Mathematical Physics
Homotopies in Batalin-Vilkovisky Formalism
Branislav Jurčo, Ján Pulmann and Martin Zika
We review the notion of homotopy of
quantum master actions in
geometric Batalin-Vilkovisky formalism. Then we construct new examples of such homotopies, coming from renormalization group flow and non-infinitesimal changes of gauge fixing. Finally, we use the field redefinitions given by these homotopies to construct spans of
quantum master actions with isomorphic effective actions.
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High Energy Physics (Theory)
Revisiting fermion bound states in baby Skyrme background with Dzyaloshinskii Moriya interaction
Arvind Rajaraman, Chao-Hsiang Sheu and Alexander Stewart
In this paper, we investigate a
fermion coupled to a Skyrme model in $2+1$ dimensions, where the Skyrmion is stabilized by the Dzyaloshinskii-Moriya and Skyrme interactions under a quadratic potential. This framework interpolates between the
magnetic Skyrmion at the critical coupling and the baby-Skyrme limit. The Dirac equation is studied both analytically in a non-relativistic reduction and numerically for the full relativistic spectrum, and the parameter region admitting states bound to the Skyrmion is determined. Localized solutions exist only for electrically charged
fermions with positive charge and negative angular momentum, and are absent for neutral
fermions. The lowest bound state in each angular momentum sector is characterized as a function of the
fermion mass, charge, and the coupling $h$ to the Skyrmion isospin, and its behavior is compared across the
magnetic, baby, and mixed Skyrmion backgrounds. The resulting
fermion–Skyrmion composite constitutes an electrically charged state bound to a topological texture, providing concrete signatures for potential future transport and scattering measurements in
chiral magnets.
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General Relativity and Quantum Cosmology
A rotating black hole in a Hernquist dark matter halo: horizon geometry, thermodynamics, and quantum emission
A. A. Araújo Filho, Arun Kumar, N. Heidari et al. (+3 more)
We investigate the geometrical, thermodynamic, and
quantum emission properties of a rotating black hole immersed in a Hernquist dark matter
halo. Starting from a static black hole spacetime surrounded by a Hernquist distribution, we construct its rotating counterpart through the noncomplexification formulation of the Newman-Janis
algorithm and analyze the modifications induced by the independent
halo parameters $\rho$ and $r_s$ and the rotation parameter $a$. The horizon structure is determined from the roots of the radial function $\Delta(r)$, while the stationary limit surfaces and the corresponding ergoregions are obtained from the condition $g_{tt}=0$. We show that the Hernquist contribution displaces the outer event horizon toward larger radii and modifies the size of the ergoregion, whereas rotation controls the oblateness of the horizon and the strength of frame dragging. We further derive the surface
gravity, Hawking temperature, Bekenstein-Hawking
entropy, and heat capacity. The
quantum tunneling rate is obtained from the Hamilton-Jacobi method, leading to the corresponding occupation number and a thermal estimate of the particle creation density. Finally, we estimate the Hawking luminosity and evaporation timescales within a Stefan-Boltzmann approximation. All standard Kerr and Schwarzschild results are recovered in the appropriate limiting cases.
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All authors A. A. Araújo Filho, Arun Kumar, N. Heidari, C. F. S. Pereira, Amilcar R. Queiroz, V. B. Bezerra
Chemical Physics
ElemeNet: Multiscale Molecular Machine Learning with Uncertainty Quantification Across the Periodic Table
Jacob W. Toney, Samir Darouich, Yiran Wang et al. (+3 more)
Advances in deep learning architectures and representations have enabled ML-driven chemical property prediction, but state-of-the-art (SOTA) models have remained largely confined to independent codebases and lack support for diverse chemical species. This work introduces ElemeNet, a unified, general-purpose software package for molecular machine learning. The ElemeNet software package enables the training of advanced ML models for diverse properties and
datasets with an enlarged range of elemental compositions. We define molecular representations compatible with elements 1-100, supporting diverse organometallic and biological systems in addition to organic chemistry already well-served by the Chemprop ML toolkit. As well as more common atom-, bond-, and molecule-level predictions, we introduce moiety predictions. We also natively define optional conditioning on charge and
spin states. Advanced E(3)-equivariant and
transformer architectures are supported, as well as classical 2D models, with all classes including built-in uncertainty quantification through deterministic and statistical measures. We
benchmark our protocols for ML model training against representative
datasets from organic, inorganic, coordination, and biological chemistry, achieving competitive and SOTA performance relative to literature baselines and favorable scaling to millions of molecules. The entire workflow is exposed through a concise command-line interface, lowering the barrier to entry for non-expert users. We anticipate ElemeNet will empower non-computational researchers to leverage modern deep learning methods across the chemical and physical sciences.
