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Friday 18 September

Solar and Stellar Astrophysics

Searching for Massive Remnant Planetary System Hosts with White Dwarf Gaia XP Spectra

Lou Baya Ould Rouis, J.J. Hermes, Pierre Bergeron et al. (+5 more)

Remnant planetary systems around massive white dwarfs ($M_{\rm WD} > 0.8\,{\rm M}_\odot$) are intrinsically rare and remain poorly characterized. As the evolutionary endpoints of intermediate-mass B- and A-type stars, these white dwarfs provide valuable constraints on the formation and survival of planetary systems around higher-mass progenitors. In the absence of large, dedicated spectroscopic surveys, extremely-low-resolution Gaia XP spectra provide a powerful means of identifying candidate metal-polluted white dwarfs. We obtained follow-up observations with low-resolution optical spectroscopy (R=500-4000) to search primarily for Ca II H & K absorption in massive, metal-polluted white dwarf candidates selected from Gaia XP spectra to increase the sample of massive remnant planetary system hosts among objects with effective temperatures below $\sim15{,}000$ K. We find that Gaia XP spectra recover metal-polluted white dwarfs efficiently, confirming 82$\pm$5% recovery of photospheric metals (59 of 72 targets) in high-confidence candidates of our sample (with classifier probability $P_{\rm DZ} > 0.65$). However, Gaia photometric masses derived from $G$, $G_{BP}$, and $G_{RP}$ broad-band photometry are not sufficient to identify the most massive systems, as reliable mass determinations require detailed metal-enriched atmospheric fits. We present a selection of cool white dwarfs confirmed to be both massive and metal polluted, demonstrating that Gaia XP spectra can substantially expand the sample of white dwarf exoplanet hosts. Our search led to the discovery of a new transiting debris system, SDSS J1624+5404, the 21st published system to date and eighth to show periodic transits.
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All authors Lou Baya Ould Rouis, J.J. Hermes, Pierre Bergeron, Simon Blouin, Stefan Arseneau, Tim Cunningham, Joseph A. Guidry, Ciarra Coston

Image and Video Processing

Model-Based Iterative Reconstruction with View-Dependent Detector Displacements for Cone-Beam CT

Doga Topcicek, Sharmin Majumder, Whitney A. Poling et al. (+4 more)

Detector shifting is used in industrial cone-beam computed tomography to reduce ring artifacts, but the resulting detector motion can vary nonuniformly across projection views and produce detector positions that cannot be represented by fixed offsets. Although analytical reconstruction can accommodate this motion, approaches that use projection interpolation or rebinning may limit spatial resolution and introduce artifacts. MBIR provides an alternative by representing the acquisition geometry explicitly within the reconstruction model. Existing separable distance-driven MBIR formulations assume fixed detector geometry across projection views and therefore cannot directly represent nonuniform motion in both detector dimensions, as this motion changes the voxel-to-detector mapping. We extend the separable distance-driven MBIR model to incorporate recorded horizontal and vertical detector displacements into the distance-driven overlap computation while leaving measured projections unchanged. Forward-projection validation achieved an NRMSE of 0.0338 across 1080 views. The proposed model achieved a 3D SSIM of 0.9404 and NRMSE of 0.0406, compared with 0.5396 and 0.1740 for fixed-detector MBIR. A second industrial dataset showed reduced structured artifacts compared with FDK.
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All authors Doga Topcicek, Sharmin Majumder, Whitney A. Poling, Dmitriy D. Bruder, Zhili Feng, Dali Wang, Xiao Wang

Audio and Speech Processing

Partial Accent-Control Editing in Frozen Speech Representations for Accent Conversion

Yangyang Qu, Michele Panariello, Massimiliano Todisco et al. (+1 more)

Accent conversion is the task of modifying a speech recording so that it sounds closer to a target accent while preserving linguistic content and other speaker-related characteristics. Most accent conversion systems use trained, generative models. Although they can induce target-accented speech, the strength of accent modification is not controllable at inference time, making it difficult to analyse how the strength of accent conversion affects source preservation. We propose Partial Accent-Control Editing (PACE), an accent conversion framework based upon the editing of frozen WavLM representations without the training of an accent-conditioned generator. A constrained edit is first applied to source WavLM features, which are then fused with target-accent reference features retrieved from non-parallel accent examples. Fusion weights are used to control the trade-off between accent conversion strength and the degradation of other source attributes. Using a suite of five metrics, and with the cost of accent-entangled speaker similarity, we show that PACE is substantially superior to a pair of competitive baselines in terms of both accent conversion and source preservation.
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All authors Yangyang Qu, Michele Panariello, Massimiliano Todisco, Nicholas Evans

Materials Science

Symmetry Classification of Multipolar Orders in Crystals: Theory, Property Tensors and Automated Analysis with MagSymMultipoles

Maxime Braun and Quintin N. Meier

Many structural and magnetic phases and properties of crystalline materials can be related to the ordering of electric and magnetic multipoles. Examples include ferroelectricity, linear magnetoelectricity, and altermagnetism. Determining the symmetry-allowed multipoles in a crystal is therefore useful for characterizing its ordered phases and physical properties. Here, we present a unified Cartesian framework for decomposing moment tensors of arbitrary rank into ordinary, toroidal, and poloidal multipoles, and for determining, from crystallographic and magnetic symmetry, their ferroic, antiferroic, and noncollinear arrangements within the crystal. We further establish the direct symmetry relationship between multipolar order and the allowed components of associated physical-property tensors in both relativistic and non-relativistic settings. We implement this methodology in MagSymMultipoles (https://mag-sym-multipoles.com), an interactive web application for calculating and visualizing symmetry-adapted electric and magnetic multipoles. The application uses magnetic symmetries both with and without spin-orbit coupling to derive the allowed multipoles as well as the underlying Cartesian moment tensors, making it easy to explore the connection between a given multipolar order and the corresponding physical response tensors. We demonstrate the approach for ferroelectric BaTiO3, antiferroelectric PbZrO3, magnetoelectric Cr2O3, and the altermagnets MnF2, MnTe, and Mn3IrSi. These examples demonstrate how our method allows us to obtain an intuitive picture linking the multipolar order of a material directly to its physical properties, thereby facilitating the interpretation of theoretical and experimental results.
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Instrumentation and Methods for Astrophysics

