rm \alpha$
halos are typically more symmetric and often exhibit spatial offsets from the
stellar component. Some
galaxies also display asymmetric and
outflow-like Ly$\rm \alpha$ structures suggestive of anisotropic escape and complex radiative transfer effects. Together, these results suggest that the disturbed morphologies of tadpole
galaxies may influence the transport of Ly$\rm \alpha$
photons and contribute to the formation of extended Ly$\rm \alpha$
halos in the circumgalactic medium.
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High Energy Physics (Phenomenology)
Spin-dependent neutrino oscillations in torsion backgrounds: A quantum-field-theoretic analysis
Raoul Serao, Giuseppe De Maria, Simone Monda et al. (+2 more)
We study
neutrino mixing in a background with spacetime torsion within the
quantum-field-theoretic formulation of
flavor oscillations. Working in the Einstein–Cartan framework and neglecting
curvature, we quantize Dirac fields in constant and linearly time-dependent axial-torsion backgrounds. A constant spatial torsion component lifts the degeneracy between the two
spin orientations through
spin-dependent effective masses and energies. In
quantum field theory this splitting modifies not only the oscillation frequencies but also the amplitudes, because the Bogoliubov coefficients entering the
flavor operators depend on
spin. The effect is largest at low momentum when the torsion scale is comparable to the
neutrino masses, while a dominant torsion term suppresses the relative mass splittings and can inhibit
flavor conversion. We also discuss the induced
spin dependence of the Dirac $CP$ asymmetry and of the condensate densities in the
flavor vacuum. The results identify nonrelativistic
neutrinos as the natural regime in which the difference between the field-theoretic and
quantum-mechanical descriptions is most pronounced.
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All authors Raoul Serao, Giuseppe De Maria, Simone Monda, Aniello Quaranta, Antonio Capolupo
Quantum Gases
Effect of Two-Body Interactions on Floquet topological phases
Arijit Dutta, Souradeep Roy Choudhury, Tao Qin et al. (+1 more)
We study the circularly driven Falicov-Kimball model on a honeycomb
lattice within real space Floquet dynamical mean field theory (DMFT). The noninteracting version of this model has been realized experimentally. The noninteracting system hosts an effective Haldane phase at large driving frequencies, while at intermediate frequencies it hosts an anomalous topological phase. We study the effect of two-body interactions $U$ on the stability of these phases. We find that charge pumping does not remain quantized upon increasing $U$, despite the presence of edge modes in the spectrum. This can be attributed to the broadening of the edge modes due to interaction. We also calculate the rate of energy dissipation into the bath and find remarkably different behaviour in the two regimes.
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All authors Arijit Dutta, Souradeep Roy Choudhury, Tao Qin, Walter Hofstetter
Biological Physics
Mechanical control of the height distribution of adsorbed viral capsids
Yeraldinne Carrasco Salas, Kassandra Gérard, Lauriane Lecoq et al. (+4 more)
The height of viral particles adsorbed on solid substrates is governed by the
equilibrium between adhesion energy and capsid elasticity. While the resulting height distribution has been proposed as a non-invasive proxy for viral sti$\hookleftarrow$ness, the physical origin of its broadening is unknown. In this work, we combine Atomic Force Microscopy (AFM) topography measurements of Adeno-Associated Virus (AAV8) and Hepatitis B Virus (HBV) with a theoretical shell-deformation model to identify the determinants of height dispersion. By modeling the viral shell as an elastic body under adhesive load, we evaluate the relative contributions of thermal fluctuations and mechanical heterogeneity to the observed height dispersion. We demonstrate that thermal noise is insu cient to explain the width of the distribution. Instead, the data support a model where the dispersion in height arises from the intrinsic variability of capsid sti$\hookleftarrow$ness. This variability is associated to the surface inhomogeneity of identical capsids. Our results validate that, when this inhomogeneity is accounted for, the height distribution of adsorbed particles provides a quantitative measure of viral mechanics without the need for individual nanoindentation.
