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Tuesday 1 September

Materials Science

Accelerating dynamic simulations of photoexcited materials and their evolution by electron-informed machine learning

Nonadiabatic coupled electron-nuclear dynamics upon electronic excitation underpin the microscopic mechanism and rational modulation of diverse photoinduced functional phenomena in materials, yet their direct first-principles simulations remain computationally demanding. Here we develop a framework for nonadiabatic excited-state machine-learning molecular dynamics (EMLMD) simulations, where the nonequilibrium electronic information upon photoexcitation such as electron temperature is rigorously calibrated from high-precision real-time time-dependent density functional theory (rt-TDDFT) benchmark simulations, enabling accurate reconstruction of excited-state potential energy surfaces (PES). This framework natively incorporates the excited-state electron-phonon couplings and intrinsically captures photoinduced phonon anharmonicity, both of which are missing in standard machine learning molecular dynamics, thus delivering first-principles-level accuracy for excited-state atomic evolutions. Large-scale EMLMD simulations resolve time- and momentum-resolved phonon dynamics in photoexcited materials, directly uncovering the competition between photogenerated coherent phonons and thermal phonons during photoinduced phase transition of bismuth. It also simultaneously resolves elusive atomic-scale microscopic dynamics and global structural rearrangement for selenium photoamorphization. Balancing high accuracy and efficiency, EMLMD offers a versatile paradigm to tackle key challenges in the study of complex excited-state molecular dynamics.
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All authors Yunzhe Jia, Fankai Xie, Yunfei Bai, Miao Liu, Cui Zhang, Sheng Meng

Fluid Dynamics

Jet creation and wave energy dissipation by a submerged elastic plate

Experiments on a flexible plate horizontally submerged in a wave tank are reported in this paper. The plate is held at a fixed depth at its upstream end, while its downstream end is free to move. The wave field is measured using a synthetic Schlieren technique, giving access to an estimate of the fractions of the incoming wave energy that are transmitted and reflected after encountering the region where the plate is submerged. Part of the incoming wave energy is shown to be dissipated by the plate. Flow field measurements in a vertical plane parallel to the wave propagation are performed to examine the wave-plate interaction. A jet-like flow is produced at the free end of the plate, with strong vortex activity similar to that produced by a flapping fin. The kinetic energy present in this jet-like flow is computed from the velocity field measurements, and the external dissipation produced by jet creation is estimated. Results highlight the efficiency of flexible plates in reflecting and attenuating waves. This study also showcases a change in jet direction, in particular the observation of a jet going upward toward the free surface for certain frequencies. Such a configuration, could be of great interest for wave energy conversion applications, while preventing harmful phenomena such as seabed erosion.
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All authors Diane Komaroff, Gatien Polly, Alexis Mérigaud, Benjamin Thiria, Ramiro Godoy-Diana

High Energy Physics (Phenomenology)

Gravitational Waves from Reheating beyond Instantaneous Thermalization

We study gravitational-wave production during perturbative reheating without assuming instantaneous thermalization of the inflaton decay products. The injected energetic particles thermalize through an in-medium cascade of nearly collinear splittings subject to the Landau-Pomeranchuk-Migdal effect and are ultimately isotropized by elastic scatterings near the thermal scale. The non-thermal hard population present before complete thermalization produces an additional gravitational-wave component through hard-soft scatterings, with $\Omega_{\mathrm{GW}}\propto f^{1/2}$ below the injection-scale turnover. The same isotropization erases the directional information underlying the vacuum $1/k$ bremsstrahlung soft pole, changing the deep-infrared spectrum from $\Omega_{\mathrm{GW}}\propto f$ to $\Omega_{\mathrm{GW}}\propto f^3$.
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Physics Education

What do student responses to the car-truck problems tell us? An investigation into two Force Concept Inventory questions

Concept inventories are widely used in Physics Education Research to uncover student misconceptions and measure the effectiveness of instruction. Two questions in the widely used multiple-choice Force Concept Inventory concern a car that is pushing a truck, as the car is accelerating and then when a steady speed has been reached. We investigate the premise that correct answering of these questions is because of good conceptual understanding of Newton's Third Law, by analyzing responses to a modified inventory that randomly offers students multiple-choice or free-text versions of the questions and follows these with questions in which students select the physical principle(s) they used. The results from 674 attempts from students at six universities show a similar pattern of results for multiple-choice and free-text versions, also comparable with Force Concept Inventory results from one of the universities in the preceding five years, but with marked differences relative to early published Force Concept Inventory data. Free-text responses and the law-selection sub-questions can reveal more about conceptual understanding than can be seen in multiple-choice responses alone. For the accelerating system (Question 15), correct responses are usually attributed to Newton's Third Law and incorrect responses are usually attributed to Newton's Second Law. When speed is constant (Question 16), around 90% of responses are correct, but a significant number of these are attributed to Newton's First Law or the Superposition Principle rather than Newton's Third Law, especially pre-instruction. We conclude that students are confusing balanced forces on a single object moving at constant speed with the correct equal-and-opposite interaction pair between two objects, and correct responses to Question 16 may be concealing an underlying misconception.
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All authors Ashutosh Kumar Pathak, Mark A.J. Parker, Ross K. Galloway, Andrew J. A. James, Sally E. Jordan, Jonathan Nylk

