Astrophysics of Galaxies
A sub-100 pc view at z~5 of a Multiply-Imaged Massive Quiescent Galaxy
Richard Pan, Danilo Marchesini, Joseph F. V. Allingham et al. (+34 more)
Recent James Webb Space
Telescope spectroscopic surveys reveal an abundance of rapidly assembled early
galaxies in the first billion years. Cosmological simulations struggle to reproduce this population because models require a rapid, highly efficient conversion of
baryons into
stars followed by an abrupt cessation of
star-formation, known as quenching, in the early Universe. Testing these theoretical models remains difficult because high-
redshift field
galaxies appear compact and unresolved. This lack of resolution makes it impossible to distinguish compaction-driven quenching from secular
evolution. Here we present VENUS-CLJ0152-QG1, a massive post-starburst
galaxy at $z=5.18\pm0.15$, with inferred low-levels of
star-formation in the last 30 Myr. The foreground cluster CL J0152.7-1357 gravitationally lenses the system into three images with median magnifications of $\mu \sim$ 7, 11, and 0.6. This geometry yields a physical resolution of $\sim 70$ pc, a factor of $\sim 7$ better than the JWST/NIRCam fundamental blurring limit (full-width half-maximum of $\sim$0.48 kpc at $z\sim5$). Our two-dimensional mapping reveals a half-light radius twice as large as expected, a central
stellar mass surface density half a dex lower than field analogs, and off-center ionized gas emission. Together, these features show that VENUS-CLJ0152-QG1 abruptly ceased
star formation in the absence of a compaction event or an obvious active
galactic nucleus. Consequently, this
galaxy shows that unresolved observations likely overestimate the global densities of early
galaxies, and that theoretical models require alternative pathways to quench massive sources without relying on compaction or unobscured AGN.
Read the full abstract ▾
All authors Richard Pan, Danilo Marchesini, Joseph F. V. Allingham, Seiji Fujimoto, Adi Zitrin, Dan Coe, Vasily Kokorev, Lukas J. Furtak, Jacqueline Antwi-Danso, Yoshihisa Asada, Franz E. Bauer, Maruša Bradač, Larry D. Bradley, Chloe M. Cheng, Pratika Dayal, Andreas L. Faisst, Brenda L. Frye, Norman A. Grogin, Tiger Yu-Yang Hsiao, Gourav Khullar, Anton M. Koekemoer, Conor Larison, Ray A. Lucas, Vladan Markov, Nicholas S. Martis, Minami Nakane, Gaël Noirot, Johan Richard, Massimo Ricotti, Luke Robbins, Fengwu Sun, Francesco Valentino, Eros Vanzella, Chris Willott, Rogier A. Windhorst, Hiroto Yanagisawa, Anita Zanella
Quantum Physics
Compressed Permutation Oracles Revisited
Joseph Carolan and Christian Majenz
The compressed permutation oracle has been used to analyze the
quantum security of a number of cryptographic constructions which resisted prior techniques. However, these analyses were fundamentally limited by the poor soundness of the method: the technique was proven sound only up to $O(N^{1/12})$ queries to permutations on $N$ elements. We revisit this analysis, improving the soundness bound to a tight $\Omega(N^{1/2})$. In addition to being tighter, our proof is conceptually simpler and more direct, and gives the same bound in the ideal cipher model. The main technical idea is to construct the compression isometry from a simple POVM on the naive purification, a technique which may find wider applications. As immediate applications, our results yield tight, concrete collision and pre-image lower bounds for the sponge hash construction underlying SHA3 and the Davies–Meyer compression function used in SHA1 and SHA2. More broadly, the improved soundness
theorem provides a general-purpose tool for analyzing
quantum security in settings where random permutations or ideal ciphers serve as the underlying primitive.
Read the full abstract ▾
Instrumentation and Detectors
Fast-Neutron Scintillation with Multi-Quantum-Well 2D Perovskites
Shaun Tan, Zachary Benesh, Seong Eui Chang et al. (+4 more)
Fast-
neutron scintillators must efficiently convert
neutron energy into detectable light while enabling selectivity between
neutrons and the {\gamma}-ray background. Here, we report a synthesis strategy for layered two-dimensional (2D) lead halide perovskite scintillators with independent control of the macroscopic detector geometry and microscopic phase composition. Our synthesis approach produces mm-thick, large-area scintillators with a deliberately engineered multi-
quantum-well energy landscape, creating an effective spectral separation while retaining nanosecond emission dynamics. Our scintillators exhibit an energy resolution of 5.4% at 662 keV under 137Cs irradiation. Under deuterium-deuterium fusion
neutron irradiation, we directly demonstrate
neutron and {\gamma}-ray event separation by pulse shape discrimination, with a figure of merit of 3.51. Taken together, these results establish multi-
quantum-well 2D perovskites as a scalable materials platform that combines fast-
neutron sensitivity and selectivity within a controllable detector form factor.
Read the full abstract ▾
All authors Shaun Tan, Zachary Benesh, Seong Eui Chang, Shelby Elder, Haidi Jakovic, Tae-Woo Lee, Moungi G. Bawendi
Quantum Physics
Purely-logarithmic-time- and constant-space-overhead fault-tolerant quantum computation
Zhengyi Han and Zi-Wen Liu
We prove that constant-space-overhead fault-tolerant
quantum computation can be achieved with provably strictly logarithmic time overhead, improving over the best known results with additional subpolylogarithmic factors. Our main construction uses
polynomial-subrank transversal logical $\CCZ$ gates on good
quantum locally testable codes to implement addressable universal computation by transferring batches of logical
qubits between dense storage and active logical subspaces while reusing the same ancillary workspace. Logical $\CCZ$ gates are implemented directly by the transversal operation, so only stabilizer resource states require separate preparation. Furthermore, we give an alternative construction that also achieves purely logarithmic time overhead based on modifying the
quantum Reed–Solomon magic-state
distillation scheme of Nguyen and Pattison. Recursively applying a fixed
distillation circuit protected by qLTCs of increasing block length eliminates the subpolylogarithmic time factor.
