Astrophysics of Galaxies
CROCODILE-SIDM: Tidal Formation of Dark Matter-Deficient Galaxies as a Test Case
Kenji Kihara, Kentaro Nagamine, Lissandre Bourrat et al. (+3 more)
We introduce CROCODILE-SIDM, a framework for treating self-interacting dark matter (SIDM) with the $N$-body part of GADGET4-Osaka code, as part of CROCODILE simulation family. As a test case, we investigate the impact of SIDM on the
tidal formation of dark matter-deficient
galaxies (DMDGs) with velocity-dependent cross-section models. We demonstrate that our implementation reproduces the analytic scattering rate in isolated
halos. Including dynamical friction self-consistently, we evolve a
dwarf satellite with $M_*=2\times10^8\,\mathrm{M}_\odot$ in a $\sim10^{11}\,\mathrm{M}_\odot$
halo on a decaying orbit around a massive host, comparing CDM with four SIDM cross sections for two initial satellite density profiles: a cuspy Navarro–Frenk–White (NFW) profile and a cored Burkert profile. We find that self-interactions primarily regulate the amount of DM retained between pericentric passages, and that the sign of this effect depends on the initial profile: a larger cross section retains more DM for the Burkert initial condition but less DM for the NFW initial condition. We show that this opposing behavior reflects the direction of SIDM heat conduction, which is set by the
halo's evolutionary state at infall. Core formation in the cuspy profile assists DM stripping, whereas tidally accelerated gravothermal contraction in the cored profile suppresses
tidal mass loss. Consequently, SIDM can either assist or hinder DMDG formation, depending on the satellite's inner structure, making DMDGs a potential probe of SIDM cross section.
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All authors Kenji Kihara, Kentaro Nagamine, Lissandre Bourrat, Leonard Romano, Yuri Oku, Daisuke Toyouchi
Nuclear Experiment
Reinvestigation of the Yield of the Trinity Device
Eric B. Norman, Keenan J. Thomas and Pedro V. Guillaumon
Previous published analyses of trinitite to determine the yield of the Trinity
nuclear explosion used various estimates of the fraction of fission products that became incorporated in trinitite. Furthermore, these studies utilized
nuclear data that has subsequently been revised. Utilizing a planar germanium detector, we observed gamma rays produced by the decays of both 137Cs and 239Pu from four samples of trinitite. From the observed 137Cs/239Pu ratios of and a simple analysis method based on current
nuclear data and weapons debris studies, we find an average yield of 9.1+-4.5 kilotons from our four samples. While this result is substantially lower than the established total yield of 21 kilotons, it is in reasonable agreement that attributable to fissions in the 239Pu core alone.
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High Energy Astrophysical Phenomena
Aarmed with Data: Bumps, Outflows, and Disk-like Emission in TDE 2025aarm
Aysha Aamer, Kate D. Alexander, Charlotte R. Angus et al. (+43 more)
The origin of the optical emission in
tidal disruption events (TDEs) remains one of the major outstanding questions in the field, in part due to the limited number of nearby events with high-cadence monitoring to track their evolving photometric and spectroscopic properties. We present multi-wavelength observations of the nearby ($z=0.01368$) TDE\,2025aarm, including near-daily spectroscopic coverage prior to the optical peak. Its proximity makes it one of the brightest TDEs discovered, reaching a peak magnitude of $m_r\sim15.5$ ($M_r\sim-18$). The light curve deviates from a smooth
evolution, exhibiting multiple rebrightening episodes visible in both the individual filter light curves and the bolometric luminosity. Blackbody modelling reveals that these rebrightenings are associated with an increase in temperature of $> 5,000-10,000$\,K, while the inferred photospheric radius remains approximately constant. Simultaneously, the H$\alpha$ line not only increases in blueshift but also broadens, suggesting a link between the continuum rebrightenings to changes in the kinematics of the line-forming gas. We identify a persistent absorption component at $\sim-3900$\,km\,s$^{-1}$ in multiple Balmer lines, providing further evidence for outflowing material. The H$\alpha$ profile also exhibits excess flux compared to a Gaussian on both sides of the line, inconsistent with simple scattering-dominated
outflow models. Disk-profile modelling provides evidence for the emergence of a disk-like component least $\sim20$ days after peak, with substantial changes in the disk properties between $\sim50$ and 60 days. These observations highlight the complexity of TDE emission processes and demonstrate how dense multi-wavelength monitoring can disentangle the roles of
accretion, reprocessing, and
outflows in shaping TDE emission.