Superconductivity

Superconducting diode effect from field-induced $s+if$ pairing in Ising superconductors

The in-plane critical field of Ising superconductors exceeds the Pauli limit by an order of magnitude because the Ising spin-orbit coupling locks the electron spins out of the basal plane. The same locking converts an in-plane Zeeman field into a source of equal-spin triplet Cooper pairs, so that the field-driven condensate acquires an $s+if$ character. We show that this conversion channel also generates Lifshitz invariants, the odd-in-momentum terms of the Ginzburg-Landau expansion responsible for the superconducting diode effect. When the basal mirror symmetry of the monolayer is lifted by a substrate or a gate, the field-induced triplets couple linearly to the Cooper-pair momentum, and an intrinsic diode response develops whose strength is set by the ratio of the Zeeman and spin-orbit energies rather than by the small ratio of the spin-orbit and Fermi energies familiar from parity-mixing mechanisms. We construct the symmetry-constrained two-component Ginzburg-Landau theory of the coupled singlet and triplet order parameters and derive all of its coefficients from the microscopic model of an Ising superconductor; the complete functional, including all gradient and quartic terms, is generated by a single pair-breaking function of temperature, field, and Cooper-pair momentum. An attractive triplet channel reshapes the diode response: at weak fields it suppresses the efficiency through destructive interference between the direct and the collective-mode conversion paths, while at strong fields it extends the diode regime well beyond the singlet-only critical field, with the maximal efficiency reached along the triplet-enhanced phase boundary. The diode effect thereby serves as a transport probe of a hidden triplet pairing channel and of the field-induced $s+if$ state.
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High Energy Physics (Phenomenology)

Inelastic Dark Matter Signature at High Recoil Energy in LUX-ZEPLIN and CRESST

The LUX–ZEPLIN Collaboration recently reported one event at $E_{\mathrm{nr}}=248\pm23~\mathrm{keV}$ with an exposure of $2.84~\mathrm{tonne\cdot yr}$. In this Letter, we interpret this feature using endothermic dark matter (DM). We consider both direct scattering of the surviving ground-state halo component and the contribution of excited states produced by terrestrial upscattering. Our calculations show that explaining the high-energy event requires $m_\chi\gtrsim500~\mathrm{GeV}$ and a mass splitting of $\mathcal{O}(300)~\mathrm{keV}$, for which the production of excited states inside the Earth is kinematically forbidden. For $\bar{\sigma}_n=10^{-37}~\mathrm{cm^2}$, an illustrative two-bin likelihood analysis yields a representative best-fit point at $(m_\chi,\delta)\simeq(1.105~\mathrm{TeV},350~\mathrm{keV})$. The preferred parameter region may be tested by the planned CRESST upgrade.
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Plasma Physics

A Magnetothermodynamic Theory of Energy Transport In Collisionless Plasmas

Presented here is an exploratory conceptual framework with the aim of describing electromagnetic and thermal energy transport and transfer in collisionless plasmas in a coherent way, starting from an arrow-of-time perspective. That is, arguments about the transport of energy are fundamentally based on the idea that systems tend to fill the phase space available to them. First, we describe electric fields, magnetic fields, and plasma particles as interacting subsystems that are thermodynamically linked in specific ways. Second, we discuss the importance of the stochastic electric field in the transport of plasma particles down energy density gradients until the energy flux contributions from so-called electrothermodynamic (ETD) interactions become sufficiently uniform. Third, the logic of ETD transport is extended to a magnetized system invoking 2 types of magnetothermodyamic (MTD) transport: 1) transport of electromagnetic energy through stochastic Poynting flux and 2) plasma energy transport through stochastic drift energy fluxes associated with local ExB drift motion. The magnitudes of the ETD and MTD mechanisms are tied to local characteristic scales of the electric field fluctuations and critical scales are derived beyond which ETD mechanisms dominate MTD mechanisms. Finally, we discuss the interplay between electrothermodynamic and magnetothermodynamic equilibria (ETE and MTE), dynamics in the small critical scale (MTD) limit, and the potential relevance of this type of description to the problem of reconnection onset and scale coupling.
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Chemical Physics