The optical high-resolution spectral archive of the HERMES spectrograph mounted on the 1.2m Mercator telescope

Hans Van Winckel, Saskia Prins, Gert Raskin et al. (+13 more)

Context. The HERMES spectrograph is a high-resolution, fibre-fed optical spectrograph of the 1.2m Mercator telescope operated from the Roque de los Muchachos observatory in Spain. HERMES started its scientific operations in June 2009 and has been the workhorse instrument since then. Regular instrument updates have been crucial. They have helped to ensure the continued provision of high-quality spectra. This will continue both now and in the future. Aims. With this contribution we review over 16 years of HERMES operations and we launch and introduce the archive to the interna- tional community at large. We describe the overall performances of the HERMES spectrograph and list the most important instrument upgrades since the start of the operations. We release about 150 000 high-resolution spectra to the community and describe global properties of the datarelease. We use a standard propriety period of 1 year with some exceptions. Methods. We used the German Astrophysical Virtual Observatory (GAVO) DaCHS platform to present the archive in a Virtual Ob- servatory (VO) compatible form with both an access via a dedicated webinterface, and via VO-compliant tools like PyVO, TOPCAT, Aladin etc. We illustrate the use in several worked-out examples to search and download the fully wavelength-calibrated, cosmic- cleaned and barycentric corrected 1D spectra. Results. With this contribution we provide the needed information of the data product and offer a reference paper for the users of the HERMES archive.
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All authors Hans Van Winckel, Saskia Prins, Gert Raskin, Jesus Perez Padilla, Wim Pessemier, Wim De Meester, Maarten Dirickx, Yves Frémat, Alain Jorissen, Holger Lehmann, Kwinten Missiaen, Maddalena Reggiani, Hugues Sana, Andrew Tkachenko, Bart Vandenbussche, Christoffel Waelkens

Sound

Spherical Harmonic Sliced Wasserstein Displacement Interpolation for Acoustic Source and Reflection Density Modeling

Yuancheng Luo

Spatial room impulse responses (SRIRs) capture directional distributions of acoustic sound-sources and their reflections. However, collecting SRIRs of moving sound-sources remains a challenge, requiring complex interpolations across measurements that account for multi-path spatial-temporal dynamics. This paper investigates the Wasserstein metric and displacement for evaluating interpolated SRIR echo densities in the spherical harmonic domain. We present novel sum-of-magnitude square expansions for efficiently fitting probability density functions, maximizing likelihood, inverse sampling, and computing spherical sliced Wasserstein interpolations. Experiments compare the Wasserstein displacements and metric to linear and geometric interpolations of SRIR image-source densities on a line-path, and demonstrate model-order reduction.
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Classical Analysis and ODEs

An Askey Scheme for Jacobi Systems of Mixed Type: Laguerre Limits of the First and Second Kinds and Hermite Limits

Manuel Mañas

An Askey-type confluence scheme is developed for Jacobi multiple orthogonal systems of mixed type, with $q$ row weights and $p$ column weights. Rescaling the Jacobi variable near $0$ and near $1$ produces Laguerre systems of the first and second kinds. A Hermite system with one Gaussian–gamma row and $q-1$ exponential convolutions is obtained from Laguerre of the first kind, directly from the second kind, and directly from Jacobi. Explicit limiting weights and orthogonal forms are given, together with convergence of their mixed moments. For each fixed index, the recurrence coefficients and the entries of the bidiagonal factors also converge in the limit to Laguerre of the first kind, under nonvanishing conditions. The Laguerre family of the second kind is described by additive gamma convolutions. A closed product formula for its moment determinants holds for arbitrary positive real shape parameters and near-diagonal row multi-indices, yielding explicit normality conditions. Its forms admit contour and Rodrigues representations with terminating hypergeometric components: a multiple Kampé de Fériet series for $A$, and at most $q+1$ Srivastava–Daoust series for each $B$-component when $q\ge2$. For the Hermite family, normality holds at every Laguerre-admissible index under the stated separation conditions, and these indices form an infinite set. Its components have finite Hermite expansions and terminating Srivastava–Daoust representations. The three routes give the same limiting moments and normalized components, the Jacobi one being a single limit and the other two iterated. An appendix treats several derivative rows, where the connection determinant vanishes beyond a finite index range, with exact rank loss and diverging components. The one-row reductions recover the classical multiple second-kind Laguerre and Hermite systems.
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Earth and Planetary Astrophysics

Rotational Mapping and Regional Atmospheric Retrievals of Variable Brown Dwarfs: Application to Luhman 16B and SIMP 0136

Ruizhe Wang, Heather A. Knuton, Julie Inglis et al. (+1 more)