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All authors Yeraldinne Carrasco Salas, Kassandra Gérard, Lauriane Lecoq, Anna Salvetti, Fabien Montel, Cendrine Faivre-Moskalenko, Martin Castelnovo
Soft Condensed Matter
Asymmetry-Induced Chiral Dynamics in Coupled Self-Propelled Robots: Spinning and Circular Motion
Priyanka, Nitin Kumar and Harsh Soni
Motivated by the
chiral motility of microswimmers, we investigate how
geometric asymmetry in a system of two self-propelled active Brownian
robots coupled by a spring gives rise to rich collective dynamics. We demonstrate that asymmetry in the propulsion directions of the
robots generates net torques that induce persistent rotational motion. Depending on the choice of propulsion angles $\alpha_1$ and $\alpha_2$, the system exhibits three distinct dynamical regimes – run-and-tumble motion, circular trajectories, and spinning – with the
geometric configuration primarily determining the realized regime. We further show that spring stiffness and rotational noise act as additional tuning parameters governing the stability of these regimes. These results demonstrate how the interplay of mechanical coupling and activity produces diverse self-organized dynamics in simple robotic dimers, providing a bridge between artificial active systems and biological microswimmers such as bacteria, Chlamydomonas reinhardtii, and spermatozoa.
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Nuclear Theory
$K^-$-Driven Direct Urca Cooling in Rotating Neutron Stars: A Bayesian Study
Aprajita Shrivastava, Debanjan Guha Roy and Sarmistha Banik
We investigate the onset of antikaon ($K^-$) condensation and its implications for the equation of state (EoS) and cooling of
neutron stars (NSs) within density-dependent relativistic mean-field parametrisations DD2 and MPE. Treating the antikaon - nucleon optical potential ($U_K$) as a free parameter in the range $[-180,-60]$ MeV, we constrain it using
Bayesian inference with NICER mass-radius observations of PSR J0030+0451 and PSR J0740+6620. The inferred posterior distributions favour strongly attractive in-medium $K^-$ interactions, while their broad widths indicate only weak constraints on $U_K$ by astrophysical observations. More attractive values of $U_K$ lead to an earlier onset of $K^-$ condensation, enhanced softening of the EoS, and lower Direct Urca (DU) threshold densities. The condensation threshold is systematically lower in DD2 than in MPE, while finite
entropy further promotes the onset of rapid cooling. The $K^-$-induced enhancement of the
proton fraction ($y_p$) substantially affects a larger volume of the
stellar core, i.e. capable of sustaining rapid DU cooling. We further show that rapid rotation suppresses DU cooling by reducing the central density and $y_p$, thereby shrinking the DU-active core. This suppression is more pronounced for MPE than for DD2. Our results demonstrate that $K^-$ condensation, finite
entropy, and rotation jointly exert a strong influence on the conditions for rapid
neutrino cooling in NSs.
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Instrumentation and Methods for Astrophysics
DANTE: A Reference-Guided Unsupervised Pipeline for Extended-Transient Anomaly Characterization in LIGO O4a
Luca Cirfeta
The analysis of gravitational-wave detector data during the fourth observing run (O4) requires robust methods to distinguish stationary instrumental noise from non-stationary transients (glitches). In this work, we present DANTE (Domain-Adaptive Network for Transient Evaluation), a pipeline designed to discover and triage novel non-stationary artifacts entirely without labels. We demonstrate that adapting a pre-trained
Vision Transformer (DINOv2) to extract local patch
embeddings from time-frequency spectrograms allows for high-resolution mapping of transient anomalies. We formalize the Signal Dilution Barrier via controlled injection tests, showing that while Multiple Instance Learning (MIL) Top-k pooling recovers extended
topologies, it is blind to sub-second morphologies. To address small-sample taxonomy instability, we introduce an adaptive Dirichlet Process Mixture Model (DPMM) that dynamically selects covariance structures. Finally, by implementing a native O4a background recalibration, we resolve the domain-shift problem, demonstrating consistency with the hypothesis that pervasive O4a morphologies (initially flagged as novel by historical references) are stationary artifacts. We conclude that unsupervised anomaly detection strictly requires native recalibration to filter domain-shift artifacts, while definitive classification of remaining unmodeled singletons requires multi-channel validation.