Reference-Density Hartree Screening for Gausslet Hamiltonians

Gausslets are among the few electronic-structure bases that permit the four-index electron–electron interaction to be replaced by an accurate two-index integral diagonal approximation (IDA). Near a many-electron nucleus, however, the nuclear attraction and core-electron Hartree field are individually large and substantially cancel. Treating the first as a full finite-basis matrix while treating the second with IDA leaves an avoidable imbalance. We introduce reference-density Hartree screening: the Hartree field of a chosen reference density is represented accurately, and IDA is applied only to density fluctuations about it. Tests on He, Ne, atomic F, F$_2$, and Cr$_2$ show large reductions in direct Hartree errors, including transfer of fitted neutral-atom fields to molecules. For Cr$_2$, atomic-core screening prevents the spurious HF collapse found with the unscreened $q=5$ and $q=7$ Hamiltonians, whereas finite-reference matching without screening does not. Screening leaves exchange and residual correlation unchanged. We therefore also introduce a low-rank one-particle correction that uses an accurate conventional Gaussian-basis Hartree–Fock calculation to match either occupied-space exchange information or the complete occupied Fock vectors. In F$_2$ and Cr$_2$, $X_{\rm HF}$ reproduces the finite-reference energy and occupied Fock vectors to numerical precision and the selected states return after orbital perturbations. For Cr$_2$, the corrected $q=5$ basis uses one quarter as many functions as the $q=7$ control while retaining sub-mHa mean-field accuracy. Screening provides the physical improvement to the direct field; the state-specific correction then restores the remaining accuracy of the Gaussian-basis mean-field reference.
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High Energy Physics (Theory)

Lagrangian varieties from $q$-matrix models

We consider three specific $q$-deformed matrix models (the Chern-Simons, $q$-Laguerre, and $q$-Gaussian matrix models) which can be solved explicitly using the property of superintegrability. We show that one- and two-point functions of inverse characteristic polynomials can be interpreted as quantizations of Lagrangian subvarieties in $(\mathbb{C}^*)^2$ and $(\mathbb{C}^*)^4$, respectively. While such a geometric picture is expected for the Chern-Simons matrix model, our results for the $q$-Laguerre and $q$-Gaussian models are new and exhibit additional features. In particular, specific anti-symplectic birational involutions play an essential role in the construction. This reformulation provides a geometric framework for analyzing the semiclassical, large-$N$ expansion of matrix-model correlators. This picture is suggestive of the geometry underlying open topological strings, although the two constructions are not identical and the precise relation between them remains to be understood.
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Instrumentation and Methods for Astrophysics

Project management of the Canadian Hydrogen Observatory and Radio-transient Detector

The Canadian Hydrogen Observatory and Radio-transient Detector (CHORD) is a new drift-scan radio interferometer operating from 300-1500 MHz, optimized for 21cm intensity mapping, 21cm galaxy detection, pulsars, and transient detection and localization. The full instrument will feature a core array of 512 six-meter dishes, plus two 64-dish outriggers at several thousand kilometer baselines. The project is nearing completion of the first 64-dish sub array, which will enable commissioning activities to begin in parallel with the remaining construction. In this presentation, we discuss the project management framework that has enabled us to navigate the logistical challenges of a fixed-budget, fixed-timeline research infrastructure project through a period of significant global economic and technological volatility.
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All authors Dallas Wulf, Matt Dobbs, Brian Hoff, Michael Rupen, Kendrick Smith, Keith Vanderlinde

Quantum Physics · Cross-listed from cs.FL

Behavioral Memory under Symmetry in One-Way Quantum Automata

Under compact symmetry, observable behavior reduces to an invariant operator algebra, but its dimension is not yet classical memory: some coordinates are dynamically frozen, some invisible to threshold tests, and some already classical. We develop an operator-algebraic theory that separates these effects through three filters. For one automaton, behavior is the Hilbert–Schmidt pairing between prefix-reachable states and suffix-observable effects, whose rank equals the real Hankel rank without controllability or observability assumptions. Maximizing this invariant over a symmetry-constrained dynamical class gives a structural capacity controlled by the symmetry commutant: its center stores isotypic populations frozen by reversible dynamics, its traceless multiplicity blocks carry movable noncommutative coordinates, dissipation removes the unary spectral loss inside those blocks, and covariant mobility releases relative populations subject to component conservation. Operational realization then determines which surviving coordinates force probabilistic states. For a fixed nontrivial invariant readout, full mobility gives an exact dichotomy in worst-case state cost: a commutative invariant algebra costs exactly its dimension, whereas a noncommutative multiplicity block raises the unrestricted cost by exactly one state. Thus noncommutativity has a one-state worst-case classical price. The known four-letter quadratic-plus-one law at trivial symmetry is the fully mobile endpoint of this principle. Schur–Weyl duality further shows that different preserved symmetries on the same tensor-power Hilbert space can change the worst memory scale from polynomial to exponential, while fixed-weight modules give an exact Catalan law at half filling, with structural capacity equal to the Catalan count minus its central-sector correction.
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Quantum Physics