Read the full abstract ▾
High Energy Astrophysical Phenomena
First Pre-peak Ultraviolet Spectrum of a Tidal Disruption Event: A Fast Outflow Revealed Prior to Maximum Light in TDE2025aarm
Erica Hammerstein, Ryan Chornock, Jean Somalwar et al. (+32 more)
The
tidal disruption and eventual
accretion of a
star by a massive black hole can lead to the launching of
outflows and winds that encode important information about the
tidal disruption and
accretion processes. However, little is known about the existence and behavior of these
outflows before optical light-curve peak, when processes such as stream-stream collisions and disk formation may be important. Here, we present the first pre-peak ultraviolet (UV) spectrum of a
tidal disruption event (TDE), obtained $\sim 20$ days before optical maximum light of the nearby (
redshift $z=0.0137$) TDE2025aarm, along with quasi-simultaneous infrared (IR) through X-ray observations. Our HST/STIS spectrum shows strong evidence for an early-time
outflow through broad near-UV (NUV) and far-UV (FUV) absorption lines blueshifted by $\sim$10,000 km s$^{-1}$, including two new UV broad absorption features not yet identified in a TDE. We find that the FUV–IR continuum deviates significantly from a blackbody ($f_\lambda \propto \lambda^{-3.08}$), which we interpret as a signature of reprocessing through the
outflow. This deviation implies that the bolometric luminosity in optical TDEs may be underestimated by a significant factor ($\sim$9 in this case) when inferred from single-temperature blackbody fits to NUV–optical photometry alone. This work further confirms that TDEs are capable of launching fast
outflows at very early times and emphasizes the importance of
prompt FUV spectroscopic observations of TDEs that can capture the full continuum emission and energetics.
Read the full abstract ▾
All authors Erica Hammerstein, Ryan Chornock, Jean Somalwar, Raffaella Margutti, Brenna Mockler, Olivia Aspegren, Itai Sfaradi, Natalie LeBaron, Jonathan Carney, Alexei V. Filippenko, A.J. Nayana, Igor Andreoni, Thomas Brink, Peter J. Brown, Adam J. Burgasser, S. Bradley Cenko, Suvi Gezari, Xiaoshan Huang, Mansi M. Kasliwal, Jon M. Miller, Sasha Mintz, Sam Rose, Peter Senchyna, Joshua D. Simon, Emma Softich, Robert Stein, Yuhan Yao, WeiKang Zheng, Richard Dekany, Matthew J. Graham, Russ R. Laher, Josiah Purdum, Ben Rusholme, Jesper Sollerman, Stefan van der Walt
Instrumentation and Methods for Astrophysics
Differentiable astrophysics at scale: solving and differentiating ODE ensembles on the GPU
A. Spurio Mancini
Astronomers increasingly fit their models with gradient-based methods, such as
Hamiltonian Monte Carlo, which need the derivatives of the model with respect to its parameters. In many analyses a prediction requires solving a small system of ordinary differential equations (ODEs) for thousands to millions of parameter sets, and this ensemble of integrations often sets the cost of the analysis. We introduce to the astronomical community GRADSOLVE, a JAX library that moves this computation to graphics processing units (GPUs): it integrates each member of the ensemble in its own GPU thread with its own step size and returns the derivatives with respect to the parameters in the same pass. We measure the speed-up it provides in three examples from different fields of astronomy,
stellar orbits in the
Galactic potential, the expansion history of a dark-energy cosmology and the
spin precession of binary black holes, with every code held to the same accuracy requirement. For a million trajectories GRADSOLVE runs 8.5 to 1500 times faster than the serial CPU code of each example running on all 128 cores of a CPU, and several orders of magnitude faster than on one core. On the same GPU it is also 11 to 15 times faster than DIFFRAX, the state-of-the-art ODE library in JAX, in all three examples. With GRADSOLVE a million such integrations take seconds or less on one GPU, so gradient-based analyses that need ensembles of this size become routine. The code is publicly available at https://github.com/ECLIPSE-AI4Science/gradsolve.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Sterile Neutrino Dark Matter Cries for GeV Heavy Neutral Leptons
Marco Drewes, Yannis Georis, Juraj Klarić et al. (+2 more)
The ordinary and dark matter in the Universe may share a common origin in the framework of a minimal extension of the Standard Model by three right-handed
neutrinos. A pair of such heavy neutral
leptons (HNLs) can give masses to
neutrinos, generate the
baryon asymmetry at the electroweak scale and produce a large
lepton asymmetry at the QCD scale, which is then resonantly transformed into an abundance of the third state that acts as sterile
neutrino dark matter. The minimality of this setup, known as
Neutrino Minimal Standard Model ($\nu$MSM), makes it highly predictive. Earlier attempts to pin down the properties of the HNLs based on the requirement to simultaneously explain the
neutrino masses as well as the baryonic and dark matter abundances were hampered by an incomplete understanding of the
quantum kinetic equations describing the HNLs throughout
cosmic history. We perform the first parameter scan of the $\nu$MSM in which this shortcoming has been overcome. We find that the $\nu$MSM provides a common explanation for all aforementioned phenomena only within a well-defined parameter space that is limited in all directions, with HNL masses kinematically accessible by the SHiP experiment as well as searches at the LHC and future
lepton colliders. Further predictions for the HNL decay branching ratios, CP-violation, and
lepton number violation (LNV) make the model highly testable, bringing a discovery of the common origin of
neutrino masses and all matter in the Universe within reach of existing and planned experiments.