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All authors Jacob W. Toney, Samir Darouich, Yiran Wang, Aaron G. Garrison, Johannes Kästner, Heather J. Kulik
High Energy Physics (Phenomenology)
A multi-differential constraint map for quarkonium suppression mechanisms in high-multiplicity pp and pPb collisions
Renato Campanini
The multiplicity-dependent suppression of $\Upsilon(nS)$ excited states in high-multiplicity $pp$ and $p$Pb collisions is analysed using publicly available CMS and LHCb data; preliminary CMS Physics Analysis Summary results in $p$Pb and light-ion collisions are used only as supporting cross-system evidence. Six complementary differential constraints are considered: cone isolation, azimuthal-sector equivalence, transverse sphericity, transverse-momentum ordering, forward-$E_T$ long-range correlation, and the pPb/Pbp forward-backward asymmetry. Taken together, these constraints disfavour mechanisms controlled solely by local track density or by total multiplicity, and are consistent with an early, globally correlated,
topology-sensitive suppression pattern. The characteristic multiplicity scale at which suppression sets in is independently consistent with the onset of a qualitative change in soft-sector behaviour identified by Campanini and Ferri \cite{CampaniniFerri2011} from inclusive charged-particle observables. The result is a data-driven constraint map consistent with an early, coloured pre-hadronic environment, possibly involving a deconfined stage.
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Cosmology and Nongalactic Astrophysics
Square Kilometer Array Synergies for the Epoch of Reionization and Cosmic Dawn
Anirban Chakraborty, Tirthankar R. Choudhury, Kanan K. Datta et al. (+15 more)
Synergies with other instruments will be essential in making, verifying, and interpreting a detection of the
cosmic 21-cm signal from the Epoch of Reionization (EoR) and
Cosmic Dawn (CD) with the Square Kilometer Array (SKA)
telescope. Such synergies can (i) provide prior information about
galaxies and the intergalactic medium (IGM) during the EoR/CD; (ii) pave the road to a first 21cm detection by mitigating foregrounds and systematics through cross-correlations; and (iii) give complimentary physical insights into the
galaxy – IGM connection. Here we review the current state of synergies and discuss what observations will best compliment SKA-low EoR/CD observations.
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All authors Anirban Chakraborty, Tirthankar R. Choudhury, Kanan K. Datta, Pratika Dayal, Jiten Dhandha, Samuel Gagnon-Hartman, Sambit K. Giri, Adelie Gorce, Caroline Heneka, Anne Hutter, Barun Maity, Suman Majumdar, Andrei Mesinger, Kana Moriwaki, Chandra Shekhar Murmu, Yuxiang Qin, Shintaro Yoshiura, Erik Zackrisson
Quantum Physics
Revisiting the Page curve and its moments. A combinatorial approach
Gero von Gersdorff
We revisit the calculation of the von Neumann (or "
entanglement")
entropy of a subsystem of a pure
quantum state, under the assumption that the latter is drawn at random from a uniform distribution on the full
Hilbert space. We derive simple and closed expressions for all power moments, from which the moments of the
entropy can be computed by simple differentiation. Our approach (different from the usual one based on random
matrix theory and Laguerre
polynomials) makes use of Schur-Weyl duality and the character theory of the symmetric group $S_N$ . The paper is self-contained, providing all the necessary mathematical background.