Verifiable quantum advantage in extremely low depth

We give a sampling problem that is solvable by shallow quantum circuits, hard for polynomial-time classical algorithms under lattice-based assumptions, and efficiently verifiable by a classical computer. The quantum sampler admits two implementations: one uses log-logarithmic-depth quantum circuits with one- and two-qubit gates, i.e., $\mathsf{QNC}^0[\log\log]$ circuits, while the other uses constant-depth quantum circuits with unbounded fan-in gates, i.e., $\mathsf{QAC}^0$ circuits. Our construction can be seen as compiling the Learning with Errors (LWE)-based single-round proof of quantumness of Arabadjieva et al. (2025) to very low depth. The price paid for this compilation is the reliance on less standard, though well-motivated, assumptions: in addition to the lattice knowledge assumption used by Arabadjieva et al. (2025), we require a strengthened variant of the adaptive-hardcore-bit property of LWE, for which we provide supporting evidence. Unlike previous low-depth proofs of quantumness, the quantum computation here requires no mid-circuit measurements or feed-forward: it consists only of running a shallow circuit and sampling from its output distribution. This shows that shallow quantum circuits have sufficient structure to solve certain classically hard tasks whose solutions can be verified efficiently.
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Materials Science

Polar nanoregions and reentrant-like ferroelectric behavior in SrTiO$_3$

Recent real-space imaging in quantum paraelectric SrTiO$_3$ [Nature 656, 54 (2026)] reveals that local polar textures do not continuously grow upon cooling, but reach a maximum intensity at intermediate temperatures around 60-65 K and weaken again toward the quantum paraelectric ground state. Such a reentrant-like weakening of local polar textures challenges the conventional paradigm in which ordering tendencies generally continue to strengthen as temperature decreases. Here we employ a self-consistent phase-field theory showing that this anomalous behavior naturally arises from the coupling between intrinsic polar and antiferrodistortiv (AFD) fluctuations. We demonstrate that the flexoelectric-like coupling strongly hybridizes the polar and AFD modes. As the uncoupled polar and AFD modes cross near 52 K, their hybridization is maximized, driving the lower hybridized branch to develop a minimum on a finite-wave-vector shell. This finite-$q$ softening triggers a Brazovskii-type instability, strongly enhancing polarization correlations and producing nanoscale polar textures. Away from the crossing temperature, the two modes become increasingly detuned, weakening their hybridization and the associated finite-$q$ softening. These results reaveal the origin of the formation of polar nanoregions in SrTiO$_3$, naturally explaining the unexpected confinement to an intermediate-temperature window and providing a mechanism beyond the quantum-fluctuation-based interpretation suggested by experiment. Furthermore, we predict an unconventional reentrant-like sequence in weakly strained SrTiO$_3$, evolving from ferroelectric to paraelectric, polar-nanoregion, and eventually paraelectric regimes upon heating from zero temperature.
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Fluid Dynamics

Macroscopic simulations of thin film wetting/dewetting using a precursor film model

Numerical simulation of dynamic wetting processes remains challenging due to the multiscale feature of the moving contact line. This paper presents a finite element method for two- or three-dimensional dynamic wetting problems within the framework of the lubrication equation and the precursor film model. By reconstructing the disjoining pressure formulation, a mesoscopic precursor film model is implemented to enable a relatively thick precursor film to reproduce the intermediate-region interfacial behavior of a physically thin precursor film. The proposed model reduces the requirement for excessive spatial resolution near the contact line, thereby significantly reducing the computational cost while preserving the macroscopic flow dynamics. This method does not incorporate any moving boundary and easily handles topological changes. Its capability and accuracy are validated through various simulations, including the spreading, retraction, sliding, and coalescence of drops, as well as the breakup of liquid ridges. Numerical results (with the mesoscopic precursor film model adopted) show good agreement with the available exact solutions and asymptotic theories.
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All authors Xi-Hu Wu, Zhuo Long, Xue-Li Wang, Peng Gao

Mathematical Physics

$A_1$ - Coulomb branches over finite fields and Selberg Character sums

Motivated by mirror symmetry, we study exponential sums over the $\mathbb{F}_q$-points of the $A_1$ Coulomb branch. We show that their fiberwise structure is governed by polynomial Gauss sums, providing a geometric realization of Selberg character sums studied by Evans. Using Evans's evaluation, we obtain explicit formulas for the Coulomb-branch exponential sums as products of classical Gauss sums.
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Mathematical Physics · Cross-listed from math.AP

Bose–Einstein Condensation without an Initial Low-Energy Concentration Assumption