Read the full abstract ▾
All authors Marco Drewes, Yannis Georis, Juraj Klarić, Mikhail Shaposhnikov, Inar Timiryasov
High Energy Physics (Theory)
Scalar Gauss-Bonnet Wormholes and the Imaginary Distance Bound
Alex Kehagias and Antonio Riotto
We study $O(4)$ symmetric Euclidean wormholes in four-dimensional
gravity with a massless scalar linearly coupled to the Gauss-Bonnet invariant. At nonzero coupling, the Einstein wormhole becomes a regular complex saddle that satisfies the Kontsevich-Segal-Witten criterion until its branch ends at a finite coupling. In asymptotically flat space, the Gauss-Bonnet term modifies the scalar displacement and the on-shell action for finite wormholes, but the size dependent parts of both corrections vanish in the large throat limit. The original imaginary distance threshold therefore remains unchanged. A negative cosmological constant already lowers the Einstein large throat imaginary distance relative to its flat space value. When the Gauss-Bonnet coupling is also present, the scalar is no longer a modulus as it develops a logarithmic running and its trajectory has infinite length. Subtracting the logarithmic asymptotic behavior leaves a finite regulated displacement. Its large throat value is shifted upward from the Einstein AdS result by the Gauss-Bonnet interaction and determines the leading large charge behavior of the renormalized fixed charge action.
Read the full abstract ▾
Materials Science
Altermagnetism and generalised tensorial properties in the exchange multiplet framework
Paolo G. Radaelli
A representation-theoretic framework for the calculation of time-reversal-odd tensorial properties of
magnetic materials based on the Bertaut–Izyumov exchange-multiplet formalism is developed. In contrast to approaches based on distinct
magnetic point groups or
spin groups for different orientations of the
magnetic order parameter, the exchange-multiplet framework permits the order parameter to be treated as a continuous variable. It is shown that, for constant-moment collinear structures, covariance imposes a simple set of
symmetry constraints on the tensor intertwiners appearing in a Landau–Lifshitz expansion. This leads to canonical intertwiner forms that factorise the
magnetic and crystallographic parts of the tensor construction. Tensor fields can be built to retain a Cartesian representation in the physical variables while acquiring a systematic dependence on the order-parameter direction through
symmetry-adapted
polynomial bases.
Magnetic-point-group selection rules are recovered automatically for arbitrary order-parameter directions, while the framework also provides a natural separation of co-rotating (SOC-free) and non-co-rotating contributions. The approach is applicable to altermagnets and conventional antiferromagnets alike and is particularly suited to experiments and first-principles calculations in which the
magnetic order parameter can be continuously varied.
Read the full abstract ▾
Optics
Spatial-Spectral Trade-offs in Metasurface-Based Snapshot Hyperspectral Imaging
Liam Fitzpatrick, Sean Molesky and Kai Wang
Snapshot hyperspectral imaging maps a spatial–spectral datacube onto a two-dimensional detector, with recoverability depending on the datacube sampling regime, the scene prior, and the optical encoding. We study this co-dependence with algorithmic recovery and optical design optimization in a differentiable metasurface model by varying the spatial–spectral ratio and comparing average-coherence, mutual-information, and end-to-end objectives. For compressed imaging with three bands, optimization of single-parameter dielectric pillars produces lens-like designs with overlapping wavelength-dependent point-spread functions across the objectives tested. End-to-end reconstruction can mask this collapse on restricted training distributions, showing that reconstruction fidelity depends jointly on the optical encoding and scene prior. For simple nano-pillar meta-atom geometries, the optimized singular-value spectrum deteriorates as the datacube becomes more spectrally dominated, whereas a relaxed model with independent complex transmission at each wavelength reduces this dependence. These results identify restricted wavelength-dependent transmission control in the pillar library as an important contributor to the observed spectral collapse. This motivates an illustrative local super-pixel spectrometer model in which spectral encoding is studied separately from global image formation under a plane-wave illumination approximation.
Read the full abstract ▾
Disordered Systems and Neural Networks
Nonequilibrium Phases of Repulsive Self-Attention: Chaos, Attention Condensation, and Emergent Locality
Qucheng Gao, Zuyi Yang and Xiao Chen
We study the nonequilibrium dynamics of a minimal recurrent
transformer with $N$ normalized
tokens, $Q=K=I$, and a negative value map $V=-I$. Similarity-based
attention selects nearby representations, while the negative value map drives
tokens away from the selected field. This feedback can continually reorganize both the representation geometry and the
attention network. For $d=2$, the
tokens lie on a circle, where the regular polygon is an exact fixed point. As the
attention feedback strength $\gamma$ is increased, the polygon loses stability through a flip bifurcation, giving rise to period-two motion, chaos, and cluster-exchange or cluster-flip states. Despite this temporal complexity,
attention remains diffuse as $N\to\infty$ at finite fixed softmax sharpness $\beta$.
Attention condensation instead emerges in the scaling regime $\beta\sim N^2$. In the hard-routing limit, repulsive updates amplify local perturbations and routing-partner switches transmit them ballistically, producing an emergent butterfly cone in representation space. High-dimensional geometry provides a distinct route to localization. For $d=N\to\infty$, simulations from Gaussian initial conditions provide evidence for a condensation transition at $\beta=O(1)$, driven by dynamically generated finite overlap gaps. Depending on $\gamma$, the resulting phases include diffuse simplex-like states, consensus flips, condensed active routing with signatures of chaos, and fragmented cluster flips. These results establish temporal activity,
attention condensation, and
geometric clustering as distinct collective phenomena, and show that sparse
attention can sustain persistent dynamics rather than freeze it.
Read the full abstract ▾
Superconductivity
Field-induced incipient spin-density phase stabilized inside the nematic phase of FeSe$_{1-x}$S$_x$
I. Paulescu, R. M. Abedin, J. S. Pearce et al. (+8 more)
Spin-density wave (SDW) order and superconductivity frequently compete and coexist in unconventional
superconductors, where
spin fluctuations often mediate superconducting pairing. In iron-chalcogenide
superconductors, FeSe$_{1-x}$S$_x$, SDW order has only been detected under applied pressure, while both
spin and nematic fluctuations are involved in determining their rich superconducting phase diagrams. Here, we report evidence for an incipient SDW phase, within the nematic state of FeSe$_{1-x}$S$_x$, revealed in
magnetic fields up to 68~T. Once superconductivity is quenched, we observe sharp upturns in longitudinal resistivity accompanied by anomalies in tunnel diode oscillator frequency response and torque anisotropy, consistent with a field-induced electronic order. Dominant low-frequency
quantum oscillations reveal a small reconstructed
Fermi surface, consistent with a field-induced SDW order. Direct experimental comparisons with a pressure-tuned nematic, analogue, FeSe$_{0.96}$S$_{0.04}$, demonstrate that SDW phases are stabilized within the nematic phase of FeSe$_{1-x}$S$_x$ via both chemical substitution and applied pressure. These findings reveal that by weakening nematicity, the SDW orders are stabilised, which promotes the dominant superconducting pairing mechanism in iron chalcogenides.