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Quantum Physics
Quantum steering in networks: Measurement-device-independent detection, continuous variables, and practical Gaussian schemes
Shao-Hua Hu, Chung-Yun Hsieh, Huan-Yu Ku et al. (+2 more)
We consider
quantum steering certification in multipartite networks, with a focus on minimal trust scenarios: all-except-one parties are untrusted and treated device-independently. We show that it is always possible to lift steering certification to the measurement-device-independent regime, in which even the (last) trusted party can treat their local hardware as a black-box, except for a set of fiduciary
quantum states used as the inputs to the experiment. This holds both for finite-dimensional systems as well as for bosonic continuous-variable systems, which we characterize in terms of semi-
quantum games in the bipartite case. Additionally, we introduce measurement-device-independent network steering protocols based entirely on Gaussian operations – which cannot be used for fully device-independent protocols, and thus become instead a viable option for minimal trust certification as soon as a single trusted input is inserted in the network. Our results present a basis for steering-based applications (such as randomness generation) with minimal trust beyond full nonlocality and with feasible experimental requirements.
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All authors Shao-Hua Hu, Chung-Yun Hsieh, Huan-Yu Ku, Ray-Kuang Lee, Paolo Abiuso
Astrophysics of Galaxies
Tracing the Star Formation History of the Universe through Thermal Free-Free Emission with the SKA
Hiddo S. B. Algera, Mark Sargent, Eric J. Murphy et al. (+1 more)
One of the major scientific aims of the SKA is to trace the history of
star formation across
cosmic time. High-frequency
radio surveys are indispensable in this regard, as these are capable of probing thermal free-free emission (FFE) – the dominant component of the
radio continuum of
star-forming
galaxies above rest-frame frequencies of $\gtrsim25\,$GHz. FFE is a powerful, direct
star-formation rate (SFR) indicator, which robustly traces the number of ionizing
photons produced by recently formed massive
stars in a nearly
dust-unbiased manner. In this chapter, we forecast the ability of the SKA to detect FFE in typical
star-forming
galaxies in the early Universe. Our starting point is the state-of-the-art T-RECS simulation suite of the faint
radio sky, to which we apply an ambitious, matched-depth, multi-band AA4 SKA-Mid survey in Bands 1 through 5b, covering an area of $0.25\,\mathrm{deg}^2$ across $0.35 - 15.4\,\mathrm{GHz}$. We predict that such a survey will detect $\sim1.5\times10^4$
star-forming
galaxies in all bands out to $z\approx7$, and perform simulations using established fitting techniques to investigate the accuracy with which their thermal FFE can be recovered. We find that thermal fractions ($f_\mathrm{th}$) and synchrotron spectral indices can be constrained in an unbiased manner, and predict uncertainties on the thermal SFRs of $\lesssim 0.1\,\mathrm{dex}$ for
galaxies at the knee of the
radio luminosity function across
redshift. Convolving the distribution of $f_\mathrm{th}$ inferred from the multi-band SKA-Mid survey with wider luminosity function determinations at low
radio frequencies will yield robust constraints on the total
cosmic star formation rate density out to $z\sim7$.
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All authors Hiddo S. B. Algera, Mark Sargent, Eric J. Murphy, Fangxia An
Quantum Gases
Self-Organized Stabilization of Straight Dark Solitons in Stripe Supersolids
Koushik Mukherjee and Hiroki Saito
Straight dark
solitons in two-dimensional (2D)
quantum fluids usually decay by transverse modulational instability, with no intrinsic suppression in contact-interacting Bose–Einstein condensates (BECs). We theoretically show that anisotropic long-range interactions in a quasi-2D dipolar BEC stabilize an embedded straight
soliton, with spontaneous stripe order providing stronger pinning. The excitation spectra show that the lowest transverse solitonic branch remains gapped, while stripe-supersolid density modulation further hardens this branch and increases the
soliton bending stiffness, penalizing transverse deformation. Accessible in current $^{166}$Er and $^{164}$Dy platforms, these results establish interaction-driven protection for straight dark
solitons in structured
quantum fluids.