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All authors Aysha Aamer, Kate D. Alexander, Charlotte R. Angus, Panos Charalampopoulos, Megan Newsome, Iair Arcavi, Giorgos Leloudas, Matt Nicholl, Jennifer Andrews, Katie Auchettl, Thomas de Boer, K. Azalee Bostroem, Y.-Z. Cai, Kenneth C. Chambers, Collin T. Christy, Sara Faris, Noah Franz, Sebastian Gomez, Maider González-Bañuelos, Mariusz Gromadzki, Paul J. Groot, Claudia Gutiérrez, Brian Hsu, Mark Huber, Thomas L. Killestein, Chien-Cheng Lin, Thomas B. Lowe, Peter Lundqvist, Dylan Magill, Seppo Mattila, Francesca Onori, Gregory S. H. Paek, Jeniveve Pearson, Miika Pursiainen, Niko Pyykkinen, Conor Ransome, Sara Romagnoli, Jennifer Shi, Manisha Shrestha, Nathan Smith, Maximilian Stritzinger, Bhagya Subrayan, Richard Wainscoat, Ziyang Y. Wang, Simon de Wet, Hannah Wichern
Mesoscale and Nanoscale Physics
A discrete Stiefel-Whitney invariant with twofold rotation symmetry
Ken Shiozaki
We review Stiefel–Whitney invariants and give a discrete formulation of an additional $\mathbb{Z}_2$ invariant for two-dimensional spinful
insulators with twofold rotation and time-reversal
symmetries (layer group $p1121'$). A singular gauge transformation specifies a real bundle over the quotient of the Brillouin
torus, whose second Stiefel–Whitney number defines the invariant. We derive its dependence on the choice of auxiliary gauge function and prove invariance under changes of Bloch frame and additivity under direct sums. The discrete formula uses overlaps of independently chosen Bloch frames and
symmetry-compatible $\mathrm{Pin}_+$ lifts on the boundary of a half Brillouin zone. Atomic and topological-
insulator models illustrate the formula and distinguish the additional invariant from the Kane–Mele index. Together with three quantized $\mathbb{Z}_2$ partial polarizations and the filling number, it labels the known stable classification $\mathbb{Z}\oplus\mathbb{Z}_2^{\oplus 4}$.
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Solar and Stellar Astrophysics
The FU Ori outburst of PR Ori B
Carlos Contreras Pena, Zsofia Nagy, Gregory Herczeg et al. (+42 more)
We report the discovery of a nearby FU Ori-type outburst (FUor), PR Ori B, in the L1641 cluster of the Orion
star-forming region. The high-amplitude variability was first identified in the NEOWISE (3-5 $\mu$m) photometry of the unresolved PR Ori binary system. Long-term, resolved optical photometric monitoring demonstrates that PR Ori B is the driver of a $\Delta G=5~$mag outburst, while PR Ori A has remained constant over the last 20 years. The near-IR spectrum of PR Ori B changes from a late K-type spectral type during quiescence to a viscously heated disk during outburst, including deep absorption in $^{12}$CO and H$_2$O bands. The optical spectrum also exhibits features that are commonly associated with FUors, including P Cygni profiles in Na I D lines and absorption in the Ca II infrared triplet. The luminosity of the outburst (L$_{acc}\sim$30–40 L$_\odot$) is similar to that commonly observed in FUors. The comparison of Spitzer/IRS and VLT/VISIR spectroscopy shows some evidence of silicate crystallisation during the outburst. PR Ori B is one of the closest and brightest FUors discovered over the last few years, only one magnitude fainter than the archetype of the class FU Ori. The proximity and brightness will allow for future high angular resolution observations to probe the physics of the inner disk and to evaluate changes in the disk due to the increased luminosity.
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All authors Carlos Contreras Pena, Zsofia Nagy, Gregory Herczeg, Jeong-Eun Lee, Agnes Kospal, Peter Abraham, Doug Johnstone, Bo Reipurth, Chul-Hwan Kim, Hyun-Il Sung, Yihan Li, Jiaze Wang, Rui Wu, Foteini Lykou, Mizna Ashraf, John Bally, Fernando Cruz-Saenz de Miera, Min Fang, Eleonora Fiorellino, Christoffer Fremling, Teresa Giannini, Jessy Jose, Mansi Kasliwal, Maria Kun, Ho-Gyu Lee, Michal Siwak, Mate Szilagyi, Sung-Yong Yoon, Zsofia Bora, Borbala Cseh, Agoston Horti-David, Zsoka Horvath, Andras Peter Joo, Csilla Kalup, Klara Lelkes, Andras Pal, Zsolt Regaly, Krisztian Sarneczky, Balint Seli, Adam Sodor, Norton O. Szabo, Zsofia Szabo, Robert Szakats, Nora Takacs, Miguel Vioque
Materials Science
First-principles investigation of structural, mechanical, vibrational, thermal, electronic and optical properties of Na3Bi: a topological Dirac semimetal
Maisha Fahmida, Syed Shovon Mahbub Mahin, Suptajoy Barua et al. (+1 more)
Exploring the properties of topological materials has remained an active area of research in condensed matter physics for the past few decades. Here, we present a first-principles investigation of the structural, elasto-mechanical, thermal, electronic, and optical properties of Na3Bi, one of the earliest discovered topological Dirac semimetals, using density functional theory. The hexagonal phase of Na3Bi is found to be both mechanically and dynamically stable, exhibiting moderate elastic anisotropy with a universal anisotropy index of 0.832. The compound displays a moderate machinability index of 2.386 alongside a low hardness value of 2.005, consistent with its predominantly brittle, covalently bonded character accompanied by a slight metallic contribution. Its comparatively low Debye temperature of 181.39K points to a mechanically soft
lattice with loosely bound atoms. Electronic structure calculations confirm semimetallic behavior, with well-defined Dirac points pinned at the
Fermi level and a
Fermi surface composed of point-like pockets. Optical analysis across a wide spectral range reveals non-selective, moderate reflectivity of 40 to 45% and, in the visible region, an unusually high refractive index reaching between 2 and 4.5. Na3Bi is additionally found to be an efficient absorber of ultraviolet radiation. Together, these findings establish a comprehensive baseline for the mechanical, thermal, and optical behavior of hexagonal Na3Bi and point to its potential relevance for acoustic damping, UV-sensing, and optoelectronic applications