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Earth and Planetary Astrophysics · Cross-listed from cs.LG
Physics-informed Conditional Normalizing Flows for Angles-only Cislunar Orbit Determination
Walther Litteri and Massimiliano Vasile
Generative Astrodynamics is advanced in this work by extending generative modelling to an orbit determination problem in the cislunar environment. The task is formulated as conditional density estimation, aiming to infer the probability distribution of the initial state from angles-only measurements over short observation arcs. A normalising flow is trained on perturbed topocentric observations from Near Rectilinear
Halo Orbits, enabling a flexible and potentially
multimodal posterior representation. Given new measurements, the learned density is sampled to generate statistically consistent and physics-informed state hypotheses. These estimates are refined via nonlinear least-squares minimisation, providing a competitive warm start for classical
algorithms.
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Materials Science
Prebiotic Chemistry Assemblies of L-Cysteine on Defect-Free Pyrite Terraces
Adriana E. Candia, Sindy J. Rodríguez, Vanina G. Franco et al. (+3 more)
Wächtershäuser's theory proposes iron-sulfur minerals as key platforms for molecular synthesis and supramolecular organization in prebiotic environments. However, defects have been traditionally considered at the center of such assemblies, thereby underestimating the contributions of regular and pristine interfaces. Here, we combine scanning tunneling microscopy and spectroscopy (STM/STS) with density functional theory (DFT) to investigate the fundamental prebiotic chemistry system of L-Cysteine (L-Cys) on defectless FeS$_2$(100) terraces. To do so, we first achieved atomically ordered, defect-free terraces that act as support of two distinct supramolecular phases of L-Cys: one compact, highly ordered supramolecular network and another less packed, labile supramolecular network. We unveil trimer-based intermolecular interactions to be at the origin of these pattern formations. These results demonstrate that L-Cys self-assemblies can be hosted on flawless FeS$_2$ terraces due to the cooperative interplay between substrate electronic structure and intermolecular interactions, without the participation of dominant defects. Therefore, the autocatalytic activity of pyrite could have triggered the on-surface polymerization process of these non-static self-assembled structures under
primordial conditions, thereby endorsing Wächtershäuser's postulates on the origin of life.
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All authors Adriana E. Candia, Sindy J. Rodríguez, Vanina G. Franco, Mario C. G. Passeggi, Jorge Lobo-Checa, Myriam H. Aguirre
Mathematical Physics
Minkowskian open/closed conformal field theory possibly without vacuum: the Cardy case
Bin Gui
For any conformal net, not necessarily rational, we construct the associated Cardy-type conformal field theory on the Minkowski spacetimes $(\mathbb R/2\pi\mathbb Z)\times\mathbb R$ for closed strings and $[0,\pi]\times\mathbb R$ for open strings within the framework of algebraic
quantum field theory. In addition to verifying some of their basic properties, we prove three forms of Haag duality for multi-double-cones and boundary intervals, interpreted respectively as the Minkowskian versions of modular invariance, the Cardy consistency condition, and the Morita equivalence of boundary field
algebras.
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Materials Science
Role of polarity in the growth of cubic GaN within silicon inverted pyramids
David Lister, Melissa Radford, Sara Fortin et al. (+4 more)
A lack of spontaneous internal polarization makes cubic GaN (c-GaN) a well-suited material for emerging micro-LED-based short-range communication, where c-GaN promises increased speed over conventional hexagonal GaN (h-GaN). Although c-GaN is metastable, there are well-established methods for growing it in Si V- or U-grooves; the logical step is to truncate these grooves to wedges or inverted pyramids for small devices. There are limited reports of GaN grown in inverted pyramid templates, and the results are contradictory. To study this process, we perform selective area growth of GaN using organometallic vapor phase epitaxy (OMVPE) on Si inverted pyramidal templates and analyze our samples by cross-sectional TEM. We find that polarity is critical to understanding the growth of c-GaN in this four-fold geometry, in contrast to the growth in long grooves. This effect fits within the broader set of challenges of polar-on-nonpolar heteroepitaxy; the c-GaN inside the four-fold symmetric template has its
symmetry reduced by polarity to be two-fold. In typical growth conditions – where the underlying h-GaN polarity is uniform – we find this implies that two h-GaN to c-GaN grain boundaries will have a polarity inversion. We observe two different structures at these inverting boundaries, including a previously unreported inversion domain boundary along the basal plane of the undoped h-GaN. These findings show that for small devices – such as micro-LEDs – the polarity-inverting interfaces must be prevented, for example by suppressing the growth of h-GaN on two facets of the template or by locally controlling the h-GaN polarity.