Read the full abstract ▾
All authors I. Paulescu, R. M. Abedin, J. S. Pearce, W. H. Fong, Z. Zajicek, A. Morfoot, W. Knafo, O. Squire, D. Graf, A. A. Haghighirad, A. I. Coldea
Strongly Correlated Electrons
Angular Modulations in Magnetic Torque Induced by Phase Transitions in the Triangular Supersolid $2H$-AgNiO$_2$
John S. Pearce, Zeyu Ma, Alimamy Bangura et al. (+4 more)
Easy-axis frustrated triangular
lattice antiferromagnets provide an important playground for stabilising a wide range of exotic
magnetic phases. The delafossite $2H$-AgNiO$_2$ offers a unique model system containing a
lattice of localised ($S=1$) moments surrounded by a honeycomb of itinerant electrons. Below $T_{\rm N} =19$ K, the system exhibits collinear stripe
antiferromagnetic order, whereas applied
magnetic fields induce a cascade of transitions which has been proposed to contain a
magnetic supersolid phase. In this study, we perform detailed angular and field-dependent torque measurements in static fields of up to 45~T on single
crystal samples. The angular dependence of the torque displays a sawtooth-shaped signal close to the first supersolid phase, while near $T_{\rm N}$, an unexpected additional modulation emerges. On the other hand, the field dependence of the torque indicates the presence of four field-induced anomalies which evolve in distinct ways as a function of field orientation. To understand these complex behaviours and assess the role of local moments, we employ mean-field and Monte-Carlo calculations on a minimal
spin model and construct comprehensive polar phase diagrams at different temperatures. We find that the angular dependence of the torque can be understood in terms of crossing different phase boundaries by field rotation, and we identify qualitative similarities between the experimental and theoretical polar phase diagrams. Our study highlights $2H$-AgNiO$_2$ as a rich anisotropic system that provides a robust example of how
spin supersolid orders can manifest in angle-dependent
magnetic torque.
Read the full abstract ▾
All authors John S. Pearce, Zeyu Ma, Alimamy Bangura, Timo Sorgel, Martin Jansen, Radu Coldea, Amalia I. Coldea
Quantum Physics
Analog neutral-atom for in-memory processing in quantum reservoir computing
Luca Nigro, Gian Luca Giorgi, Enrico Prati et al. (+1 more)
Quantum Reservoir Computing (QRC) exploits the rich dynamics of
quantum many-body systems to process time-dependent information with high-dimensional state spaces. While neutral atom arrays offer a scalable platform for this paradigm, realizing intrinsic temporal
memory without relying on external classical buffering requires precise control over the relaxation dynamics of the system. We address the necessity of specific non-
unitary dynamics for enforcing fading
memory while overcoming the lack of separability. This study simulates and empirically identifies the specific dynamical regimes required to maximize the computational capacity of the reservoir, addressing the amount of dissipation, the effectiveness of lying at the edge of
quantum chaos, and that of time-multiplexing compared to the scaling of the physical size of the system. Here we show that controlled dissipation is strictly necessary to induce echo state property, fading
memory, and separability, in neutral atom arrays. Computational performance increases at the edge of
quantum chaos. The counter-intuitive residual
memory provided by the unital phase damping channel is justified by introducing a model based on pure outputs. The consequent implementation enables the solution of complex non-linear tasks, such as the Mackey-Glass time series, with as few as $N=5$ atoms. We establish a rigorous framework for engineering dissipative
quantum reservoirs required for intrinsic temporal processing on near-term
quantum devices.
Read the full abstract ▾
All authors Luca Nigro, Gian Luca Giorgi, Enrico Prati, Roberta Zambrini
Quantum Physics
Sharp pairwise reduction for quantum hypothesis testing
Kuan-Yi Lee and Ludovico Lami
We determine the optimal universal coefficient in a reduction of multiple to binary
quantum hypothesis testing. Specifically, for every finite ensemble in any
Hilbert space dimension (finite or infinite), we prove that the error probability of the global pretty good measurement (PGM) is at most four times the sum of the optimal binary error probabilities. By constructing a family of regular-simplex ensembles, we further show that the coefficient four is optimal, even for arbitrary global measurements. This result improves on the pairwise bounds established by Cheng and Liu [arXiv:2606.06246 (2026)] and entails an explicit, sharp guarantee for the standard PGM itself. Our proof is also simpler: rather than constructing sequential measurements and applying a union bound, our proof relies on purely
matrix-analytic techniques, combining a direct block Gram
matrix analysis of the PGM error and a refined inequality between
quantum Hellinger distance and Bures $\chi^2$-divergence. Our analysis also yields a refined, one-shot pairwise Chernoff bound and explicit sufficient number of copies for a desired discrimination error.
Read the full abstract ▾
Strongly Correlated Electrons
Cooperative Domain-Wall Dynamics in a Two-Dimensional Quasiclassical Holstein Model
Arunangshu Bora, Sankha Subhra Bakshi, Ho Jang et al. (+1 more)
We investigate charge-density-wave (CDW) coarsening in a two-dimensional quasiclassical Holstein model following thermal quenches into the ordered phase. Although the staggered CDW order parameter is nonconserved, domain-wall motion remains constrained by conservation of the microscopic electronic charge. The simulations exhibit apparent growth exponents between $1/4$ and the Allen–Cahn value $1/2$. These apparent exponents are primarily accounted for by the crossover kinetics $\dot{L}=[D(T)/L][1+L_\times^2(T)/L^2]$, where $L_\times(T)$ is a temperature-dependent crossover length. At low temperature, nearly binary occupations require compatible wall segments to rearrange cooperatively, producing the $L(t)\sim t^{1/4}$ limit. Thermal broadening creates partially occupied interfacial sites that permit local
curvature-driven motion and restore $L(t)\sim t^{1/2}$ at late times. Fits to the measured growth rate, a dimensionless rate collapse, and a long-time large-system simulation consistently support this crossover picture. These results show that a microscopic conservation law can generate long-lived anomalous coarsening even when the emergent order parameter is nonconserved.