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All authors Maisha Fahmida, Syed Shovon Mahbub Mahin, Suptajoy Barua, Ishtiaque M. Syed
Quantum Physics
Enhancing Pauli Correlation Encoding for quantum optimization via systematic expressivity analysis
Riku Usuki, Don Arai, Ken N. Okada et al. (+1 more)
Quantum approaches for combinatorial optimization problems have attracted considerable
attention in recent years. Among these approaches, Pauli Correlation Encoding (PCE) has emerged as a promising framework for
quantum devices with limited
qubit resources because it embeds optimization variables in expectation values of Pauli strings. However, the mechanisms underlying its performance and the reasons for its saturation remain unclear. In this work, we investigate these questions through a systematic analysis of expressivity and trainability. First, we compare PCE with classical surrogate models based on tensor networks whose structures progressively approach the
topology of the PCE
circuit. The results show that PCE attains comparable solution quality with substantially fewer trainable parameters, indicating strong parameter efficiency. Second, to determine whether the performance saturation of conventional PCE is caused by insufficient expressivity or by optimization difficulty, we perform a diagnostic expressivity test in which the
circuit is trained toward reference configurations for Max-Cut. The results show that even shallow PCE
circuits can represent strong solutions, indicating that the main bottleneck is not the representational power of the ansatz, but the trainability under the relaxed objective function. Motivated by this finding, we propose a multistage continuation framework that gradually transforms a smooth relaxed objective into a sharper objective that more closely approximates the target discrete problem. Numerical experiments on G-set instances with 800 vertices show that the proposed method consistently outperforms conventional PCE and is competitive with representative graph neural network (GNN) methods. These results clarify the main factors behind PCE performance and provide a practical strategy for improving PCE on
quantum devices with limited
qubit resources.
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All authors Riku Usuki, Don Arai, Ken N. Okada, Keisuke Fujii
High Energy Physics (Experiment)
Extended High-Mass Axion Search with an Auxetically Tuned Higher-Order-Mode Cavity
Jinsu Kim, Sungjae Bae, Junu Jeong et al. (+9 more)
Conventional high-mass
axion haloscopes based on the TM$_{010}$ mode lose detection volume as the resonant frequency increases. We report an extended
axion search using a dielectric-restored TM$_{020}$ cavity haloscope with
symmetry-preserving auxetic tuning based on a single-degree-of-freedom mechanical architecture. Using a near-
quantum-limited microwave receiver, we searched a frequency range of 4.98-5.07 GHz and exclude
axion-
photon couplings with sensitivity approaching the KSVZ
benchmark. Together with two earlier searches, the present scans extend a multi-scan program based on this architecture, yielding nearly 300 MHz of contiguous high-mass
axion coverage over 4.98-5.27 GHz, the first broad search reported with a single higher-order-mode haloscope. This work establishes higher-order-mode cavities as a practical, scalable route beyond the TM$_{010}$ volume penalty.
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All authors Jinsu Kim, Sungjae Bae, Junu Jeong, Younggeun Kim, Jihn E. Kim, Arjan F. van Loo, Yasunobu Nakamura, Seonjeong Oh, Taehyeon Seong, Yannis K. Semertzidis, Sergey Uchaikin, SungWoo Youn
High Energy Astrophysical Phenomena
The Evolution of Thermal and Non-thermal Emission Components in GRB 250920C
Jia-Ming Chen, Ke-Rui Zhu, Shan Chang et al. (+5 more)
We present a temporal and time-resolved spectral analysis of GRB 250920C using
Fermi/GBM and Swift/BAT data. The
prompt emission consists of two distinct episodes, EI and EII, separated by a significant quiescent interval. We perform
Bayesian spectral fitting with empirical, thermal, composite, and physical synchrotron models. In EI, the spectra show clear evidence for an additional thermal component. The BB+PL model is preferred in most bright time bins, and joint
Fermi/GBM+Swift/BAT fits further support the presence of this component. The blackbody temperature generally decreases with time, the blackbody flux follows the pulse profile, and the thermal flux fraction remains high. Fireball-parameter estimates give a photospheric Lorentz factor of a few hundred and an initial radius of $r_{0}\sim10^{9}$–$10^{10}$ cm, with $1+\sigma_{0}$ of order unity and $\eta\gg1$, supporting a thermally dominated baryonic
outflow. In contrast, EII is dominated by non-thermal emission. Its low-energy
photon indices do not significantly exceed the synchrotron line of death, and the spectra are well described by fast-cooling synchrotron radiation in a decaying
magnetic field. The magnetization constraint gives $\sigma_{\min}\sim1.1$–$4.3$. Since these values exceed unity, they suggest that EII may be Poynting-flux dominated. These results therefore suggest a possible transition in GRB 250920C from a fireball-dominated EI phase to a Poynting-flux-dominated EII phase.
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All authors Jia-Ming Chen, Ke-Rui Zhu, Shan Chang, Dan Zhu, Yu-Lu Gong, Zhao-Yang Peng, Yong-Gang Zheng, Li Zhang
Atmospheric and Oceanic Physics
Boundary-layer scheme selection outweighs microphysics in WRF simulations of the August 2018 Kerala extreme rainfall event
Satyam Kumar, Akshay Sunil and Rashad PE
Because precipitation is regulated by intricate interactions between topography, cloud microphysics,cumulus convection, radiation, and boundary-layer processes, it is still difficult to accurately simulate orographically enhanced monsoon rainfall over the Western Ghats.