We prove that semi-strong convergence to a Bose–Einstein equilibrium below the critical temperature implies finite-time Bose–Einstein condensation (BEC) for conservative isotropic measure solutions of the spatially homogeneous quantum Boltzmann equation with low-momentum scattering degeneracy exponent $0\leq\eta<1$. For every admissible initial measure with $\overline T/\overline T_c<1$, there exists a conservative solution that has a positive zero-energy atom after a finite time without any assumption of initial concentration near zero energy. We also show that it persists and converges to the equilibrium condensate mass, while the full solution converges strongly. The proof introduces a method to obtain condensation from relaxation estimate to Bose–Einstein equilibrium. The relaxation estimate first gives a fixed amount of mass below a small energy level. We then use collision estimates at smaller and smaller energy scales and add their effects in a weighted sum functional with a fixed upper bound. If no atom forms at zero energy, enough mass remains in the positive-energy shells to force this sum to exceed its upper bound in finite time, which leads to condensation in finite time.
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Chaotic Dynamics

Spatiotemporal Chaos with Extended Spatial Interactions

The chaotic dynamics of a large one-dimensional lattice of nonlinear maps with a spatial coupling of increasing extent is explored using the covariant Lyapunov vectors (CLVs). A theoretical approach is developed that predicts the spectral variation of the CLVs and the spectrum of Lyapunov exponents. The theoretical approach is independent of the details of the mapping function and requires only a description of the lattice coupling. The general structure of the spatial power spectrum of the CLVs is determined using only the eigenvectors of the coupling matrix. This yields a decomposition of the CLVs into two regimes. The first regime, corresponding to the largest Lyapunov exponents, contains highly entangled CLVs with significant contributions from large scale spatial structures and aligns with the sorted eigenvectors, which occur in pairs with wavenumbers that increase linearly with their index. The second regime contains significant mixing of length scales with increasing index. The index separating these two regimes is approximately equal to the fractal dimension of the dynamics.
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High Energy Astrophysical Phenomena

Extreme AGN Variability in WISE: Powerful Flares and Candidate Tidal Disruption Events in AGN

We present first results from a systematic study of extreme mid-infrared variability of active galaxies across the $>10$-year baseline of the Wide-field Infrared Survey Explorer (WISE) mission. WISE, which observed the full sky with a six-month cadence, is sensitive to transient events in both unobscured and obscured galaxies. This paper focuses on extreme flares in active galactic nuclei (AGNs). Previous studies identified flares such as tidal disruption events (TDEs) in inactive galaxies, typically from optical or X-ray surveys. However, flares are also expected in AGN and optical/X-ray searches are insensitive to events in dust-enshrouded AGN. In this pilot study, we present flares in two AGN identified from extreme mid-infrared color variability. One flare was also detected at optical wavelengths. While both events showed broadened H$\alpha$ emission several years after the flare peak, more recent spectroscopy reveals continued broadened emission only from the source with the optical flare. After considering several potential physical causes of the flares, including supernovae and micro-lensing, we suggest both events are TDEs in AGN. Intriguingly, the optical flare decays much faster than the expected $t^{-5/3}$ fallback rate expected for TDEs in quiescent galaxies, suggesting either a partial disruption or the tidal disruption of a star by an intermediate mass black hole embedded in the accretion disk of an AGN. This work demonstrates the power of WISE to identify the full census of TDEs, including events in dust-obscured AGN. Mid-infrared data probes the nature of the event and provides a bolometric measure of the flare energetics.
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All authors Satya Teja Anuraag Upadhyayula, Daniel Stern, Kishalay De, Christos Panagiotou, Matthew J. Graham, K. E. Saavik Ford, Barry McKernan, Murray Brightman, J. A. Acevedo Barroso, Daniel H. McIntosh

Quantum Physics

Exact Virtual Channel Programming with Vanishing Excess Overhead

A finite-dimensional physical processor cannot exactly program a continuous family of distinct unitary channels. We show that this obstruction becomes quantitative when the target channel is stored in a normalized Choi state and its output observables are reconstructed by sampling physical channels and classically post-processing their measurement outcomes. For arbitrary $d$-dimensional channels, we construct a target-independent exact reconstruction protocol and prove the optimal one-copy sampling overhead, which grows quadratically with system dimension. We further prove the sharp fixed-$d$ law that the excess overhead vanishes inversely with the number of identical Choi programs. The upper bound combines deterministic port-based teleportation with a quasi-decomposition that corrects its depolarizing distortion. The converse maps any low-overhead reconstruction protocol to a physical learner of unknown unitaries and uses local quantum estimation to recover the same leading coefficient. These results recast the universal no-programming obstruction as a quantitative trade-off between quantum program memory and classical sampling, with a leading cost that reflects the locally learnable unitary degrees of freedom.
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All authors Mingrui Jing, Mengbo Guo, Hongshun Yao, Xin Wang

High Energy Physics (Phenomenology)