We present a Bayesian framework for converting time-resolved spectroscopy into rotation-inferred regional spectra and atmospheric constraints for variable brown dwarfs. We derive an analytic mapping framework with evidence-optimized regularization and uncertainty propagation by marginalizing over physical parameters and model complexities. We provide methods for selecting characteristic spectral end-members from the inferred surface maps, and highlight the advantage of analyzing these rotation-inferred regional spectra over the disk-integrated time-resolved observations, while explicitly accounting for the geometric degeneracies inherent to rotational mapping. We apply this framework to published JWST/NIRSpec rotational monitoring of Luhman 16B and SIMP 0136. For both objects, we identify dominant spectral regions and retrieve regional variations in cloud structure, thermal gradients, and chemistry that are consistent with cloud radiative feedback. In addition, we demonstrate the importance of limb darkening in deriving surface maps. These results establish a statistically controlled method for linking rotational spectral variability to atmospheric heterogeneity and enable future rotational mapping and regional atmospheric studies of giant planet atmospheres.
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All authors Ruizhe Wang, Heather A. Knuton, Julie Inglis, Xianyu Tan

Quantum Physics

Cavity-QED analysis of InAs quantum-dot single photon production

W. W. Chow, S. Peana, D. I. Herman et al. (+6 more)

Cavity quantum electrodynamics is used to study the extent cavity enhancement affects single photon performance of an InAs quantum dot, in terms of emission rate, purity and indistinguishability at different temperatures. Parametric studies show a tradeoff between single photon production rate and purity, as well as between indistinguishability and purity. The results indicate the importance of quantum carrier-photon correlations that yield substantial corrections to mean-field treatments, especially at high light-matter coupling strength, where cavity enhancement is most effective.
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All authors W. W. Chow, S. Peana, D. I. Herman, K. Y. Lee, A. Cejan, C. Shang, G. Moody, J. E. Bowers, F. Jahnke

Human-Computer Interaction

Beyond Reactive Assistance: PV-Care Using Low-Density EEG and AI to Provide Proactive, Context-Aware Help for MCI

Simon L Liu and Manish Kumar Krishne Gowda

The growing elderly population gives rise to an urgent need for intelligent support systems, particularly for individuals with Mild Cognitive Impairment (MCI). This paper presents PV-Care, a proactive AI-driven assistance scheme that integrates wearable electroencephalogram (EEG) sensing with visual environmental perception to provide real-time, context-aware voice assistance for MCI users. Unlike traditional assistant systems that passively wait for user commands, PV-Care actively initiates helpful interactions based on the user's detected brain states, including Learning, Memory Recall, and Resting, using a novel deep neural architecture named Spatial and Frequency Refinement Network (SFR-Net). By combining EEG-based cognitive-state recognition with AI-based visual analysis, PV-Care generates structured "4W-UT" prompts to guide the output of large language models (LLMs). Simulation results and user studies validate the high accuracy of the proposed SFR-Net and the effectiveness of PV-Care's context-aware assistance. These results indicate that PV-Care is a feasible and promising solution for MCI caring.
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Mesoscale and Nanoscale Physics

Non-Hermitian impurity scattering in graphene: Boltzmann transport and thermoelectric response

Juan A. Cañas, Daniel A. Bonilla and A. Martín-Ruiz

We investigate charge and thermoelectric transport in monolayer graphene containing a dilute distribution of finite-range non-Hermitian scattering centers. The impurities are modeled as circular complex potentials, whose imaginary component describes local carrier loss or gain. By solving the Dirac scattering problem exactly within a partial-wave approach, we obtain the nonunitary scattering matrix and derive the transport and absorption cross sections, which separately characterize momentum relaxation and net carrier exchange with the environment. To connect the microscopic scattering problem with stationary transport, we formulate a semiclassical Boltzmann description in which an external reservoir compensates the equilibrium particle loss or gain. This leads to an effective relaxation time governed by both elastic momentum scattering and non-Hermitian flux exchange. Using the full energy-dependent relaxation time, we evaluate the Onsager coefficients and the resulting electrical conductivity, electronic thermal conductivity, Seebeck coefficient, Lorenz ratio, and electronic thermoelectric figure of merit. We find that weak gain increases the effective carrier lifetime and enhances both charge and heat conductivities, while absorption produces the opposite behavior. More importantly, gain enhances the magnitude of the thermopower and the electronic figure of merit, whereas loss suppresses them. The Lorenz ratio remains close to the Sommerfeld value, with non-Hermiticity mainly modifying its finite-temperature corrections. Our results show that non-Hermitian scattering provides an additional mechanism for controlling the energy dependence of carrier relaxation and, consequently, the thermoelectric response of graphene.
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Chemical Physics

cboamd: A Machine Learning Molecular Dynamics Framework for Vibrational Strong Coupling

Yifan Li, Roberto Car and Johannes Flick

Under vibrational strong coupling (VSC), molecular vibrations hybridize with an optical cavity mode to form polaritons, offering a route to modify chemical and material properties without external driving. In this work, we develop a machine-learning interatomic potential (MLIP) based framework to study VSC inside optical cavities. By using the cavity Born-Oppenheimer approximation and treating the photonic degrees of freedom as an effective electric field, we provide a framework that can describe VSC solely based on the electronic ground-state potential energy surfaces (PES), electronic dipole moment, and polarizability, all quantities obtained outside the cavity. We train PES, polarization, and polarizability models to drive the molecular dynamics (MD) simulations of systems under VSC. We demonstrate the approach for both a single CO$_2$ molecule and liquid CO$_2$, showing that the polarizability renormalizes the effective cavity resonance: at fixed cavity frequency this renormalization renders the Rabi splitting strongly asymmetric, while with renormalized cavity frequency the symmetric splitting is capped by polarizability screening. The collective Rabi splitting of the liquid is connected quantitatively to the single-molecule splitting involving the $\sqrt{N/3}$ orientational enhancement and the local-field enhanced effective charges of the coupled vibration, while the equilibrium pair structure of the CO$_2$ liquid remains unchanged. These simulations are the first MLIP-driven simulations of collective VSC in the condensed phase and open further pathways to the exploration of chemical effects under VSC.
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Earth and Planetary Astrophysics