Applied Physics
A Predictive Design Framework for a Soft Robotic Ventricle using Contractile Actuators
Jeongmin Kim, Qiong Wang, Liuyang Cheng et al. (+4 more)
The natural cardiac cycle is divided into the systole and diastole phases which encompass four distinct stages: isovolumetric contraction and ejection during systole, followed by isovolumetric relaxation and filling during diastole. Cardiovascular modeling of this cycle ranges from high-fidelity multiphysics simulations to reduced-order lumped-parameter (Windkessel) representation of the heart-artery coupling. However, current models do not relate the mechanics of the actuator driving the ventricle pump to the hemodynamics. In this study, we develop and experimentally validate a predictive design framework for ventricle-like pumps using various types of soft contractile actuators. We build a circulatory loop which reproduces the entire loop including the isovolumetric phases-where pressure changes occur without volume shifts. The framework is based on a lumped-parameter model, hereafter referred to as the phase-dependent Actuator-driven Windkessel 3-element (AWK3) model, to bridge soft actuator mechanics to the cardiac pressure-volume (P-V) loop. Unlike traditional models that require either pressure or volume as a fixed input to estimate the other, our proposed model predicts both variables when informed by the isometric characteristics of the actuators. We validate the model using a ventricle-inspired pump driven by a linear contractile series-elastic actuator or twisted and coiled
polymer actuators (TCPA). We relate the actuator isometric testing protocol to the phase-dependent AWK3 model, which replicates the Frank-Starling law, accurately describing cardiac behavior under varying conditions of preload, afterload, and inotropy (contractility). This approach provides a robust platform for the design and high-fidelity control of bio-inspired soft robotic circulatory systems.
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All authors Jeongmin Kim, Qiong Wang, Liuyang Cheng, Samuel Tsai, Seong Hyeon Kim, Harma K. Turbendian, Sameh Tawfick
Cosmology and Nongalactic Astrophysics
A universal connection between lens density profiles and low-frequency wave optics in gravitational-wave lensing
So Tanaka and Teruaki Suyama
We investigate the low-frequency behavior of the amplification factor in gravitational
lensing and explore how it encodes information about the density profile of the
lensing object. We derive the low-frequency expansion of the amplification factor under the Born approximation for a broad class of projected density profiles. For spherically symmetric profiles that decay faster than any power law at large distances, we derive a systematic expansion of the amplification factor in powers of frequency, with the logarithmic dependence appearing only in the leading term, and show that each expansion coefficient is determined by a finite set of moments of the density profile. We then extend the analysis to profiles with power-law tails and demonstrate that such profiles induce additional non-analytic frequency dependences, including fractional powers and logarithmic terms, which directly reflect the asymptotic behavior of the density distribution. Furthermore, we investigate the effects of non-sphericity and show that contributions from the quadrupole moment appear only as higher-order corrections relative to the spherically symmetric component in the low-frequency regime. Finally, we investigate the validity of the Born approximation in the low-frequency expansion. We derive a criterion for the maximum order of the low-frequency expansion up to which the Born approximation remains dominant over the post-Born corrections.
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Strongly Correlated Electrons
Anomalous Hall Response Induced by Correlated Disorder in the Breathing Kagome Lattice Mn$_{3}$Sn
Tsung-Han Yang, Seng Huat Lee, Hengxin Tan et al. (+10 more)
Macroscopic transport tensors are generally constrained by the average crystallographic and
magnetic symmetries of a material. In the kagome
antiferromagnetic Weyl semimetals Mn$_{3+\delta}X$ ($X=$~Sn or Ge), previous studies showed that the anomalous
Hall conductivity $\sigma_{yx}$ is forbidden by the average \hexsg{} structure and coplanar inverse-triangular
magnetic order. Here we report that nearly stoichiometric Mn$_3$Sn nevertheless exhibits a finite $\sigma_{yx}$ with large hysteresis, together with enhanced $\sigma_{zx}$ and $\sigma_{yz}$, in the inverse-triangular phase below $T_{\mathrm{N1}}\approx 440~\mathrm{K}$, whereas all AHE components vanish in the amplitude-modulated conical phase below $T_{\mathrm{N2}}\approx 280~\mathrm{K}$. Total scattering and
magnetic pair distribution function analysis reveal correlated orthorhombic distortions and noncoplanar Mn moments. First-principles calculations show that this coupled
lattice-
spin distortion activates the average
symmetry forbidden $\sigma_{yx}$ within the inverse-triangular phase. Its disappearance below $T_{\mathrm{N2}}$ indicates that the correlated disorder must cooperate with a long-range inverse-triangular
antiferromagnetic order capable of supporting Berry
curvature. Our results establish correlated disorder as an active
symmetry-breaking degree of freedom that enables topological transport inaccessible from the Bragg-average structure alone.
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All authors Tsung-Han Yang, Seng Huat Lee, Hengxin Tan, Yuanpeng Zhang, Benjamin A. Frandsen, Václav Petříček, Huibo Cao, Daniel Olds, Matthew G. Tucker, Jiaqiang Yan, Binghai Yan, Zhiqiang Mao, Qiang Zhang
General Relativity and Quantum Cosmology
Ovcharenko-Podolsky Einstein-Maxwell gravitational instantons
Hari K. Kunduri
We present an explicit three-parameter family of toric Einstein-Maxwell gravitational instantons. These are complete Riemannian
manifolds with vanishing scalar
curvature which satisfy the Riemannian Einstein-Maxwell equations. We argue that the metric can be extended to a space with two asymptotic ends diffeomorphic to $\mathbb{H}^2 \times S^2$ with a non-collapsing two-cycle (bolt) in the bulk. The global metric is produced by suitably extending an analytic continuation of a local family of Lorentzian black hole geometries constructed by Ovcharenko-Podolsky.