Probing jet medium interaction with generalized projected energy correlators

We study medium modifications to generalized projected energy correlators, referred to as $\nu$-correlators, measured on jets in heavy-ion collisions. While the vacuum distributions of these correlators exhibit a characteristic $1/\nu$ enhancement, we show that in a dense medium this behavior is regulated within both the BDMPS-Z and semi-classical approximations as $\nu \to 0$. As a result, contributions from medium-induced emissions become parametrically suppressed relative to the vacuum baseline. We observe a similar trend in the simulated events generated with JEWEL. We find that while the large angle enhancement is qualitatively similar across different values of $\nu$, the small angle distribution changes drastically between $\nu<1$ and $\nu>1$. This indicates that small angle modifications, primarily driven by jet energy loss, are imprinted differently across $\nu$-correlators. In particular, for $\nu<1$ the small angle enhancement is less prominent which suggests that these correlators may provide improved sensitivity to medium modifications in the large angle region.
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Plasma Physics

The role of different nonlinearities and potential vorticity conservation in two-dimensional fluid ITG models

The nature of turbulent energy cascade of simple two-dimensional fluid models of ion temperature gradient driven turbulence is studied in detail. Notably, it is observed that a minimal two-field model of toroidal ITG, behaves qualitatively differently with or without the diamagnetic nonlinearity. In its absence, the zonal flows always dominate and the system never reaches a high-transport state. In contrast, when this term is included, zonal flows dominate only near marginality, while away from it, an inverse cascade with high levels of transport is observed, requiring large-scale dissipation (hypoviscosity) to saturate and hyperviscosity to regularize small scale instability associated with this nonlinear term. However introducing such a term, together with the existence of the curvature term, breaks potential vorticity conservation, which is one of the key symmetries of drift-wave turbulence. This can be remedied by considering a more complete model that retains higher-order terms in the pressure equation. This form of the model, with four nonlinearities, conserves potential vorticity and behaves similarly to the original model, requiring hyperviscosity to saturate since the added nonlinearity generates small scale instability also for the pressure equation. To characterize the roles of potential vorticity conservation and higher-order terms in the pressure equation, the behavior of both the standard ITG system, and the potential vorticity conserving system, is studied by analyzing their spectra, turbulent cascades, and sensitivity to viscosity. Finally, the direction of turbulent cascade due to the different nonlinearities (i.e. the diamagnetic nonlinearity in particular) is investigated by examining their contributions to the spectral energy transfer and by considering the triadic instability assumption for each of these nonlinearities separately.
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Cosmology and Nongalactic Astrophysics

Energy deposited by black holes in the hot X-ray gas of elliptical galaxies, groups and clusters

Galaxy groups show entropy excesses $\Delta S$ with respect to theoretical expectations from models and simulations with purely gravitational heating. We determine the heat $Q_{\rm heat}\simeq T\Delta S$ deposited by non-gravitational sources into the hot gas of elliptical galaxies, groups and clusters, and to compare it with the energy output of their central black holes (BHs). We adopt a simple model for the hot gas with only one free parameter: the core entropy. We calibrate the core entropy on the observed relation between X-ray luminosity and halo mass, and we use it to determine the entropy $S$ of the hot gas. We determine $\Delta S=S-S_0$ by taking the difference between $S$ and the entropy $S_0$ found in cosmological adiabatic simulations for haloes of the same mass. The temperature $T$ of the hot gas during the heating phase is determined from semi-analytic/semi-empirical modelling by assuming that heat absorption traces the accretion histories of supermassive BHs. Our findings suggest that supermassive BHs thermalise 1 to $3\%$ of their energy output in the surrounding gas. Our results suggest two regimes: (i) in elliptical galaxies and groups, active galactic nuclei (AGN) heat the gas much more rapidly than it can cool, generating the observed entropy excesses and quenching star formation when the accumulated heat is large enough to unbind the gas reservoir in the host halo; (ii) in galaxy clusters (at $M_{200}>10^{14}{\rm\,M}_\odot$), heating and cooling are in self-regulated equilibrium.
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Astrophysics of Galaxies

The MWA Interestingly Deep AStrophysical (MIDAS) Survey: Survey Description and First Data Release

We present the deepest MWA survey to date, targeting the GAMA9 and GAMA23 survey fields at 215.68 MHz. With a bandwidth of 30.72 MHz, the two images cover ${\sim}1250\text{ deg}^2$ for the GAMA9 field and ${\sim}850\text{ deg}^2$ for the GAMA23 field, with an angular resolution of ${\sim}60''$. The GAMA9 image was formed from 1 282 2-min snapshot observations (42.7 hours) and the GAMA23 image from 1 701 observations (56.7 hours) achieving depths of $0.923 \pm 0.003$ and $0.331 \pm 0.001$ mJy/beam at the field centres respectively. We processed the data with an updated version of the GLEAM-X pipeline tuned for deep surveys and make this MWA Deep Imaging Pipeline code public. Updates to the pipeline include automation of the observation downloading, calibration, and imaging along with optimisation of the CLEANing methods and parameters. Above $5\sigma$, we catalogue 53 419 and 80 407 radio components in the GAMA9 and GAMA23 fields respectively. We find that the completeness corrected source counts for both fields are in good agreement down to $25$-$50$ mJy with those from LOFAR and earlier MWA surveys. We demonstrate the utility of this survey by highlighting a few sources of particular interest and describing future science possible with this survey.
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All authors S. Paterson, N. Seymour, N. Hurley-Walker, T. J. Galvin, S. W. Duchesne, J. Morgan, T. M. O. Franzen