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All authors David Lister, Melissa Radford, Sara Fortin, Bilal Janjua, Mohsen Asad, Karen Kavanagh, Simon Watkins
Other Condensed Matter
An Interaction Language Model: Mechanism Discovery from Statistical Patterns of Physical Interactions
Triparna Ganguly, Hanqi Jiang, Xinliang Li et al. (+5 more)
Interactions among building blocks in physical, chemical, and biological systems follow structured patterns interpretable as a learnable
language: just as
language models learn which words tend to follow others, one can learn which physical phenomena follow others and under what conditions. We introduce an Interaction
Language Model (ILM): a framework that treats interaction as a statistically structured, learnable
language for design-to-function
reasoning across fields. By learning statistical dependencies and ordering among components, ILMs infer interaction pathways, identify missing steps, and predict the next likely interaction. We demonstrate it through two complementary components, PhenoLink and PhenoSeq, applied to molecular
diffusion, a ubiquitous mechanism for energy and particle transport. PhenoLink is a directed graph of interactions among
diffusion-based events extracted from publications, where each edge aggregates paragraph-level evidence and carries a transition probability interpreted as an information cost. PhenoSeq complements this with a sequence model that proposes missing mechanistic steps under endpoint constraints. Together they form a generate-then-verify pipeline returning every explanation with a reproducible, per-step, corpus-grounded audit trail. Across four held-out suites of 172 queries, the pipeline matches a zero-shot Claude Opus 4.7 baseline on in-distribution accuracy, yet unlike the baseline, which fabricates a chain for every impossible query, it refuses up to 93.5% of transitions in corpus evidence by construction. ILM thus delivers what zero-shot generation structurally cannot: deterministic refusal of evidence-absent queries and auditable, per-step support. The framework extends to natural and engineered systems where function emerges from sequential and conditional interactions among molecules,
cells, devices, or other components.
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All authors Triparna Ganguly, Hanqi Jiang, Xinliang Li, Yi Pan, Junhao Chen, Miyuki Karunathilaka, Tianming Liu, Yohannes Abate
Atmospheric and Oceanic Physics
Conditional Tropical Cyclogenesis Rates via Rare-Event Sampling in a Neural Weather Emulator
John S. Schreck, William Chapman, Charlie Becker et al. (+1 more)
We couple Forward Flux Sampling (FFS), a non-
equilibrium rare-event technique from statistical mechanics, to a neural weather emulator (SDL-WXFormer, 1{\deg} grid spacing) to estimate conditional tropical cyclogenesis rates, or how often a tropical cyclone achieves a hurricane-level central pressure, without modifying model dynamics. Tropical cyclogenesis rates vary by orders of magnitude across regimes, yet direct ensemble sampling cannot resolve this variability at operationally feasible ensemble sizes. FFS decomposes the rare disturbance to mature cyclone intensification path into a flux through an initial interface pressure and a product of conditional crossing probabilities across four intermediate interface pressures. We use the 1{\deg} emulator because FFS requires O(10^4) model trajectories per initial condition, and because the model's calibrated
stochastic layers provide the necessary exploratory spread. Applied to 98 Atlantic basin initial conditions spanning 21 August - 8 October 2022, FFS resolves genesis rates spanning nearly three orders of magnitude, capturing a seasonal cycle qualitatively consistent with observations. A self-consistency check comparing FFS rates to independent direct-sampling rates yields a mean ratio of 1.03 +/- 0.15 across all initial conditions. Computational enhancement factors range from 3X (most active environment) to 140X (most suppressed), with a
geometric mean of 14X. Three case studies illustrate the physical diagnostics the method provides: the rate-limiting step is initial tropical organization for the Earl environment, uniformly high crossing probabilities for the Fiona precursor environment, and a compound barrier at the final intensification stages for the Ian environment. More efficient emulators would enable application of FFS to finer resolutions.