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Earth and Planetary Astrophysics
Unveiling the Trans-Neptunian Region with the SKA
Pablo Santos-Sanz, Yücel Kilic, Thomas G. Müller et al. (+3 more)
We explore the potential of the SKA staged delivery AA4 (SKA-AA4) to detect and characterise the thermal emission of trans-Neptunian objects (TNOs) and Centaurs at centimetre wavelengths. These distant icy bodies preserve important information on the formation and
evolution of the outer
Solar System and provide a valuable link to planetary systems observed around other
stars. The unprecedented sensitivity of SKA-AA4 will enable thermal detections of several of the brightest TNOs and Centaurs, extending radiometric studies beyond the capabilities of current
radio facilities. Combined with shorter-wavelength observations and occultation measurements, these data will provide new constraints on spectral emissivity behaviour, thermophysical properties, and subsurface structure. At its highest angular resolutions, SKA-AA4 may partially resolve the largest systems, enabling investigations of surface heterogeneity, extended structures such as rings, and the partial resolution of some wide binary systems. We also assess the feasibility of
radio occultation observations, which can provide independent constraints on object sizes, shapes, atmospheres, rings, or satellites. Together with observations from ALMA, JWST, and occultation campaigns, SKA-AA4 will establish centimetre-wavelength studies as a powerful new tool for investigating the thermal and structural properties of outer
Solar System bodies.
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All authors Pablo Santos-Sanz, Yücel Kilic, Thomas G. Müller, Emmanuel Lellouch, Javier Moldón, Jorma Harju
High Energy Physics (Phenomenology)
Quark Reggeization in QCD from the Wilson line formalism
Tolga Altinoluk, Guillaume Beuf, Jules Favrel et al. (+1 more)
We establish a Wilson-line formulation of
quark Reggeization in QCD. An interpolating operator for the Reggeized
quark is identified in terms of semi-infinite Wilson lines, and its nonlinear rapidity
evolution is derived. We provide strong evidence that this operator remains an eigenstate of the rapidity
evolution up to next-to-leading logarithmic accuracy. Within the leading logarithmic accuracy, we explicitly recover the one-loop
quark Regge trajectory. Our results provide a first-principles operator framework for
quark Reggeization and pave the way for a systematic all-order description of high-energy QCD amplitudes with $t$-channel
quark exchange in terms of Wilson lines.
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All authors Tolga Altinoluk, Guillaume Beuf, Jules Favrel, Michael Fucilla
Physics and Society
Opinion Dynamics over Migration Networks
Lőrinc Márton, Stefanie Winkelmann, Mauricio J. del Razo et al. (+1 more)
Opinions play a crucial role in shaping collective phenomena such as political polarization, cultural integration and demographic change. By continuously changing social environments in which opinions evolve, human migration serves as an important driver of collective opinion formation. While migration and opinion dynamics have both been extensively studied, the few existing models that couple the two are primarily deterministic and therefore cannot capture demographic fluctuations, finite-size effects or
stochastic transitions between emergent collective states. To address this limitation, we introduce a unifying
stochastic framework for opinion dynamics over migration networks that couples local opinion transitions, demographic processes and migration between communities. The dynamics are formulated through a spatio–temporal master equation, which provides a probabilistic description of the underlying population process. From this microscopic representation, we derive deterministic mean-field equations governing the co-
evolution of community sizes and opinion compositions, thereby linking
agent-level interactions to macroscopic population behavior. Using two representative case studies, we demonstrate how stochasticity and migration can qualitatively change the emergent dynamics and collective outcomes, including the emergence of consensus, polarization and the stabilization of oscillatory opinion dynamics. These examples highlight the rich interplay between social interactions, demographic change and migration in deterministic and
stochastic settings, and they demonstrate that migration should be viewed as an integral component of collective opinion formation rather than only an external demographic process.