Read the full abstract ▾
All authors Arunangshu Bora, Sankha Subhra Bakshi, Ho Jang, Gia-Wei Chern
Physics and Society
Transfer Dynamics and Spectral Cascades in Graph-Coupled Kuramoto Networks
Marcin Kowalczyk, Pietro Liò and Zbigniew R. Struzik
This work introduces a spectral transfer formalism for nonlinear synchronisation dynamics to resolve how internal dynamical activity redistributes across network scales, moving beyond traditional global observables like the Kuramoto order parameter. By projecting Kuramoto phase dynamics onto the eigenbasis of the graph
Laplacian, we construct a time-dependent transfer
matrix and derive novel network metrics, including the spectral flux, which quantifies directional redistribution between structural dynamical scales rather than physical transport across nodes. Numerical simulations on modular and hierarchical networks reveal highly structured, intermittent spectral transfer episodes characterised by forward and inverse spectral cascades, directional reversals, and complex interaction geometries. Crucially, we demonstrate a clear separation between macroscopic coherence and microscopic spectral interactions, showing that highly organised, fluctuating internal redistribution dynamics persist even beneath nearly stationary and featureless global synchronisation states. This framework extends conventional synchronisation analysis and establishes a multiscale approach for interpreting network dynamics as an evolving process of spectral reorganisation.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Pulsar magnetospheres in dynamical Chern-Simons gravity: deathline conditions and polar-cap particle acceleration
Sherzod Sayfiyev, Bobomurat Ahmedov, Chengxun Yuan et al. (+3 more)
The role of surface
gravity in
neutron stars (NSs) is considerable in the radiation mechanisms of the surrounding
plasma magnetosphere near the
star surface, as they are highly magnetized, compact gravitating objects with compactness $M/R \simeq 0.2$. In this context, they serve as a celestial laboratory for testing
gravity theories that dominate the
stars' exteriors through
plasma magnetospheric radiation. In this paper, we examine how dynamical Chern-Simons (dCS)
gravity modifies
pulsar electrodynamics in the slow-rotation, weak-coupling regime; the leading-order correction affects only the off-diagonal metric component $g_{t\phi}$, while the diagonal components remain as in General Relativity (GR). We first solve the Maxwell equations in the dCS framework for the electromagnetic field components and obtain analytical solutions for the electric and
magnetic fields. We show that the
magnetic field components are the same as in GR, while the electric field components are modified in dCS. We then derive analytic expressions for the induced electric charge density, known as the Goldreich-Julian (GJ) charge density, which sources the induced electric field arising from the
magnetic field and the
star's rotation. In dCS, it is larger than in the GR case, whereas the accelerating electric field parallel to the
magnetic field lines is weaker. Next, we consider the deathline condition for switching off electron and positron radiation via inverse Compton scattering in the
star's polar cap zone and show that the line shifts upward in the $P-\dot{P}$ diagram, explaining the physics of shorter-lived
pulsars. Lastly, we study charged-particle acceleration in the polar cap region and show that electrons reach higher energies over shorter distances than in the GR case.
Read the full abstract ▾
All authors Sherzod Sayfiyev, Bobomurat Ahmedov, Chengxun Yuan, Javlon Rayimbaev, Bahodir Ahmedov, Asadbek Shermanov
Geophysics
Shape matters: DEM investigation of geometry-controlled mechanical response in irregular rock fragments under static and dynamic loading
Athena Bahramiyarahmadi and Rick Chalaturnyk
Mechanical characterization of subsurface rock formations typically requires standardized cylindrical core specimens, which are often unavailable from fractured or unconventional reservoir sequences. This study uses a Discrete Element Method (DEM) framework calibrated to Sulphur Mountain Formation siltstone to investigate how fragment geometry governs mechanical response in irregular rock particles, which are direct analogues of drill cuttings. Nineteen specimens (18 procedurally generated irregular geometries and one reference Brazilian disk), normalized to a 10 mm bounding sphere radius, were tested under quasi-static (Brazilian-type) and dynamic (Short Impact Load
Cell) loading modes. Four mechanical outputs of failure force (Ff), apparent strength ({\sigma}f), apparent stiffness (Ka), and stiffness (E) were regressed against seven retained shape descriptors. Results show that force-based quantities are strongly controlled by the surface-area-to-volume (SA/V) ratio under static loading (Adj. R2 = 0.69), while area-normalized quantities ({\sigma}f and E) are geometrically insensitive. Dynamic loading amplifies
geometric sensitivity for failure force and introduces an independent role for surface concavity depth. These findings establish a preliminary quantitative framework for interpreting mechanical measurements from irregular rock fragments when a standardized core is unavailable.
Read the full abstract ▾
Quantum Physics
Repairability of Inexact Solvers in Recursive State Estimation with Machine Learning
Yanjun Ji, Dennis Willsch, Orkun Şensebat et al. (+8 more)
Recursive state estimation often executes approximate numerical solutions inside a feedback loop, where highly accurate local steps do not guarantee better overall results. For a fixed linear Kalman model, we characterize when a correction within a prescribed subspace and norm budget can meet a local admissibility tolerance, and how the defects actually executed affect the finite-horizon covariance response. Centering each defect on the exact gain for the implemented covariance separates current solve error from inherited gain drift. Expanding the exact residual-drift identity reveals opposing quartic contributions beyond the quadratic response: innovation-covariance inflation enters positively, while local-gain reoptimization enters subtractively. Under matched initialization, an absolute sixth-order remainder bound, uniform over bounded defect sequences at fixed horizon, gives sufficient conditions for quadratic under- or overprediction. Machine learning proposes bounded corrections, while a learner-independent residual certificate and verified fallback govern execution of classical and
quantum candidates without changing the reference
estimator. In a power-grid tolerance study, learned correction lowers the minimum conjugate-gradient iteration count for deployment without fallback relative to uncorrected solves under the same residual certificate. Gains reconstructed from a variational
quantum linear solver and from an annealing-based binary encoding, with small-scale terminal measurements on superconducting hardware and sampling on a
quantum annealer, are executed through the same interface. By linking local repairability to nonlinear error propagation, the framework evaluates approximate solvers and learned corrections through independent certification and finite-horizon response, providing a practical basis for studying hybrid
quantum–classical computation.