Astrophysics of Galaxies

Semiresolved Stellar Populations as Distance Indicators

Galaxy distances are central to our understanding of the Universe. Despite the success of existing approaches, independent and complementary methods remain valuable for testing systematic effects and extending the applicability range of different distance metrics. Here we demonstrate that the spectrum of an individual semi-resolved stellar population encodes direct information about its distance and that valuable distance constraints can, in principle, be obtained by combining multiple independent measurements. When applied to optical spectra of bulge of the Andromeda galaxy (M\,31), we derive a stellar population-based distance of 756$\pm$57 kpc ($\mu_0 = 24.39 \pm 0.15$), in agreement with state-of-the-art measurements. Crucially, semi-resolved stellar population distances does not require secondary calibrations, although its absolute scale remains conditional on the adopted stellar population models. Our findings provide a first assessment of the feasibility of deriving stellar population-based distance estimates from simple stellar population models, motivating further tests of the broader applicability and precision of the method.
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All authors Ignacio Martín-Navarro, Patricia Iglesias Navarro, Francesco La Barbera, Alexandre Vazdekis, Michael A. Beasley, Marc Huertas-Company, ChangHoon Hahn, Luis Peralta de Arriba, Isaac Alonso Asensio, Eirini Angeloudi, Miguel Cerviño, Katja Fahrion, Tereza Jerabkova, Jesús Falcón-Barroso, Sebastián F. Sánchez, Prashin Jethwa

Applied Physics

Quasi-normal-mode signatures of periodicity and hyperuniformity

Hyperuniform materials occupy an intermediate regime between periodic order and conventional disorder, characterized by a suppression of long-wavelength density fluctuations, commonly quantified by the structure factor. This characterization, however, relies on the statistical properties of an extended configuration or supercell representation and does not directly describe the resonant response of a finite structure, as typically encountered in scattering experiments. Here, we introduce the quasi-normal-mode spectrum as a complementary framework for characterizing the wave properties of finite stealthy hyperuniform materials. We analyze the complex eigenfrequencies of both periodic and stealthy hyperuniform structures over a range of the stealthiness parameter ($\chi$), and investigate how the spatial organization of scatterers is encoded in both frequency and spatial profiles of their quasi-normal modes. We find systematic changes in the quasi-normal modes spectrum as the degree of hyperuniformity is varied, revealing signatures that are not captured solely by the structure factor. In particular, the evolution of the resonant states provides a direct connection between structural correlations and the scattering response of finite systems. Our results establish quasi-normal modes as a real-space and open-system characterization of hyperuniformity and provide a unified framework for comparing discrete heterogeneous materials from the perspective of their scattering and resonant dynamics.
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All authors V. Romero-García, M. Martí-Sabaté, V. F. Dal Poggetto, L.M. García-Raffi, M. Lázaro

Soft Condensed Matter

Cell size and confinement drive asymmetric cell division through a cortical instability

Asymmetric cell division – in which a mother cell divides into two daughter cells of unequal size – is a fundamental problem in biology. It is believed that the asymmetry originates from the prior polarization of the mother cell. Here we show that division asymmetry can occur spontaneously even in unpolarized mother cells. Specifically, curvature-dependent active stresses in the cell cortex can lead to this symmetry breaking without any molecular polarity cue if the mother cell is confined within a restricted space. Either reducing the cell size or tightening mechanical confinement triggers the same spontaneous symmetry-breaking instability, in which the contractile ring slips off the equator to yield daughters of unequal volume. In the presence of a polarity cue, this instability cooperates with the cue to program the division asymmetry. The model prediction is compared with the imaging data of C. elegans embryogenesis, in which successive cell divisions in a confined eggshell lead to smaller and smaller cell sizes. The measured division asymmetry indeed increases as the cells shrink, and is further amplified when the embryo is mechanically compressed, both in agreement with the model prediction.
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All authors Da Gao, Guoye Guan, Chao Tang, Rui Ma