Multiband Color Monitoring of 3I/ATLAS through Ground-Based Relay Observations

Ariel Graykowski, Bryce Bolin, Laura-May Abron et al. (+140 more)

We present multiband, long-baseline photometric observations of interstellar comet 3I throughout its 2025–2026 apparition using coordinated ground-based global relay observations. Our dataset combines measurements from professional observatories and citizen-operated Unistellar eVscopes distributed worldwide, providing dense temporal coverage from 2025 July 2 through 2026 April 1 and spanning the comet's pre- and post-perihelion trajectory. Broadband photometry was obtained in bandpasses equivalent to the Johnson–Cousins $B$ (436 nm), $V$ (545 nm), and $R$ (641 nm) filters and the Sloan $g$ (477 nm), $r$ (623 nm), and $i$ (763 nm) filters. The photometry was measured using projected aperture radii of approximately 10{,}000~km to provide a consistent probe of the inner coma across the heterogeneous dataset. We measure representative mean colors of $B-V=0.86\pm0.06$, $V-R=0.50\pm0.03$, $B-R=1.36\pm0.08$, and $g-r=0.58\pm0.08$, demonstrating a persistently red optical coma. Constant-color models provide an adequate description of the data, with little evidence for long-term color evolution with time or heliocentric distance despite substantial changes in the coma's brightness, gas production, and volatile composition. This suggests that the ensemble-averaged optical scattering properties of the coma remained relatively stable over the period sampled by our observations, even as other properties of the coma evolved. These observations provide the first densely sampled, apparition-long characterization of the broadband optical colors of an interstellar comet and establish a benchmark for comparison with future interstellar objects.
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All authors Ariel Graykowski, Bryce Bolin, Laura-May Abron, Franck Marchis, Martin Mašek, Filipp D. Romanov, Ahmed M. Abdelaziz, Dimitrios Athanasopoulos, Matthew Belyakov, Luca Buzzi, Michael W. Coughlin, Ergün Ege, Nicolas Erasmus, Thomas M. Esposito, Christoffer Fremling, Josep M. L. Garcia, Marek Husárik, Oleksandra Ivanova, Tarek M. Kamel, Sergey Karpov, Myung-Jin Kim, Tomasz Kwiatkowski, H.-J. Lee, Sofiia Mykhailova, Alessandro Nastasi, Dagmara Oszkiewicz, John W. Pickering, Alexey Sergeyev, Roman Telesnikov, Josep M. Trigo-Rodríguez, Al Alicea, Jin Beniyama, Otabek A. Burkhonov, Kamoliddin E. Ergashev, Y.H.M. Hendy, Jeong-Han Kim, Cheng-Han Hsieh, M. Emir Kenger, Thomas Lehmann, Igor Luk'yanyk, Ali Takey, Dušan Tomko, Murat Tekkesinoglu, Shane Winter, Joel Alonzo, Michael Beddo, Axel Bienefeld, Mario Billiani, John K. Bradley, Olivier Clerget, Sabine Cremer, Nicolas Delaunoy, José Donas, John Dunn, Jiří Dvořáček, Michael Edwards, Taj Entabi, Raffaele Esposito, Karen Fischer, Robert Foster, Edward Friday, Keiichi Fukui, Francois Gagnon, Matthieu Garisson, George Ghreichi, Patrice Girard, Tateki Goto, Michael Grant, Chris Greenfield, Bruno Guillet, Josef Hanus, John Harrison, David Havell, Kevin Heider, Kirt Hufstedler, Kachi Iwai, Maxime Johnson, Christian Joisten, Scott Kardel, Suzanne Kavic, Vamshi Kesireddy, Rachel Knight, David Koster, Jericho Kuehl, Ryuichi Kukita, Jan Kunc, Petri Kuossari, Alain Lambert, Scott Lancelle, Jean-Marie Laugier, Stephen Lawrence, Pedro Lemos, Jeffrey Linn, Joseph Llanes, Steeve Loisel, Gaël Lombart, Margaret A. Loose, Yohann Lorand, Chris Mahar, Scott Manley, Vincent Marcouiller, Sevastos Mastrogiorgis, Nicola Meneghelli, Mike Mitchell, Iaroslav Mokroguz, Jacques Molne, Fabrice Mortecrette, Ioannis Mytakos, Anouchka Nardi, Wataru Ono, James Owen, Larry Parchman, Bruce Parker, Michael Primm, Darren Rivett, Facundo Robles, Van Ruckman, Matthew Ryno, Nikolaj Schraufl, Jean-Pierre Schulz, Christoph Seidler, Lauren A. Sgro, Masao Shimizu, Francois Simard, Georges Simard, Bran Solo, Grant Sorenson, Marcelo Souza, David Swalander, Akimitsu Takahashi, Lydia Tamez, Petri Tikkanen, Bryan Tobias, Ian Transom, William Turnipseed, Charles Urban, Claudio Vantaggiato, Aad Verveen, Andrew Wendelborn, Stefan Will, Mark Wilson, Neil Yoblonsky, Wai-Chun Yue

Earth and Planetary Astrophysics

Comparative analysis of Neural Networks approaches for Initial Orbit Determination of Near-Earth Objects

Francesco Geroni, Roberto Paoli, Riccardo Massidda et al. (+1 more)