Read the full abstract ▾
All authors Yanjun Ji, Dennis Willsch, Orkun Şensebat, Priyanka Arkalgud Ganeshamurthy, Zhi Pei, M. Sahnawaz Alam, Ivelina Stoyanova, Frank K. Wilhelm, Bo Zhao, Chao Wang, Kristel Michielsen
Physics Education
Exploring pedagogical content knowledge of physics teaching assistants using the Energy and Momentum Conceptual Survey
Liam Doyle, Alexandru Maries and Chandralekha Singh
This study examines the extent to which physics graduate teaching assistants (TAs) are aware of introductory physics student thinking and the types of challenges introductory students commonly have with energy and momentum concepts, which is important for implementing active learning methodologies and supporting diverse learners in physics courses. We present findings from a TA professional development course and discuss an approach to investigate TAs' pedagogical content knowledge, specifically their ability to recognize introductory student conceptual difficulties. We investigated 70 first-year graduate TAs' ability to identify common introductory physics student difficulties on the Energy and Momentum Conceptual Survey (EMCS). The TAs participated in a professional development course that emphasized reflection on introductory student thinking patterns to promote evidence-based pedagogical practices. TAs predicted the most common incorrect answers introductory students would select after lecture-based instruction, then compared their predictions with actual data from introductory students followed by a class discussion. Results reveal gaps between TAs' perceptions and introductory student thinking, with TAs performing poorly on many of the analyzed questions. For example, TAs consistently overestimated that introductory physics students would use novice-like thinking in many situations posed in EMCS problems, i.e., they expected introductory physics students to make more novice-like errors than they did. These findings have important implications for effective instructional design, e.g., physics TAs who misunderstand introductory physics student capabilities may inadvertently create barriers to learning by spending valuable class time on either over-scaffolding or under-challenging introductory physics learners and not spending time on pedagogical issues that are important to address.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Performance-portable GPU acceleration of the hybrid particle-in-cell code dHybridR
Bricker Ostler, Miha Cernetic and Damiano Caprioli
Hybrid particle-in-
cell simulations are widely used to study kinetic processes in collisionless astrophysical and space
plasmas, yet the high computational cost of large-scale three-dimensional runs has largely confined production studies to two dimensions or restricted domains. To address this challenge, we present a performance-portable GPU implementation of the hybrid particle-in-
cell code dHybridR. The implementation combines OpenMP target offloading with specialized SYCL kernels for the most computationally expensive operations, while preserving a unified CPU-GPU codebase that supports Intel, AMD, and NVIDIA GPUs. On the exascale supercomputers Aurora and Frontier, dHybridR achieves weak scaling efficiencies of $86\%$ to $97\%$ across 49,152 accelerators, and at 256 particles per
cell, its full-node GPU throughput is up to $32\times$ that of the vectorized CPU implementation at approximately $90\%$ less energy per particle-update. To our knowledge, no other hybrid particle-in-
cell code has reported GPU performance at this scale, leaving dHybridR uniquely positioned to exploit exascale systems. These advances substantially lower the computational barrier to large-scale three-dimensional hybrid-kinetic simulations of collisionless
plasmas.
Read the full abstract ▾
High Energy Physics (Theory)
Fermionic cosmic strings in dynamical Chern-Simons gravity
Stephon Alexander, Heliudson Bernardo and Shengyuan Zhang
We investigate topological defects produced by a
chiral phase transition in a fermionic ultraviolet completion of dynamical Chern-Simons (dCS)
gravity. The model contains a complex scalar field with a
chiral Yukawa coupling to
fermions. Below the
chiral symmetry breaking scale, integrating out the gapped bulk modes produces a gravitational Chern-Simons coupling which, we argue, modifies
cosmic string solutions from the phase transition. The resulting corrected string metric is supported by a generalization of the Callan-Harvey fermionic zero mode solution, in which the null current generated by these zero modes provides a mechanism for parity violation. In the weak-coupling and weak-
gravity regime, we derive the leading order-reduced dCS correction to this exterior metric. We also discuss the effective action description for generic string configurations in dCS
gravity. The gravitational Pontryagin term provides the anomaly inflow required to cancel the gravitational anomaly of the
chiral worldsheet theory.
Read the full abstract ▾
Solar and Stellar Astrophysics
A Search For Stellar-mass Black Holes Via Astrometric Microlensing II: 2012-2015 Keck Candidates
Mace J. Huston, Jessica R. Lu, Casey Y. Lam et al. (+55 more)
The Milky Way is expected to host $\sim$10$^8$
stellar-mass black holes with an uncertain binary fraction. The only proven method to detect isolated
stellar mass black holes is gravitational microlensing. Here we report the results of a microlensing search for black holes with photometry and astrometry. By combining 10 years of seeing-limited photometry from OGLE and MOA with diffraction-limited photometry and astrometry from adaptive optics imagers at the W.~M.~Keck Observatory, we constrain lens masses for OGLE-2012-BLG-0169, OGLE-2014-BLG-0613/MOA-2015-BLG-041, OGLE-2015-BLG-0029/MOA-2015-BLG-170, and OGLE-2015-BLG-0211. Of the four long-duration microlensing events monitored, we ruled out black hole lenses in 3 events, which likely have
stellar or white
dwarf lenses. OGLE-2015-BLG-0211 remains a black hole candidate with a poorly constrained lens mass with a 1$\sigma$ upper mass limit of 3.2$M_\odot$ and a 3$\sigma$ upper mass limit of 21.6$M_\odot$. This event suffered from poor observing conditions and significant astrometric reference frame uncertainties, but its analysis may benefit from additional astrometric data in the upcoming
Gaia Data Release 4. Of the six long-timescale ($t_E>100$ days) microlensing events from this work and previous studies, one black hole has been confirmed with a second not ruled out. We briefly examine
Galactic model simulations and find that our result agrees with current expectations. Ultimately, we need a larger sample of isolated black holes to constrain their formation processes. This will be possible in the coming years with Rubin and Roman, as well as improved astrometry from JWST and large, ground-based
telescopes equipped with adaptive optics.