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All authors John S. Schreck, William Chapman, Charlie Becker, David John Gagne II
Mesoscale and Nanoscale Physics
Topological random alloy
Subrata Pachhal, Aziz Hasan and Adhip Agarwala
Topological phases of matter are often realized in crystalline materials. To extend their understanding beyond perfect stoichiometry, we introduce a minimal model of a topological random binary
alloy and show that the system realizes an exotic form of
impurity-band engineering. We reveal that, in contrast to Wannier charge centers pinned by
impurities in conventional
semiconductors, doping a proximate
quantum anomalous
Hall insulator results in dopant-centric
chiral current loops. The nature of such current loops is intrinsically tied to the properties of both the host and the dopant. We demonstrate that, even at dilute dopant density, these current loops can form topological domains in an otherwise trivial host and trigger a topological phase transition. On the other hand, doping a topological host having chirality opposite to that of the dopants can unexpectedly stabilize a metallic phase in which bulk transport is mediated by inter-domain edge modes.
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Optics
A Unified Perspective on Causality and One-Sided System Responses in Time and Space Across Physical and Fourier Domains
Mohammadreza Salehi and Francesco Monticone
The principle of causality has long been mathematically associated with the frameworks of Titchmarsh's
theorem and the Kramers–Kronig relations. While these relations arise naturally in the context of temporal system responses – ensuring that the effect of an applied field or force does not precede its cause – they have recently been shown to provide a pathway for realizing one-sided system responses in a variety of physical settings. In particular, one-sided frequency responses and one-sided wavevector responses have been successfully studied and engineered, enabling the prospect of numerous applications based on the complete suppression of backward scattering. In this work, we present a brief review of causality and its connection to these
Fourier-domain analogs. We then turn our
attention to the only remaining setting in which a one-sided system response may be explored: one-sided spatial nonlocality. We specifically investigate the possibility of realizing a one-sided spatial response within the widely used framework of nonlocal flat optics, where we uncover fundamental obstacles that hinder the achievement of such functionality in these structures. This, in turn, raises an intriguing open question: is one-sided spatial nonlocal response merely incompatible with the specific platform of nonlocal flat optics, or is it fundamentally forbidden by nature itself?
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Optics
Spectral DiffuserScope: a compact snapshot hyperspectral microscope
Neerja Aggarwal, Eric Markley, Kyung Chul Lee et al. (+12 more)
Hyperspectral fluorescence microscopy enables important biological and clinical applications, but conventional systems are bulky or require scanning, limiting temporal resolution and throughput. We introduce a computational snapshot hyperspectral microscope that uses compressed sensing to achieve higher spatial-spectral resolution than traditional snapshot systems. Our device is compact (~15 cm x 6 cm x 6 cm) and easily attaches to standard fluorescence microscopes. We
benchmark our system against existing snapshot methods through simulations to evaluate its spatial and spectral performance. Experimental imaging of fluorescent beads, labeled
cells, and lanthanide hydrogel beads demonstrates a practical, high-throughput solution for hyperspectral microscopy in biological and clinical applications.
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All authors Neerja Aggarwal, Eric Markley, Kyung Chul Lee, Seung Ah Lee, Junghyun Bae, Nakkyu Baek, Wook Park, Min Sung Cho, Youngbin Lim, Polly Fordyce, Stephanie Eberly, Lydia L. Sohn, William D. Houck, Kristina Monakhova, Laura Waller
Soft Condensed Matter
Rheological and Photoelastic Response of Hydrated Soft Granular Particles
Brandon Hayes, Krishnaroop Chaudhuri, Rylan Hodgson et al. (+6 more)
Photoelasticity is a qualitative and quantitative optical technique to image internal stress distributions in transparent materials. In the past few decades, discrete photoelastic particles have been used as a proxy for dry granular materials in both static, quasistatic, and dynamic analogue experiments. The technique allows the visualization of force chains, determination of the location and magnitude of contact forces, and outputs a stress tensor for each particle with shear and normal stress components. To date, little to no work has investigated photoelastic suspensions, where photoelastic granular particles are immersed in a fluid medium, despite its relevance in industrial and natural applications. The introduction of a fluid phase yields additional considerations in the rheological and photoelastic behavior of our proxy particles. In this manuscript, we summarize the state-of-the-art in resolving forces in immersed photoelastic granular materials. We introduce characterization techniques to probe changes in rheological and optical properties of hydrated photoelastic particles, and we report considerations for use of photoelastic particles in immersion-based experiments. We intend for this work to provide the leading framework to study the hydrodynamic interactions in 2D systems of photoelastic particles immersed in a fluid medium.