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Quantum Physics
Cascade-induced high-performance nonreciprocal quantum batteries
Niaz Ali Khan and Dahai He
Nonreciprocal
quantum batteries harness reservoir engineering for controlled energy transfer, heralding a paradigm shift for
quantum energy storage. A prior study utilizing the Metelmann-Clerk formalism reported a fourfold enhancement in nonreciprocal energy accumulation over reciprocal counterparts. This fourfold enhancement, however, appears to stem from a Lindblad master equation that exhibits fundamental inconsistencies, which may systematically understate the actual nonreciprocal advantage. Our approach is rooted in the rigorously established cascaded open
quantum systems formalism, which ensures both mathematical consistency and physical fidelity. Remarkably, we surpass the previously reported fourfold
benchmark, attaining a regime-independent sixteenfold steady-state nonreciprocal energy advantage over reciprocal systems. We further uncover a dissipation-dependent battery-to-charger efficiency, fourfold under symmetric damping, surpassing this
benchmark when the battery is less dissipative, and lower otherwise. This work establishes the cascaded formalism as a mathematically rigorous and experimentally viable foundation for high-performance
quantum energy storage.
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Mathematical Physics
Wasserstein Stability, Couplings Across Volumes, and the $1+1/d$ Moment Thresholds in the Edwards–Anderson Model
Mauris Chueng, Hexiang Wang and Keheng Zhu
We study the quenched pressure of the nearest-neighbor Edwards–Anderson Ising model with free and periodic boundary conditions. First, we prove that the infinite-volume pressure is $\beta d$-Lipschitz in the coupling law for the $1$-Wasserstein distance, yielding quantitative thermodynamic limits for spatially inhomogeneous disorder. Second, for periodic volumes, we prove that almost-sure convergence under every joint coupling of the finite-volume disorder arrays is equivalent to complete convergence of the one-volume pressure laws. Third, we prove that $\mathbb{E}\vert{}J\vert{}^{1+1/d}<\infty$ guarantees this universal-coupling conclusion. We further show that this exponent is optimal among uniform power-moment assumptions: for every $1\leq q<1+1/d$, there is a centered symmetric law with finite $q$-th moment for which canonical nested volumes converge almost surely, whereas independently resampled volumes with the same fixed-volume marginals converge in probability but not almost surely. Finally, in dimension one, we prove that the first-moment condition is also necessary for a finite limiting pressure.
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Materials Science
Automated Generation of Commensurate Magnetic Structures based on Spin Space Groups and Graph Theory
Yifan Wang, Boyang Deng, John Robertson et al. (+3 more)
Magnetic structures with
symmetry constraints are candidates for energetically favorable configurations. Enumerating these structures is essential for identifying experimental observations and provides unbiased, linearly stable, and optimally sampled reference configurations for energy fitting when extracting
spin interactions. We present SpinGraph, an automated workflow generating
symmetry-distinct
magnetic configurations. SpinGraph is not only compatible with the more general
spin space groups, but also allows precise control of the prescribed single- or multi-Q states superposition. For finite groups, we enumerate compatible subgroups directly. For
spin space groups with a continuous or special
spin-only part, the finite component is enumerated first and then combined with the compatible exact
spin-only constraints. These actions are translated into graph constraints in real or
Fourier space. The
symmetry of every generated structure is re-evaluated after construction. Finally, we integrate SpinGraph with the
magnetic analysis code AMATIS to perform a thorough calculation for the
spin interactions of the insulating monolayer CrI3. SpinGraph complements the last part of AMATIS and realizes the fully automated workflow for the
spin Hamiltonian construction, which is essential for studying phase transitions,
spin textures,
magnons, and
spin dynamics.
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All authors Yifan Wang, Boyang Deng, John Robertson, Weisheng Zhao, Stefan Blügel, Haichang Lu
Other Condensed Matter
Microscopic Understanding of Thermal-magnon Transport in Low-damping Ferrimagnetic Thin Films
Lerato Takana, Katya Mikhailova, Junwei Tong et al. (+9 more)
Thermally generated
magnons enable heat-driven
spin transport in
magnetic insulators, yet the relative importance of multiple microscopic mechanisms governing their propagation remains incompletely understood. Here, we investigate thermal
magnon transport in low-damping Li$_{0.5}$Al$_{1.0}$Fe$_{1.5}$O$_4$/Pt nanodevices using a nonlocal
spin Seebeck geometry that separates
magnon transport from local thermoelectric effects. Thermal imaging establishes a detector region outside the thermal healing length, enabling intrinsic nonlocal measurements. We find that thermal
magnon transport is strongly suppressed by
magnetic fields far above saturation, and further that thermal
magnon transport decreases with increasing temperature despite an increasing
magnon population. Brillouin light scattering reveals the key microscopic mechanism driving this effect: increasing field reduces the group velocity of backward volume
magnons, directly reducing the
magnon spin diffusion length. Micromagnetic simulations reproduce this behavior only when a temperature-dependent exchange stiffness is included. These results identify
magnon group velocity and exchange stiffness as key parameters governing thermal
magnon transport in ferrimagnetic thin films.