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All authors Lőrinc Márton, Stefanie Winkelmann, Mauricio J. del Razo, Nataša Djurdjevac Conrad
Materials Science
Rate Programmable Ionic-Redox Switching with Tunable Volatility in CuCrP2S6
Suzanne Lancaster, Francesco Calavalle, Mayank Sharma et al. (+8 more)
Metal thiophosphates are emerging as a multifunctional material platform for neuromorphic electronics due to their accessible polar phases and ion dynamics on biologically relevant timescales. While resistive switching in these materials is frequently attributed to ferroelectric or antiferroelectric polarization, the intrinsic role of ion dynamics remains underexplored. Here, we isolate and demonstrate purely ion-driven resistive switching in paraelectric CuCrP2S6. Robust and reproducible resistive switching is observed in the absence of measurable ferroelectricity. The conductance can be tuned through both voltage amplitude and sweep rate, revealing a rate dependence characteristic of ion dynamics. The resulting resistance states exhibit controllable
volatility, where switching rate determines the decay time constant of the readout current, attributed to ionic relaxation. Using either inert or reactive electrodes, we observe electrical evidence of solid-state redox activity associated with the interfacial reduction of native Cu+ ions, enabling controlled formation of filamentary conduction pathways. Analysis of this process allows extraction of the Cu+
diffusion coefficient, providing quantitative insight into the underlying transport kinetics. The understanding of ionic-redox based resistive switching in CuCrP2S6 is crucial for unleashing its full potential as a material platform for dual- or multi-mode operation.
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All authors Suzanne Lancaster, Francesco Calavalle, Mayank Sharma, Lucia Olano-Vegas, Garen Avedissian, Tanweer Ahmed, Marco Gobbi, Beatriz Martin-Garcia, Beatrice Fraboni, Felix Casanova, Luis E. Hueso
Earth and Planetary Astrophysics
Changes in Pluto's Atmosphere Based on Stellar Occultation Data from 2017 to 2023
Amanda A. Sickafoose, Michael J. Person, Carlos A. Zuluaga et al. (+14 more)
Pluto's tenuous atmosphere has $\mu$bar-level pressure and is composed primarily of ${\text{N}}_2$, with a variable haze. Its eccentric orbit combined with high obliquity leads to significant changes in
solar insolation throughout the Plutonian year. The atmosphere is supported by vapor-pressure
equilibrium with the surface ices, thus surface changes are coupled with the atmospheric properties. Volatile-transport models have anticipated Pluto's atmospheric
evolution: predictions range from collapse over the coming decades to an atmosphere that remains. Previous work claims that Pluto's atmospheric pressure monotonically increased from 1988 through 2016, that the atmosphere began freezing out in 2018-2019, and that there was a plateau as of 2020. Here, we report results from ten
stellar occultations by Pluto between 2017 August and 2023 July. Four events were multi-chord, while six were from single sites. Our results indicate a pressure plateau between the New Horizons flyby in 2015 through roughly 2021 and suggest that the atmospheric pressure has started to drop. Between 2015-2021 and 2022, the clear-atmosphere pressure at 1275 km decreased $7\pm6\%$, and it dropped $16\pm2\%$ for pressure at 1215 km when including haze. From 2017-2023, the upper atmospheric structure is consistent, while there is a change in light-curve slope in the lower atmosphere. This change-of-slope is consistent with haze particles settling over yearly or shorter timescales. Spikes in one light curve are indicative of intermittent buoyancy waves. More data are needed to confirm a recent pressure change.