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All authors Brandon Hayes, Krishnaroop Chaudhuri, Rylan Hodgson, Benjamin McMillan, Ruby Gans, Hale Burke, Stephanie McNamara, Thomas Chalklen, Nathalie M. Vriend
Materials Science
Family of (NxH)-polytypes with La2WO6-related stoichiometry
E. Pospíšilová, M. Mihalkovič, N. Beronská et al. (+1 more)
Structure and chemical composition of non-stoichiometric $\mathrm{(N \times H)}$-polytypes, $\mathrm{N} \in \{3,\,4,\,5,\,6,\,7\}$, belonging to the family of La2WO6-related tungstates, are presented and the basic rules behind their construction are formulated. The polytypes are validated from the point of view of the internal energy per atom against all the competing La-O-W compounds by means of the ternary convex hull computed by DFT. According to DFT, the ground state of the La2WO6 family surprisingly turned out to be the as-yet hypothetical tungstate La2WO6.oP36, isostructural with the known compound Gd2WO6, closely related to the basic building H-block of the polytypes. One more candidate for an experimentally accessible low-energy structure, La2WO6.mC72, derived from the already observed Sm2MoO6, has been identified to lie only $\Delta E \approx 5\:\mathrm{meV/at.} \cong 60\:\mathrm{K}$ above the convex envelope.
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All authors E. Pospíšilová, M. Mihalkovič, N. Beronská, M. Gebura
High Energy Physics (Phenomenology)
Phenomenology of Long-Lived Dark Photons and Axion-Like Particles in a Mixed Portal Framework
Caglar Zorbilmez, Beyhan Tatar and Azmi Ali Altintas
We investigate the phenomenology of a dark
photon \(A'\) and an
axion-like particle (ALP) ,\(a\), connected through a mixed portal framework which simultaneously allows the conventional visible decay $(A'\rightarrow f\bar f)$ and the exotic cascade process $(A'\rightarrow a\gamma\rightarrow3\gamma)$. We derive the relevant decay widths, branching ratios, and Lorentz-boosted decay lengths, and introduce a dominance parameter \(D=\Gamma(A'\to a\gamma)/\Gamma_{\rm SM}\) to distinguish Standard Model-dominated and cascade-dominated regions, with the transition occurring at $(D=1)$. A detailed analysis of both light $(0.1\leq m_{A'}\leq10~{\rm GeV})$ and heavy $(10\leq m_{A'}\leq100~{\rm GeV})$ dark-
photon scenarios shows that the exotic channel can substantially modify the expected dark-
photon signatures, transforming otherwise long-lived or detector-stable states into experimentally accessible displaced multi-
photon events. In addition, the ALP sector itself may exhibit long-lived particle behavior, leading to distinct displaced diphoton signatures. Our results show that mixed dark-
photon-ALP portals offer a rich LLP phenomenology that can be explored at future high-luminosity
lepton colliders such as the FCC-ee.