Initial Orbit Determination (IOD) from Very Short Arcs (VSAs) remains one of the most challenging open problems in asteroid surveillance and celestial mechanics. Classical methods require angular observations spanning a sufficient fraction of the orbit, and become ill-conditioned or fail outright when only a single observing night is available, as is the case for most newly discovered Near-Earth Objects (NEOs). We present a comparative analysis of two Neural Network (NN) models that attack the ranging problem directly: both ingest a triplet of time-tagged angular measurements $(t_i,\alpha_i,\delta_i)$, $i=1,2,3$, from a single VSA and predict the geocentric range and range-rate $(\rho,\dot\rho)$, thus completing the orbital state vector. The first is a Multi-Layer Perceptron trained on a purely data-driven objective; the second augments it with a physics-informed loss. Both are trained, under an object-disjoint partition, on a sample of the $568\,127$ VSAs of $39\,031$ real NEOs available in the NEODyS-2 catalogue. Each model returns an estimate on every arc by construction, so we assess instead whether that estimate is dynamically admissible: on a held-out test set of $56\,773$ arcs the physics-informed model places $85.1\%$ of its predictions inside the admissible region, against $76.5\%$ for the data-driven baseline, whereas Gauss's and Laplace's methods return a solution on only $45.0\%$ and $47.3\%$ of the same arcs and collapse onto the degenerate root in about nine of those cases out of ten. A stratified analysis over proper motion and true range shows that the physics-informed objective is not uniformly superior to the baseline: it trades a longer error tail for admissibility and for a marked advantage on the fast, nearby arcs that are operationally the most relevant.
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All authors Francesco Geroni, Roberto Paoli, Riccardo Massidda, Giacomo Tommei

Chemical Physics

ReaxKit: A Modular Python Toolkit for Preparing, Parsing, and Analyzing ReaxFF Molecular Dynamics Simulations

Ali Mohammadi Dinani, Alireza Sepehrinezhad, Anirban Phukan et al. (+7 more)

Empirical reactive force field (RFF) molecular dynamics enables atomistic simulation of bond breaking, bond formation, charge redistribution, and structural evolution in chemically complex systems. The ReaxFF method is arguably the most popular and transferable of the currently available RFF methods. However, routine use of ReaxFF often requires substantial manual effort to prepare inputs, interpret engine-specific outputs, organize simulation artifacts, and develop custom analysis scripts, limiting reproducibility and scalability. Here, we present ReaxKit, a modular Python toolkit for preparing, parsing, analyzing, and managing ReaxFF molecular dynamics simulations. ReaxKit uses a separation-of-concerns architecture that distinguishes engine-specific input/output handling, canonical domain data models, scientific analysis, workflow orchestration, presentation, storage, and graphical interaction. Engine adapters convert outputs from supported simulation environments into typed, engine-independent data structures, allowing analysis modules to operate independently of native file formats. User requests are executed through consistent command-line, functional Python, and browser-based graphical interfaces, while a dedicated workspace preserves raw data, normalized datasets, analysis settings, results, logs, caches, and provenance information. Representative applications demonstrate the breadth of the toolkit, including automated generation of elastic and equation-of-state training data from Materials Project structures and mechanical properties, characterization of active sites and local structural environments, and execution of simulation campaigns through YAML-defined study workflows. These capabilities show that ReaxKit supports all essential stages of the ReaxFF workflow.
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All authors Ali Mohammadi Dinani, Alireza Sepehrinezhad, Anirban Phukan, Asma Ul Hosna, Jupjeet Dhingra, Mozhdeh Mirakhory, Seyed Mahmoud Mortazavi, Yun Kyung Shin, Swarit Dwivedi, Adri C.T. van Duin

Cryptography and Security

The Supersingular Isogeny Problem in Time and Memory $p^{1/3+o(1)}$, Unconditionally

José Luis Delgado

Given a supersingular elliptic curve $E/\mathbb{F}_{p^2}$, the $\mathsf{OneEnd}$ problem asks for a non-scalar endomorphism of $E$. By known reductions, solving this problem also solves the supersingular endomorphism ring and isogeny problems. Wesolowski obtained exponent $1/3$ under an assumption on the factorization of a small degree, whereas the previous unconditional exponent was $2/5$. We give a Las Vegas algorithm, analyzed without a smoothness heuristic, with expected time and memory \[ p^{1/3}\exp\bigl(O(\sqrt{\log p\,\log\log p})\bigr) = p^{1/3+o(1)}. \] The algorithm fixes in advance a family of degrees that are products of small primes. Known counting results provide many isogenies of these degrees from curves to their Frobenius conjugates, and a collision estimate shows that the isogenies occur on sufficiently many distinct curves for a random walk to reach one of them. From such a curve, the algorithm splits a degree into two parts, enumerates two lists of shorter isogenies, and matches their targets to obtain an isogeny to the conjugate, whose composition with Frobenius gives the required endomorphism.
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Functional Analysis

On the dynamics of Toeplitz operators over Bergman spaces

Othman Abad

We investigate the hypercyclicity of Toeplitz operators on the Bergman space $L_{A}^{2}(\mathbb{D})$ with symbols of the form $\Psi(z) = \gamma\bar{z}+\psi(z)$, where $\gamma \in \mathbb{C} \setminus \{0\}$ and $\psi$ is analytic on an open neighborhood of the closed unit disc $\overline{\mathbb{D}}$. Our approach bypasses the classical Hardy space techniques (reproducing kernel linear combinations, Nevanlinna factorization) by directly solving the integro-differential resolvent equation arising from the Bergman projection. A key winding number argument shows that for sense-reversing symbols ($|\gamma| > \sup_{z \in \overline{\mathbb{D}}} |\psi'(z)|$), the symbol's image $\Psi(\mathbb{D})$ is contained in the point spectrum of $T_\Psi$. In the tridiagonal case $\Psi(z) = a\bar{z}+b+cz$, we fully resolve the longstanding eigenvector completeness problem by linking the recurrence coefficients to a rotated Favard spectral measure on the major axis of the symbol's ellipse. Combined with self-commutator positivity, this establishes an unconditional, exact necessary and sufficient characterization of hypercyclicity: $T_\Psi$ is hypercyclic if and only if $|a| > |c|$ and $\Psi(\mathbb{D})$ intersects both the unit disc and its exterior, completely eliminating the $(3+\sqrt{2})$ restriction of previous literature.
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Number Theory