General Relativity and Quantum Cosmology

Scalar wave scattering by black holes embedded in dark matter halos

We study the scattering of massless scalar waves by static black holes embedded in dark matter halos. The halo is modelled by means of a Hernquist profile, for which the Einstein equations admit an exact solution. We analyse the scattering using null geodesics, the glory approximation, the partial wave expansion, and the complex angular momentum (CAM) method. The geometric analysis shows that the presence of the halo changes the light ring radius weakly but shifts the critical and glory impact parameters. The wave analysis shows that the characteristic black hole interference pattern is preserved, with halo compactness providing the leading correction and the halo scale radius playing a secondary role. For sufficiently compact halos, the environment also induces a sizeable gravitational redshift. Most of the displacement of the interference extrema can be reproduced by a vacuum Schwarzschild solution with an appropriately chosen $\omega M_{\rm BH}$. A non-vanishing residual, however, reveals a genuine halo contribution that cannot be absorbed into such an effective frequency shift. Finally, we perform the CAM reconstruction of the scattering cross section and find that only a few Regge poles are required to achieve high accuracy at large angles.
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Solar and Stellar Astrophysics

The quiescent states of V745 Sco and V3890 Sgr: VLT/X-shooter and Swift/XRT+UVOT observations

Symbiotic recurrent novae are symbiotic binaries in which multiple thermonuclear outbursts have been observed. Only four such systems are currently known in the Galaxy: T CrB, RS Oph, V745 Sco, and V3890 Sgr. They provide convenient laboratories for studying accretion and binary interaction in symbiotic novae during quiescence. We characterise the quiescent states of the less-studied systems V745 Sco and V3890 Sgr and compare their properties with those of T CrB and RS Oph. We analyse VLT/X-shooter spectra together with Swift/XRT and UVOT observations, supplemented by ground-based optical photometry and archival data. We determine the spectral types of the red-giant donors and compare the spectral energy distributions of the systems with those of single bulge giants of the same spectral type to investigate the properties of the accretion. We classify the donor stars in V745 Sco and V3890 Sgr as M7III and M6.5III, respectively. We derive reddenings and distances consistent with both systems belonging to the Galactic bulge. Both objects exhibit a significant ultraviolet excess relative to normal late-type giants, indicating ongoing accretion during quiescence. From this excess we estimate mass transfer rates of the order of $\sim 5 \times 10^{-8}\ M_{\odot}\ \mathrm{yr}^{-1}$, broadly consistent with the observed recurrence timescales. These results suggest that recurrent nova eruptions in V745 Sco and V3890 Sgr can be sustained by long-term accretion at approximately the present rate, without requiring an episode of enhanced accretion similar to that observed in T CrB.
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All authors Bor Jamnik, Ulisse Munari, Nicola Masetti, Gregor Traven, Manica Perko

High Energy Physics (Experiment)

Constraint on the Higgs boson width in the diphoton final state using signal-background interference in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The standard model Higgs boson, with a mass of 125 GeV, has a predicted decay width, $\Gamma_\mathrm{H}$, of 4.1 MeV. This Letter presents the first constraint on $\Gamma_\mathrm{H}$ obtained through the interference between the resonant H $\to$ $\gamma\gamma$ process and the continuum $\gamma\gamma$ production, both produced via gluon-gluon fusion. The analysis is performed using proton-proton collision data at $\sqrt{s}$ = 13 TeV, collected by the CMS experiment between 2016 and 2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. The observed (expected) limit on the Higgs boson width is $\Gamma_\mathrm{H}$ $\lt$ 92 (138) MeV at 95% confidence level. This is the most stringent constraint on $\Gamma_\mathrm{H}$ from on-shell Higgs boson measurements to date.
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Materials Science

Simulating Continuous-Rotation 3D Electron Diffraction: A Multislice and Bloch Wave Framework

To improve the agreement between measured and calculated intensities of three-dimensional electron diffraction (3D ED) experiments, a simulation pipeline is needed to assess and quantify the influence of various structural and experimental parameters. We present a computational pipeline, built upon the abTEM Python package, to simulate continuous-rotation 3D electron diffraction data based on either the Bloch wave or the multislice formalism. Multislice calculations in arbitrary orientations are achieved through large supercells and windowing. We investigate the convergence of key simulation parameters and test their consistency, establishing suitable parameters for accurate and efficient simulations. The pipeline's applicability and robustness are demonstrated through case studies on cubic silicon as well as stretched and sheared variants, analyzing the influence of electron kinetic energy, sample thickness, orientation, and symmetry on simulated diffraction intensities. Finally, we investigate a representative selection of seven compounds, including cubic $\mathrm{SrTiO_3}$, monoclinic $\alpha$-glycine $\mathrm{C_2H_5NO_2}$, and triclinic kyanite $\mathrm{Al_2SiO_5}$ to validate the method. This framework for the simulation of 3D electron diffraction data establishes an approach to investigate the dependence of diffracted intensities on experimentally relevant parameters which are difficult to systematically investigate in experiments.
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All authors Małgorzata K. Cabaj, Jacob Madsen, Toma Susi, Lukáš Palatinus, Paul B. Klar