Read the full abstract ▾
All authors Mace J. Huston, Jessica R. Lu, Casey Y. Lam, J. Nijaid Arredondo, Natasha S. Abrams, Shep Brooke, Sage H. Remulla, Eran Ofek, Michael S. Medford, Fatima Abdurrahman, Shrihan Agarwal, Edward Broadberry, Matthew Freeman, Matthew W. Hosek Jr., Siyao Jia, Sean K. Terry, The OGLE Collaboration: Andrzej Udalski, Przemek Mroz, Radoslaw Poleski, Jan Skowron, Michal K. Szymanski, Igor Soszynski, Pawel Pietrukowicz, Szymon Kozlowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Mariusz Gromadzki, Mateusz J. Mroz, Michal Malkowski, The MOA Collaboration: Fumio Abe, David P. Bennett, Aparna Bhattacharya, Ian A. Bond, Kotaro Daimon, Ryusei Hamada, Yuki Hirao, Shuma Makida, Stela Ishitani Silva, Shota Miyazaki, Yasushi Muraki, Tutumi Nagai, Kansuke Nunota, Ryo Ogawa, Ryunosuke Oishi, Hideaki Ose, Greg Olmschenk, Clement Ranc, Nicholas J. Rattenbury, Yuki K. Satoh, Takahiro Sumi, Daisuke Suzuki, Takuto Tamaoki, Chihiro Ueda, Paul J. Tristram, Aikaterini Vandorou, Hibiki Yama
Instrumentation and Methods for Astrophysics · Cross-listed from stat.AP
Multivariate Continuous-Time Autoregressive Moving Average Processes for Astronomical Multiband Time Series
Izak Schmidlkofer, Zhirui Hu, Lishan Shi et al. (+2 more)
Large-scale astronomical surveys provide unprecedented volumes of multivariate time-series observations obtained through multiple optical filters. We develop a structured multivariate continuous-time autoregressive moving average (MCARMA) framework for multi-band time series with irregular sampling, heteroscedastic measurement errors, and partially observed bands. The framework allows band-specific
stochastic dynamics while modeling cross-band dependence through correlated Brownian driving processes, with state-space and spectral representations enabling likelihood-based inference and interpretation of the fitted
stochastic dynamics. We develop a two-stage estimation procedure in which a numerically stabilized preliminary fit initializes subsequent maximum likelihood estimation. Simulations show that higher-order
stochastic structure can be recovered when its characteristic features are adequately resolved, but can become weakly identifiable because of limited temporal resolution or near pole–zero cancellation. Joint multivariate estimation improves parameter recovery in 23 of 27 settings and spectral recovery in 26 of 27 settings relative to separate single-band fits. Three Sloan Digital Sky Survey Stripe 82
quasars, respectively favoring MCARMA(1,0), MCARMA(2,0), and MCARMA(2,1), illustrate how joint multiband modeling uses cross-band dependence to inform marginal dynamics and can yield different model-order and spectral inference. The methodology is implemented in the Python package mcarma.
Read the full abstract ▾
All authors Izak Schmidlkofer, Zhirui Hu, Lishan Shi, Weixiang Yu, Hyungsuk Tak
Strongly Correlated Electrons
Intrinsic anomalous Hall effect in the surface conduction regime of non-magnetic narrow-gap insulator FeSi
Yong-Cheng Pan, Hwai-Chi Lin, Li-Han Wang et al. (+6 more)
The realization of an intrinsic anomalous
Hall effect (AHE) in the absence of bulk magnetism is a rare phenomenon, requiring a spontaneous breaking of the time-reversal
symmetry within the boundary states without a thermodynamic phase transition. Here, we report a robust, zero-field-hysteretic intrinsic AHE confined to the low-temperature surface-conduction regime of the prototypical narrow-gap
insulator FeSi. By systematically investigating single
crystals grown via Czochralski and chemical vapor transport methods with controlled thicknesses and surface preparations, we demonstrate that low-temperature electrical conductivity correlates with surface roughness and anti-correlates with sample thickness, confirming the emergence of surface conducting states (CSS) below $T_{\rm CSS} \simeq 55-75\text{ K}$. Meanwhile, a robust, field-hysteretic and temperature-independent anomalous
Hall conductivity is found below $T_{\rm AHE}\simeq45-70\text{ K}$, implying the presence of
magnetic order in the surface conduction regime. Bulk
magnetic susceptibility and specific-heat measurements reveal no thermodynamic phase transitions, verifying that the sample interior remains a non-
magnetic insulator. Analyses of conductivity scaling and effective three-dimensional conductivity reveal the intrinsic nature of this surface-driven AHE, evidencing the presence of an emergent
magnetic order within the metallic surface of a non-
magnetic bulk
insulator. These findings establish FeSi as a compelling platform to investigate the interplay between strong electron correlations and anomalous
Hall transport.