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All authors Lerato Takana, Katya Mikhailova, Junwei Tong, Xiangcheng Liu, Kwangyul Hu, Juan Hofer, Guanxiong Qu, Clare Yu, Ivan Schuller, Michael Flatté, Xiaoqin Li, Yuri Suzuki
High Energy Physics (Phenomenology)
Next-to-Leading-Order Calculation of the Light Tensor $(J^P=2^+)$ Hybrid Correlation Function
R.T. Kleiv, J. Ho, S. Li et al. (+3 more)
We report on the QCD calculations underlying a next-to-leading-order (NLO) QCD Laplace sum-rule analysis of the light tensor $(J^P = 2^+)$ hybrid
meson mass and coupling. This article focuses on the calculation of the NLO perturbative and leading-log NLO non-perturbative contributions. The diagrammatic renormalization method is employed, and a renormalization-group approach is used to determine the leading-log NLO corrections to condensate contributions, including the dimension-six
gluon condensate, whose renormalization we extend to $n_f$
quark flavors. The NLO contributions provide a systematically improved theoretical description of the light tensor hybrid correlation function, leading to more reliable determinations of its mass and coupling. The phenomenological implications of our results are discussed separately in these proceedings.
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All authors R.T. Kleiv, J. Ho, S. Li, S. Narison, T.G. Steele, D. Rabetiarivony
Quantum Physics
Finite Realizations and Effective Memory in Nonlinear Quantum Filtering
Jacob Emerson
Nonlinear dynamics generate non-Gaussian states and operations, but they also make continuously monitored
quantum systems difficult to track. A
quantum filter performs this task by compressing a noisy measurement record into a set of evolving variables that predict future observables. For Gaussian dynamics, this compression is exact and finite. In nonlinear systems, conventional moment equations generally expand without bound, but the failure of one representation does not prove that every finite description is impossible. Here we formulate
quantum filtering as a realization problem for general
quantum input–output maps. We introduce the linearized observable Hankel operator $K_O$, which maps changes in the past measurement record to changes in a future conditional observable. Any finite-dimensional smooth filter forces $K_O$ to have finite rank, so infinite rank provides a coordinate-independent proof that no exact finite-dimensional filter exists. Applied to single-mode
polynomial bosonic systems under continuous quadrature monitoring, this yields a sharp boundary: Gaussian dynamics and the measurement-aligned Conditional Momentum Moment class admit finite realizations, whereas dynamics outside these classes produce infinitely many response directions and admit no finite-dimensional smooth exact filter. Exact impossibility, however, need not imply large practical complexity. The singular values of $K_O$ quantify how many response directions matter at a chosen local accuracy, defining the effective
memory of an observable. For the Kerr and Duffing oscillators, these singular values decay rapidly despite infinite exact rank, showing that infinite exact
memory can coexist with low finite-accuracy complexity. The framework therefore separates exact realizability from effective complexity in nonlinear
quantum filtering.
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High Energy Astrophysical Phenomena
Searching for Type Ia Supernovae in the Dark Energy Spectroscopic Instrument
Xiaoyu Zhuang, Song Ran, Dezheng Meng et al. (+9 more)
With the development of large-scale photometric surveys, an increasing number of
supernova candidates are being discovered, leading to a rapidly growing demand for
supernova spectra. In addition to equipping photometric surveys with follow-up spectroscopic facilities, archival spectra from large multi-object spectroscopic surveys can be mined to provide spectroscopic classifications for candidates and to find
supernovae missed by previous surveys. In this work, we combine Principal Component Analysis (PCA), the Local Outlier Factor (LOF)
algorithm, and the
supernova classification tool SNID to search for Type Ia
supernovae among 1,757,303
galaxy spectra from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 (DR1). We finally obtain 247 Type Ia
supernovae and 17
supernovae of other types. Among these, 202
supernovae lack classification records in the Transient Name Server (TNS) and represent newly identified SNe. These results demonstrate the potential of multi-object spectroscopic surveys to supplement
supernova samples, particularly for transients missed by traditional photometric surveys.
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All authors Xiaoyu Zhuang, Song Ran, Dezheng Meng, Weiyu Ding, Ranfang Zheng, Yao Yao, Zheyu Lin, Bingxue Fu, Fujia Li, Zelin Xu, Jie Song, Xu Kong
Applied Physics
Round-the-Clock Sub-Ambient Cooling via Dynamic Sky View Factor Steering
Qiuyu Chen, Minghao Dong, Zheng Zhang et al. (+3 more)
Passive daytime radiative cooling holds significant potential to address sustainability challenges such as the energy-water nexus. However, common static horizontal configurations cannot respond to dynamic changes of environmental conditions such as
solar position and cloud coverage, thereby forfeiting the opportunity of optimizing the cooling performance in the 24-h day-night cycle. Here, inspired from the heliotropism of sunflowers, we develop a dynamic sky view factor steering (DSVFS) system. By dynamically steering the emitter to an optimal angle, this system not only relaxes the stringent dual requirement of ultra-high
solar reflectivity and infrared emissivity of the radiative emitter, but also maximizes its cooling power round-the clock. Using this DSVFS system, we experimentally demonstrate sub-ambient cooling during a typical hot noon even with a near-blackbody emitter; with a selective emitter, we demonstrate an increase of cooling power by 135% as compared to its static counterpart. Case studies of multiple cities across the world indicate a maximum annual electricity saving of up to 200 kWh/m^2.