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All authors Amanda A. Sickafoose, Michael J. Person, Carlos A. Zuluaga, Amanda S. Bosh, Stephen E. Levine, Tim Brothers, Bastian Knieling, Timothy A. Lister, David J. Osip, Karsten Schindler, Joe Brimacombe, Tim Carruthers, Abigail Colclasure, Anja Genade, Petro Janse van Rensburg, Stephen B. Potter, Patricio Rojo
General Relativity and Quantum Cosmology
Exploring Gravitational Wave Science Frontiers with the SKAO
Nicola Bellomo and Philippa Cole
The Square Kilometre Array Observatory (SKAO) will be an important component of the global gravitational wave network. This article provides an overview of chapter eight of the Advancing Astrophysics with the SKA II (AASKAII) book, in which gravitational waves are a new addition, since the previous edition preceded the announcement of the first detection of gravitational waves in 2016. The chapter investigates the impact that this new observatory will have on numerous gravitational wave science cases. From testing General Relativity, to measuring the properties of the nanohertz gravitational wave background and exploiting new synergies with other upcoming experiments, the SKAO will play a key role in the next decades of gravitational wave science.
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Quantum Physics
Exact Leg-Cut Influence Functional and Emergence of Gaussian Entanglement Theory in a Statistical-Dressing Ladder Model
Babatunde Moses Ayeni
The emergence of Gaussian effective field theories in low-dimensional
quantum systems is traditionally understood through top-down frameworks such as bosonization and Luttinger-
liquid theory. However, these approaches typically focus on the long-wavelength degrees of freedom in ways that do not directly track how non-Gaussian
lattice-scale correlations are progressively discarded under coarse-graining. In this work, we present an exact
lattice formulation from which this phenomenon emerges analytically. We analyze a two-leg hard-core ladder under a leg bipartition, where non-local statistical strings cross the
entanglement cut. We construct an exact
lattice influence-functional representation showing that the reduced state factorizes strictly into a product-state amplitude and a full-counting-statistics functional. By introducing a commuting linked-cluster superoperator hierarchy that bypasses Baker-Campbell-Hausdorff ordering ambiguities, we prove that the first mixedness-generating sector is strictly density-density in character. Under a specific systematic coarse-graining procedure, we analytically derive the suppression of higher-order corrections, providing a controlled, closed-form framework showing how highly non-Gaussian
lattice states evolve toward their quadratic continuum form under coarse-graining. We corroborate these analytical predictions through finite-size exact diagonalization and
entanglement-spectrum diagnostics.
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Solar and Stellar Astrophysics
Multi-thermal dynamics and transverse oscillations of solar spicules revealed by coordinated SST, IRIS, and SDO observations
Ravi Chaurasiya, Tiago M. D. Pereira and A. Raja Bayanna
% context heading (optional) {
Solar spicules are highly dynamic chromospheric jets that play an important role in the mass and energy balance of the
solar atmosphere, though their connection to the transition region and corona remains unclear.} % aims heading (mandatory) {We investigate the dynamical and multi-thermal properties of spicules, their connection to higher atmospheric layers, and their transverse oscillations and associated energy flux.} % methods heading (mandatory) {We analyse coordinated high-resolution observations from the Swedish 1-m
Solar Telescope (SST) in H$\alpha$, the Interface Region Imaging Spectrograph (IRIS) in \ion{Si}{iv} 1400~Å, and the
Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) coronal channels. Space-time diagrams, spectral analysis, and wavelet techniques are used to study temporal
evolution, Doppler velocities, and oscillatory properties. Transverse displacements of spicules are tracked to estimate wave properties and energy flux.} % results heading {Space-time analysis reveals a clear correspondence between chromospheric spicules and coronal emission in AIA 171~Å, evolving coherently with spicule extension. Doppler velocities from H$\alpha$ and \ion{Si}{iv} show opposite signs, indicating multi-thermal
plasma flows. Wavelet analysis reveals frequently dominant $\sim$3-minute oscillations, along with high-frequency transverse oscillations (65–270~s) with velocity amplitudes of 3.3–9.9~km~s$^{-1}$ and a mean energy flux of $(2.14 \pm 0.78)\times10^{3}$~W~m$^{-2}$.} % conclusions heading (optional) {These results demonstrate that spicules are multithermal, dynamic structures connected to the transition region and corona, and that transverse waves carry substantial energy, highlighting their role in coronal heating.}
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