$\mathbf{Bad}(\mathbf{r};\mathbf{s})$ is Hyperplane Absolute Winning

Chengyang Wu

Given an $m$-dimensional weight $\mathbf{r}$ and an $n$-dimensional weight $\mathbf{s}$, we prove that the set of $(\mathbf{r};\mathbf{s})$-badly approximable $m\times n$ matrices is hyperplane absolute winning on $\mathbb{R}^{m\times n}$. This fully answers a question \cite[Question 8.2 (iii)]{Kl} of D. Kleinbock in 1998.
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Optics

Optical Mode Sorting with a Programmable Diffractive Neural Network

Qian Zhang, Shiyue Chen and Juergen W Czarske

Programmable diffractive optical processors are particularly attractive for spatial light manipulation because their optical transformations can be dynamically reconfigured and adapted without modifying the physical hardware. However, their practical performance is often limited by the gap between simulation and experiment caused by optical aberrations, alignment errors, and nonideal phase responses. In this paper, we introduce a hybrid optimization framework that combines high-dimensional numerical design with low-dimensional hardware-in-the-loop calibration, enabling programmable diffractive optical networks to compensate experimentally for mismatch without retraining their underlying optical transformations. We demonstrate a programmable optical diffractive neural network (ODNN) designed by back-propagation to spatially sort six linearly polarized modes supported by a multimode fiber. The experimental distortions are represented using a truncated Zernike basis with only 19 correction coefficients per layer. These coefficients are optimized directly on the physical system using stochastic parallel gradient descent, avoiding re-optimization of the full pixelated phase masks. Experimentally, the proposed calibration yields an SNR improvement of approximately 3.26 dB, and a decrease in amplitude error of 0.04. This separation of high-dimensional optical-function design from low-dimensional physical calibration provides a scalable route towards adaptive and reconfigurable spatial-mode processors for optical router on spatial modes and wavelengths, programmable photonic computer systems and quantum information processing.
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Social and Information Networks

Auditing bipartite motif interpretations: a worked example with conservation checks and open-path decomposition

Tengfei Shao

Motif profiles of bipartite agent-object networks, such as tourist-site visits and customer-item transactions, are read as evidence about structural roles and about differences between networks, often without asking what the two degree sequences already fix. In a simple bipartite graph the induced k-fan count on one node type is a sum of degree combinations, so it has zero variance under a null that preserves both degree sequences. We apply this known result to a reconstructed tourism rating network of 17 tourists, 80 sites and 637 edges, the sole inferential worked example, and, as a provenance-limited illustration, to published motif-instance aggregates over 36 monthly luxury customer-item networks. The four fan classes are exact functions of the degree sequences: in the tourism network the raw fan counts and the size-3 two-fan ratio (84.7% fan-out) restate those sequences. The published luxury counts require at least 89,502 customer-item edges against 26,451 reported transactions, so their 99.8% fan-in is reported as a descriptive value only. Against a hard bipartite configuration null, the four-cycle count is degree-consistent (z about +1.0) and the open path is deficient (z about -5.8) by 2,243 instances, 2.4% of the null mean; the deficit survives every leave-one-tourist-out re-run (z -4.5 to -8.1). An exact identity splits it at the point estimate into 64.4% mixing and 35.6% four-cycle, but that split is not an attribution: the observed mixing term lies below all 500 null samples, the two components are almost collinear under the null (r = 0.968), and the mixing share ranges from 36.6% to 116.5% under leave-one-tourist-out deletion. The deficit is extreme relative to the sampled null, while its class-level interpretation is undetermined and unstable. We give a four-step pre-interpretation check and a reference implementation.
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High Energy Physics (Phenomenology)

Charged lepton flavor violating decays and $(g-2)_{e_a}$ in an extended standard model with singlet and triplet leptoquarks

L.T. Hue, N.V. Hop, Vo Quoc Phong et al. (+1 more)

We study the anomalous magnetic moments of charged leptons and their lepton flavor-violating decays in a Standard Model extension containing one $SU(2)_L$singlet and one $SU(2)_L$ triplet scalar leptoquark. Our results reveal significant correlations among $\Delta a_{e,\mu}$ and the decay rates of $e_b\to e_a\gamma$, and $h,Z\to e_b e_a$. In particular, the branching ratios $\mathrm{Br}(e_b\to e_a\gamma)$ and $\mathrm{Br}(h,Z\to e_b e_a)$ exhibit significant correlations. The model cannot simultaneously accommodate sizable values of $|\Delta a_e|=\mathcal{O}(10^{-13})$ and $|\Delta a_\mu|=\mathcal{O}(10^{-10})$. For $|\Delta a_\mu|=\mathcal{O}(10^{-10})$ and $\mathrm{Br}(\mu \to e\gamma)>10^{-15}$, the decay rates are suppressed to $\mathrm{Br}(\tau \to e\gamma)<\mathcal{O}(10^{-12})$ and $\mathrm{Br}(h\to \tau e)<\mathcal{O}(10^{-6})$, while the remaining ones can reach the forthcoming experimental sensitivities. Conversely, for $|\Delta a_e|=\mathcal{O}(10^{-13})$, one obtains the suppressed decay rates $\mathrm{Br}(\tau \to \mu \gamma)<\mathcal{O}(10^{-11})$ and $\mathrm{Br}(h\to \tau \mu)<\mathcal{O}(10^{-7})$.
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All authors L.T. Hue, N.V. Hop, Vo Quoc Phong, N.H.T. Nha

Machine Learning

COMPLEX: A Closed-Form Certified Embedding of Multiparameter Persistence Modules

Sushovan Majhi, Atish Mitra, Žiga Virk et al. (+1 more)