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All authors Qiuyu Chen, Minghao Dong, Zheng Zhang, Xiaodonog Zhao, Peng Xiao, Zhen Chen
High Energy Astrophysical Phenomena
Pulse Signal Simulation of Pulsars
Jalormi Brahmachari and Mayuresh Surnis
The present thesis is a work in progress on improving the simulation of integrated pulse profiles of
pulsars.
Pulsars, highly magnetized rotating
neutron stars, serve as precise
cosmic clocks useful for studying
gravity and the interstellar medium. Although periodic pulses from many
pulsars are observed and modeled at differ- ent
radio frequencies, a robust realistic simulation of their profiles utilizing their parameters remain underdeveloped. The present study focuses on developing a physically consistent model to reproduce observed pulse shapes across multiple frequencies. This study will be useful in coherently understanding the various as- pects of the
pulsar emission mechanism. These integrated pulse profiles are the time-averaged properties of
pulsar emission and are obtained after averaging indi- vidual pulses over a few thousand rotations. Observed to be highly stable, these are indicative of the global properties of the
pulsar magnetosphere. By refining simulation techniques and incorporating the propagation effects of the interstellar medium, this work will prove to be helpful in generating synthetic, yet realistic models. The results are expected to contribute to the interpretation of observa- tional data and to the development of improved timing and emission models for
pulsars
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Quantum Physics
Perfect State Transfer from a Localised Two-Excitation State to a Dicke State via Static Spin-Network Hamiltonians
Soumyojyoti Dutta
I construct a family of time-independent, excitation-preserving
spin Hamiltonians realising perfect state transfer from a localised two-excitation state to the symmetric two-excitation Dicke state, for every $N\ge4$. The
Hamiltonian has the physical form $H=\sum_{i<j}J_{ij}(\sigma_i^+\sigma_j^-+\sigma_j^+\sigma_i^-)+\sum_i\epsilon_i n_i$ with real couplings, and satisfies $e^{-iHt}|110\cdots0\rangle=e^{i\phi}|D_N^{(2)}\rangle$ at a finite time. An $S_{N-2}$ permutation
symmetry on the unoccupied
spins reduces the dynamics to a four-dimensional invariant subspace. Requiring $(|\psi_0\rangle+|D_N^{(2)}\rangle)/2$ to be a zero eigenvector fixes the on-site energies in closed form and leaves three coupling parameters free. The inverse spectral problem then becomes two
polynomial equations in two coupling ratios; eliminating one gives a degree-six reciprocal
polynomial, which $z=x+x^{-1}$ converts to a cubic. For the spectral family $(-n,-1,1)$ with odd $n$, factorising the cubic's leading coefficient and evaluating it at $z=-2$ shows that some odd $n$ always produces a real root below $-2$, which a subresultant lifts back to the original system. The existence argument is symbolic and uses no numerical optimisation. Since that coefficient contains no odd powers of $n$, the required $n$ comes with an explicit threshold, not an asymptotic guarantee. I also cost the construction: couplings grow as $N^{1/2}$ and the on-site range as $N^{3/2}$, the transfer time stays within a factor 2.3-3.0 of the Mandelstam-Tamm limit at every size, and the fidelity is sensitive to systematic drift of the spectator-spectator coupling class but tolerant of independent bond disorder, which self-averages. This is a constrained analogue of perfect state transfer: for general real states an unconstrained real symmetric
matrix suffices, whereas here the
Hamiltonian must have excitation-preserving
spin-network form.
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Plasma Physics
A polar-harmonic unified gas-kinetic scheme for magnetized ion dynamics from cyclotron kinetics to the Hall-Pedersen constitutive limit
Yixiao Wang, Zhigang Pu, Xing Ji et al. (+1 more)
Magnetized ion transport in weakly ionized
plasmas ranges from gyroangle-dependent kinetics to
Hall-Pedersen drift-
diffusion as collisionality and magnetization vary. We develop a polar-harmonic unified gas-kinetic scheme (PH-UGKS) for the ion Vlasov-BGK equation in a uniform
magnetic field. The scheme evolves the full ion distribution by coupling a conservative density update to exponential
evolution of its nonequilibrium component. Exact collision-rotation integration in gyroangle
Fourier space is combined with a time-averaged kinetic flux that incorporates spatial transport and electric acceleration, together with a compact
Hall-Pedersen correction to the density flux. The scheme conserves ion number, and analysis establishes second-order temporal consistency and asymptotic preservation of the
Hall-Pedersen density limit at fixed magnetization. Numerical tests reproduce ion Bernstein dispersion and Dory-Guest-Harris growth rates and resolve changes in the gyroharmonic spectrum as the collision-to-gyrofrequency ratio varies. The driven ion-flux response agrees with an independent characteristic-Volterra reference, including finite-frequency departures from the instantaneous
Hall-Pedersen relation. In collisional tests, accurate responses are obtained with time steps far larger than both the collision time and the gyroperiod. Fixed-resolution density tests confirm convergence to the corresponding
Hall-Pedersen discretization. The same kinetic formulation thus connects kinetic response and macroscopic transport without switching to a fluid solver or subcycling microscopic time scales.
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All authors Yixiao Wang, Zhigang Pu, Xing Ji, Kun Xu
Soft Condensed Matter
Geodesic Trapping and Escape of Active Particles on Curved Surfaces
Yuzhu Chen, Vishal P. Patil and David Saintillan
Active particles on curved surfaces can become trapped along closed geodesics even without physical barriers. We show that escape from these
geometric traps exposes a fundamental distinction between continuous and discrete reorientation. At high Péclet numbers, active Brownian particles escape efficiently through rotational
diffusion, whereas run-and-tumble particles remain trapped much longer; at low Péclet numbers, both reduce to passive
diffusion. Gaussian
curvature controls escape by focusing or defocusing neighboring geodesics, producing distinct asymptotic scalings of the mean exit time.