Read the full abstract ▾
All authors Yong-Cheng Pan, Hwai-Chi Lin, Li-Han Wang, Chia-Nung Kuo, Han-Shiuan Lin, Che-Ning Yeh, Chin-Shan Lue, Anne de Visser, Yu-Te Hsu
High Energy Physics (Phenomenology)
Inelastic dark matter mediated by natural dark photon
Jie Tang and Pei-Hong Gu
At loop level, a dark $U(1)_X^{}$ gauge field for dark
photon can naturally acquire a tiny kinetic mixing with the standard model $U(1)_Y^{}$ gauge field for hypercharge after a $Z_2^{}$ discrete
symmetry is spontaneously broken for generating a small mass difference between two vector-like
fermions carrying the same $U(1)_Y^{}$ charge and the opposite $U(1)_X^{}$ charges of equal magnitude. To avoid an unacceptable relic density with electric charge, these vector-like
fermions can decay into the standard model charged
leptons with a TeV-scale complex dark scalar. The real and imaginary parts of this dark scalar can elegantly obtain a mass split below the MeV scale after a dark
Higgs scalar develops its
vacuum expectation value for generating a dark
photon mass of the GeV order. Therefore, the dark
photon can mediate an exothermic inelastic scattering of dark matter off
nucleus to naturally explain the recently reported event in the LUX-ZEPLIN experiment and substantially relax the stringent constraints from the IceCube
neutrino searches.
Read the full abstract ▾
Nuclear Theory
Strange Quark Stars and Spontaneous Scalarization
Mina Mehraeen Nazdik and Zeinab Rezaei
Strange
quark matter, as one of the most extreme dense states in astrophysics, can be explored through relativistic compact objects. Hypothetical relativistic
stars composed of dense strange
quark matter are characterized by the equation of state of that matter. The spontaneous scalarization of strange
quark stars is influenced by the equation of state of strange
quark matter. Here, we investigate how the equation of state of strange
quark matter influences the spontaneous scalarization of these
stars. Considering Normal, color-
flavor-locked (CFL), and CFLm
quark matter in the bag models and applying the scalar-tensor
gravity, we calculate the structure of scalarized strange
quark stars. We investigate how the effective bag constant, perturbative QCD parameter, CFL pairing gap, and strange
quark mass control the mass-radius relation, the central scalar field, the scalarization thresholds, and the scalar charge. Our results demonstrate that strange
quark stars in scalar-tensor
gravity are viable, testable objects, and they establish a complete framework for constraining both the gravitational theory and the properties of cold
quark matter with current and future multimessenger observations.
Read the full abstract ▾
Astrophysics of Galaxies
Interstellar extinction of classical Cepheids from neighboring stars I. Methodology and application to 16 Galactic Cepheids
Wilma Kiviaho, Pierre Kervella, Mika Juvela et al. (+21 more)
Galactic Cepheid variable
stars are fundamental calibrators of the
cosmic distance scale through their Period-Luminosity (PL) relation. The high-precision parallaxes expected from
Gaia Data Release 4 (DR4) will enable a calibration of the Milky Way PL relation with unprecedented precision. This will place stringent requirements on interstellar extinction corrections, which remain a dominant source of uncertainty. We strive to derive highly accurate extinction values for
Galactic Cepheids. We present an innovative methodology relying on the analysis of neighboring field
stars and apply it to a pilot sample of 16 Cepheids. We identify physically near field
stars using
Gaia DR3 astrometry. For these
stars, we determine atmospheric parameters from medium- to high-resolution VLT/FLAMES spectroscopy. Fixing these parameters, we derive individual extinctions by fitting spectral energy distributions constructed from
Gaia XP spectra and infrared photometry. We then reconstruct the three-dimensional distribution of extinction and interpolate extinction to the Cepheid position. We report extinction Av, total-to-selective extinction ratio Rv, and color excess E(B-V) for all 16 Cepheids. Our method achieves a mean precision of approximately 5%, improving upon typical literature values, with no significant systematic offset detected. We demonstrate that using field
stars bypasses uncertainties associated with Cepheid variability and can provide robust extinction estimates for
Galactic Cepheids.
Read the full abstract ▾
All authors Wilma Kiviaho, Pierre Kervella, Mika Juvela, Alexandre Gallenne, Nicolas Nardetto, Carine Babusiaux, Rosine Lallement, Vincent Hocdé, Garance Bras, Nancy Remage Evans, Antoine Mérand, Grzegorz Pietrzyński, Gergely Hajdu, Henryka Netzel, Ricardo Salinas, Bogumił Pilecki, Cezary Gałan, Frédéric Arenou, Manon Bailleul, Katia Sivkova, Daniela González, Louise Breuval, Rajeev Singh Rathour, Brankica Apostolova
Optics
Label-Efficient Generative Inverse Design and Design-Rule Discovery in Freeform Topological Photonics
Yuhan Zhang, Xin Xie, Bowen Song et al. (+3 more)
Topological photonic
crystals support robust, disorder-resilient light transport protected by their band-structure
topology, yet their design remains confined to a small set of
symmetry-defined templates. The surrounding freeform design space, where optimal performance and new functionality may reside, is difficult to access because of its high dimensionality and costly full-wave simulation needed for evaluating each candidate. % Here we report generative inverse design of freeform valley photonic
crystals. A label-free
diffusion prior learns the distribution of three-fold rotationally symmetric geometries from 7,689 unlabeled designs that cost 0.15~s each to produce, while a convolutional surrogate is trained on 1,666 full-wave band-gap simulations costing 4.28~min each, exploiting a 1,700-fold cost asymmetry. Across nine target band gaps up to $225~$meV, we generate and verify by full-wave simulation 270 valley photonic
crystal designs, reaching a mean absolute error of $1.4$–$6.7$~meV within the labeled range and retaining below $5.1\%$ fractional error at targets $25\%$ beyond its upper bound, while a label-conditioned
diffusion model trained on the same label data performs substantially worse. Beyond inverse design, the trained model functions as an instrument for discovering structure–property relations. At a target band gap where the labeled set contains only five designs, it generates hundreds, resolving
geometric trends that are statistically inaccessible in the training data and yielding interpretable rules for large-gap valley photonic
crystals. Our results establish surrogate-guided
diffusion as a label-efficient route to freeform topological-photonic design, and as a means of extracting design principles where physical intuition and simulation labels are both scarce.
Read the full abstract ▾
All authors Yuhan Zhang, Xin Xie, Bowen Song, Lixuan Chen, Liyue Shen, Hui Deng