Every multiparameter persistence vectorization we know of carries a one-sided Lipschitz upper bound and nothing below it: without a lower gauge there is no sense in which the features are faithful, and no per-prediction guarantee can be built on them. This paper supplies the missing side. COMPLEX is a closed-form, training-free embedding of multiparameter modules – slice the module along a fixed near-diagonal net, embed each slice barcode by the certified PLACE/PALACE landmark map, concatenate. Under a checkable witnessing-slice coherence condition, holding on 100% of audited pairs on Orbit5k, a single slice carries a closed-form lower gauge: separated modules stay separated in the embedding. With the standard upper bound this gives, to our knowledge, the first two-sided distortion bound for a multiparameter feature map, making faithfulness measurable. Measuring it, we find the floor tight within a small factor of realized distances yet operationally local: an RBF-SVM reaches 91% where 1-NN reaches 78% on the same features. Local per-prediction certification therefore fails for a structural reason common to every landmark embedding whose lower gauge is witnessed by one coordinate. With no learned embedding and no held-out calibration – only a cross-validated SVM head – COMPLEX sets the state of the art on both Orbit benchmarks (91.95% on Orbit5k, 92.98% on Orbit100k), level with or above Euler-characteristic surfaces and above transformers and graphcode. On graphs it exceeds GRIL on all four shared molecular benchmarks with one fixed configuration, including the only multiparameter method to clear COX2's majority baseline by more than three points. Closed-form selection – of the landmark radius, the kernel (certificate-preserving), and the bifiltration set – buys further accuracy; gradient-shaped adaptation buys none.
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All authors Sushovan Majhi, Atish Mitra, Žiga Virk, Pramita Bagchi

Analysis of PDEs

Ekman Boundary Layers Under Transport Noise

Daniel Goodair and Szymon Sobczak

We consider a 3D rotating Navier-Stokes equation with transport-stretching noise, posed between two horizontal plates, and study the joint limit of vanishing vertical viscosity and rapid rotation. Our driving noise depends only on the horizontal coordinates and its vertical component vanishes with the viscosity. Provided that the initial data is purely horizontal, we construct martingale weak solutions which converge in $L^2_{\omega}L^\infty_tL^2_x$ to the layered strong solution of a 2D stochastic Navier-Stokes equation with damping. The damping coefficient is dependent on the limit of the ratio between vertical viscosity and inverse rotation rate.
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Quantum Physics

Selection rules for pinned and quasipinned occupation numbers with degeneracy

Robin Reuvers

When the natural occupation numbers of a fermionic state saturate a generalized Pauli constraint, the state obeys a selection rule: only those configurations of natural orbitals that saturate the constraint themselves contribute. Pinning thus singles out an active space. The selection rule was proved for non-degenerate occupation numbers; for degenerate ones it was conjectured, and proved for one saturated constraint under an assumption checked only for the constraints known at the time. Here, it is proved for every generalized Pauli constraint, with no assumption, and also in the spin-adapted setting. The rule can only fail for the ordering constraints $\lambda_j\ge\lambda_{j+1}$. Several saturated constraints are served by one basis whenever their common zero face contains a non-degenerate point. In practice, occupation numbers are quasipinned rather than pinned, and the rule survives with an explicit error bound.
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Materials Science

Insights into the long-standing controversy over sound velocities in lizardite

Chenxing Luo, Timothy Liao, Hongjin Wang et al. (+1 more)

Serpentine minerals are abundant H-bearing phases in the upper mantle and play a central role in water transport in subduction zones. Lizardite is the low-temperature polymorph expected in cold slabs and shallow serpentinized mantle. Using an ab initio thermoelastic framework combining density-functional theory with the r2SCAN meta-GGA and the quasiharmonic approximation, we calculate its compression curve, elastic tensor, and acoustic velocities at 300 K. r2SCAN reproduces the measured compression curve and equilibrium volume to within 0.2%. Weak interlayer hydrogen bonding gives rise to pronounced axial softening, with $C_{33} \simeq 0.21C_{11}$ and $C_{44} \simeq 0.13C_{66}$ at 0 GPa. Solving the Christoffel equation over all propagation directions, we construct the velocity density of states (VelDOS), which reveals a high density of slow acoustic modes and other directional features obscured by Voigt-Reuss-Hill (VRH) aggregate averages. Reported experimental velocities preferentially sample the slower portion of this distribution rather than clustering near the VRH values, a correspondence consistent with subtle crystallographic texture or preferential orientation not resolved experimentally. Thus, the appropriate seismic-velocity endmember for lizardite depends on its orientational state, and reliance on VRH velocities alone may lead to overestimation of the degree of serpentinization when seismic observations preferentially sample slow crystallographic directions. Direction-resolved single-crystal measurements and aggregate measurements with independently quantified texture would provide direct tests of this interpretation.
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All authors Chenxing Luo, Timothy Liao, Hongjin Wang, Renata M. Wentzcovitch

Computation and Language

DiaVLo: Diagnosing Behaviours of Vision-Language Models

Lorenzo Corti and Jie Yang

Vision-language models (VLMs) rely on storing and transferring appropriate information across their sub-components. Verifying that the VLMs exhibit desired behaviours, while avoiding harmful ones, is central to their reliable deployment. Yet, methods that identify VLM behaviours remain scarce. We present DiaVLo, a diagnostic framework that leverages human curation and VLMs' generation capabilities to construct specifications of desired and observed VLM behaviours, surfacing potential misalignments. Beyond this, DiaVLo also provides causal estimates to identify the most influential concepts steering VLM behaviours. We evaluate DiaVLo on several open-source VLMs under both classification and generation conditions. Our experiments show that DiaVLo produces behaviour labels that correlate with model performance and provide context for measured performance. DiaVLo surfaced behaviours that are clearly aligned and misaligned, alongside patterns in how VLMs perceive, organise, and prioritise concepts.
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Statistical Methodology