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Astrophysics of Galaxies
High Resolution Spectroscopic Follow-up Observation Results for 13 EMP Candidates Selected by Narrow-band Photometry
Huiling Chen, Yang Huang, Huawei Zhang et al. (+1 more)
Extremely metal-poor (EMP; [Fe/H] < -3.0)
stars preserve key information about the earliest stages of
Galactic chemical
evolution. Based on a training set of spectroscopic
metallicities, we constructed catalogs of more than 120,000 EMP candidates from large-scale narrow-band photometric surveys. To validate this approach, we obtained high-resolution CFHT/ESPaDOnS spectra for 13 candidates selected from the SkyMapper-based catalog. The follow-up observation confirms that the narrow-band photometric selection is effective in identifying very metal-poor
stars and retaining a substantial EMP fraction: four targets are confirmed as EMP
stars, and all targets remain very metal-poor with [Fe/H] < -2.4. The photometric
metallicities are systematically lower than the spectroscopic values by 0.44 dex, with a relatively small scatter of 0.19 dex, indicating a systematic offset in the photometric
metallicity scale that could be reduced through improved calibration. Abundances for more than 20 chemical species are derived, leading to the identification of a new potassium-enhanced r-II
star, J2001-1215. By combining chemical abundances with orbital properties, five
stars are found to be dynamically consistent with known
Galactic substructures, including
Gaia–Sausage–Enceladus, Thamnos, and Sequoia. These
stars provide high-resolution chemical measurements for the extremely metal-poor regime of these
Galactic substructures. These results underscore the role of narrow-band photometry in efficiently selecting EMP candidates for targeted high-resolution spectroscopic follow-up, thereby enabling detailed chemical and dynamical studies of the early Milky Way.
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All authors Huiling Chen, Yang Huang, Huawei Zhang, Zhen Guo
Mathematical Physics · Cross-listed from math.PR
Sharp Typical Distance and Exponential Small-Ball Bounds in One-Step-Cliff Nielsen Geometry
Honghuai Fang
Let $D=2^n$ and equip $\operatorname{PU}(D)$ with the one-step-cliff Nielsen metric, with quadratic metric coefficients one in Pauli directions of weights one and two and $D^2$ in all higher weights. We prove that the distance from the identity of a Haar-random element, normalized by $D$, converges to $\pi/\sqrt3$ in probability and in $L^p$ for every $1\le p<\infty$. Quantitatively, it lies within $O(D^{-1/8}(\log D)^{1/2})$ of this limit outside a set of Haar measure at most $\exp\{-\Omega(D^{7/4}\log D)\}$. For each fixed $0<x<\pi/\sqrt3$, the ball of radius $xD$ has Haar measure $\exp\{-\Theta_x(D^2)\}$; for $x>\pi/\sqrt3$, its complement has measure at most $e^{-c_xD^2}$ for some $c_x>0$. As $x\uparrow\pi/\sqrt3$, the lower and upper logarithmic rates are both asymptotic to $(\pi^2/3-x^2)^2/(16\zeta(3))$. The small-ball upper bound follows from a comparison of Jacobi determinants, obtained by rescaling the linearized geodesic equations and applying Kato transport. Weyl integration reduces the remaining integral to an Abel-regularized logarithmic-energy estimate on the circle. A centered principal logarithm and concentration of the circular
unitary ensemble eigenangle second moment give the distance upper bound.
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Instrumentation and Detectors
Spectral Discrimination of Deposited Gamma-Ray Energies in a Simulated CeBr$_3$ Scintillator
Andrey Elagin
We show that wavelength measurements of individual detected optical
photons may provide additional information about gamma-ray energy deposited in a CeBr$_3$
crystal when the detected-
photon-count distributions overlap for nearby gamma-ray energies. Monoenergetic 662 and 629 keV gammas are used in a Geant4 simulation of a $25\times25\times20~\mathrm{mm^3}$ CeBr$_3$
crystal. Assuming a light yield of $6.0\times10^4$
photons/MeV, a wavelength-independent
photon-detection efficiency of 30%, and a wavelength resolution of $\sigma_{\lambda}=40$ nm, we find that the fraction of
photons reconstructed above 385 nm gives an event-level separation of $\sim$ 2 standard deviations between the 662 and 629 keV event populations selected within the same $\sim$ 1%-wide detected-
photon-count interval. No timing or reconstructed interaction-position information is used. The result demonstrates, within the present simulation model, that event-dependent optical spectra can retain energy information beyond an undifferentiated
photon count.
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Mathematical Physics
Counterexamples to GNS Conjecture 1.8
Xiuqing Duan
We disprove both parts of
Conjecture 1.8 of Gabrielov, Novikov, and Shapiro (GNS). For the Coulomb potential, a generic rational configuration of 24 unit charges in $\mathbb{R}^3$ has at least 18 nondegenerate critical points of Morse index one but exactly 14 effective Voronoi one-
cells. A separate proper-line construction has at least two nondegenerate minima but only one relatively effective zero-dimensional
cell intersection. For each positive subspace dimension, product suspension gives a proper-subspace counterexample.
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