RKHS-Based Inference for Nonlinear Granger Causality via Conditional Centering

Yuhan Tian, Adam Waterbury and Marie-Christine Düker

Granger causality is commonly formulated through linear prediction in vector autoregressive models, limiting its ability to detect nonlinear predictive relationships. We propose a reproducing kernel Hilbert space (RKHS)-based test for nonlinear Granger non-causality in conditional mean for nonlinear autoregressive processes. The key idea is a conditional-centering decomposition of the target regression function into an own-history component and an orthogonal component capturing the additional predictive contribution of the potential source history. Non-causality is characterized by the vanishing of the latter component. The own-history component is estimated by kernel ridge regression, and the residuals are embedded in a second RKHS using a conditionally centered kernel. This yields an RKHS-valued residual moment whose squared norm forms the test statistic. We establish a weighted chi-square null limit and consistency against fixed alternatives for the population-centered statistic. An empirically centered version is shown to retain the null limit and enables spectral calibration of critical values and $p$-values without resampling. Simulation studies demonstrate accurate size control and power against nonlinear alternatives, and real-data applications illustrate the usefulness of the method for detecting nonlinear predictive relationships in time series.
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Optics

All-Optical Control over Nonlocality for Ultrafast Image Processing with an Excitonic Metasurface

Bernardo S. Dias, Romain Tirole, Michele Guizzardi et al. (+4 more)

Image processing lies at the foundation of many modern technologies, such as augmented reality and autonomous driving, yet conventional digital approaches remain energy-intensive and limited in speed. Nonlocal metasurfaces - 2D structures engineered at the nanoscale to support delocalized, dispersion engineered resonances - provide a fast, energy-efficient and ultrathin platform to perform image processing directly on the light path. Introducing tunability in this platform is an outstanding challenge, and would enable dynamic real-time control over the implemented processing operation, facilitating flexible integration into adaptive and multifunctional photonic architectures. Here, we demonstrate optically tunable edge detection at ultrafast speeds by integrating a dielectric nonlocal metasurface with multilayer WS2, whose strong exciton-driven optical response enables dynamic control of the metasurface nonlocality at sub-ps speeds. Using resonant optical pumping of the A-exciton in WS2, the metasurface transfer function is rapidly switched from edge detection to bright-field imaging by tuning its spatial nonlocality. Operating in the visible spectral range at a wavelength around 700 nm, the device shows ultrafast switching times and reaches an amplitude modulation depth of 11.5 dB for normal incident light. This approach provides a reconfigurable, ultrathin, all-optical platform for adaptive optical computing systems and highlights the potential of the highly nonlinear properties of 2D materials for active metasurfaces at ultrafast speeds.
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All authors Bernardo S. Dias, Romain Tirole, Michele Guizzardi, Andrea Cordaro, Albert Polman, Andrea Alù, Jorik van de Groep

Machine Learning

Abstention and Noise Filtering: Two Missing Primitives of Softmax Attention

Richard Zhe Wang

Softmax attention has two structural gaps. A head cannot abstain, because its weights sum to one, so it outputs something even when nothing is relevant. Nor can it filter what it reads, because its output is a weighted average of value vectors, passing interference as faithfully as signal. We call these missing primitives abstention and noise filtering. Recent studies report that gating the value pathway improves pretraining but attribute the gain to different causes. We show that a value gate partly supplies both primitives, which unifies the reported causes as views of one gain. We give each primitive its own mechanism in matched models of 10M to 350M parameters and measure what each contributes. The gain from gating is almost entirely abstention at 10M, whereas by 350M filtering contributes as much as abstention, so what a study observes depends on its scale. The two benefits are largely additive, with a small overlap. A gate determined by each value alone leaves the attention sink in place, whereas a query-controlled mechanism removes it. Injecting interference into the value reads shows that abstention and filtering protect against it in distinguishable ways. The same patterns appear in pretrained models up to 20B parameters.
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Group Theory

On Shalev's Quantitative Version of Thompson's Conjecture

Ohad Sheinfeld

The classical Thompson's conjecture asserts that in any finite nonabelian simple group $G$, there exists a conjugacy class $S$ whose square is equal to the entire group. Shalev (Annals Math., 2009) conjectured that a much stronger quantitative version holds: there exists $\epsilon > 0$ such that for any conjugacy class $S$ with $|S| \geq |G|^{1-\epsilon}$, we have $G \setminus \{1\} \subseteq S^2$. While the conjecture turns out to fail in general, we prove a close variant of the conjecture over $\operatorname{PSL}_n(2)$: There exist $\epsilon>0$ and $N \in \mathbb{N}$ such that for all $n\geq N$, every conjugacy class $S\subseteq\operatorname{PSL}_n(2)$ with $|S|\geq|\operatorname{PSL}_n(2)|^{1-\epsilon}$ satisfies $\{x\in\operatorname{PSL}_n(2):\operatorname{supp}(x)\neq1\}\subseteq SS^{-1}.$ On the other hand, we show that for each $\epsilon>0$, there exist conjugacy classes $S \subset \operatorname{PSL}_n(8)$ of size $>|\operatorname{PSL}_n(8))|^{1-\epsilon}$ for which $SS^{-1}$ misses even elements with support size linear in $n$. In addition, for every odd $n \ge 5$, we construct an inverse-closed normal set in $\operatorname{PSL}_n(5)$ with fixed positive density whose square misses a nonidentity element. This answers on the negative a question of Shalev (ECM, 2021) and disproves a conjecture of Pyber (Kourovka notebook, 2022).
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