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Fluid Dynamics
Dripping-onto-droplet rheometry of sodium alginate solutions
Nada Nazzal, Martin Drahé, Ricardo El Khoury et al. (+7 more)
In this experimental and theoretical study, we assess the extensional relaxation time of sodium alginate solutions by using dripping-onto-droplet capillary breakup rheometry (DoD), e.g., the capillary thinning and breakup of viscoelastic filaments formed following the coalescence of a millimetric-nozzle-generated pendant drop with a lower droplet cap of the same fluid contained in a millimetric pool in ambient air. Hence, we extend the analyses conducted by El Khoury et al. (2026) from Newtonian to viscoelastic fluids. Our approach relies on experiments recorded with a high-speed camera using sodium alginate in deionised water, with alginate concentrations ranging from 0.1% to 9% by weight. The results are depicted by considering the dynamics of fluid filament thinning, stress balances, and scaling laws. Extensional relaxation times are resolved from the filament diameter
evolution. Three flow regimes are highlighted: capillary-inertial, capillary-elastic, and mixed capillary-inertio-elastic. The findings are summarised in a two-dimensional diagram that correlates the filament breakup time with different flow regimes using the important dimensionless parameter of the problem, e.g., the intrinsic Deborah number (which relates the extensional relaxation time to the characteristic capillary-inertial time). This diagram can be used to quantify both the solution's extensional relaxation time and the
liquid/air surface tension solely from filament breakup times.
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All authors Nada Nazzal, Martin Drahé, Ricardo El Khoury, Irineu Lopes Palhares Junior, Cassio Oishi, Roney Leon Thompson, Loren Jørgensen, Cécile Monteux, Edith Peuvrel-Disdier, Anselmo Pereira
Mesoscale and Nanoscale Physics
Quantum sensing of nanoscale electronic phase segregation
Izidor Benedičič, J. Paul Attfield and Denis Arčon
Doping of transition metal
oxides such as CaFe$_3$O$_5$ offers a controlled way to tune the interplay of charge,
spin, and
lattice degrees of freedom, yet local-probe studies remain difficult because strong correlations and dynamic charge-
spin fluctuations obscure fine spectroscopic features in powder samples. Here, we employ
quantum magnetometry based on nitrogen-vacancy (NV) centers in nanodiamonds impressed into an Mn-doped CaFe$_3$O$_5$ powder pellet to probe static and dynamic
magnetic fields at the nanoscale across the weak
ferromagnetic transition. The splitting and broadening of the optically detected
magnetic resonance (ODMR) spectra exhibit an order-parameter-like increase by ~ 15 MHz upon cooling below the critical temperature, T$_{\rm c}$. Concomitantly, the
spin-
lattice relaxation rate, 1/T$_1$, exhibits a pronounced, divergence-like enhancement at T$_{\rm c}$, increasing by about one order of magnitude from its high-temperature value. Moreover, detailed lineshape fits of ODMR spectra together with the stretched-exponential NV magnetization recovery curves corroborate the proposed electronic phase segregation in charge-ordered and charge-averaged phases at the nanometric scales. The presented study demonstrates the viability of using nanodiamonds as a platform for nanoscale
magnetic probing of strongly correlated matter, including phenomena such as electronic phase separation.
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Cosmology and Nongalactic Astrophysics
Cosmological Concordance in an Especially Opaque Universe: A Tentative Cosmological Detection of Physical Neutrino Mass in $\Lambda$CDM
James M. Sullivan, Roger de Belsunce and Mikhail M. Ivanov
The measurement of the sum of
neutrino masses is among the primary promises of precision cosmology, achievable by combining complementary early- and late-Universe probes. However, these
datasets currently exhibit mild-to-strong disagreements within $\Lambda$CDM and its simplest extensions, giving rise to multiple tensions, including the Hubble tension, the preference for "negative"
neutrino mass, and indications of evolving dark energy. It has recently been shown that these tensions can be alleviated by adopting a higher value of the optical depth to reionization parameter, $\tau$, when large-scale
cosmic microwave background (CMB) polarization data are ignored. We extend this proposal and show that an especially high prior on $\tau = 0.11 \pm 0.006$ simultaneously addresses all three of these tensions, significantly reducing the need for new physics beyond $\Lambda$CDM. We determine the "concordance" value of $\tau$ by requiring physical
neutrino mass and consistency of the Hubble constant, $H_0$, inferred from the CMB and that preferred by the Dark Energy Spectroscopic Instrument (DESI)
baryon acoustic oscillation (BAO) and full-shape measurements. Within this high-$\tau$ Universe, we obtain the first $2\sigma$ detection of a positive
neutrino mass, $\Sigma m_{\nu} = 0.10^{+0.04}_{-0.05}$~eV at 68% C.L., while restoring cosmological concordance between
datasets within $\Lambda$CDM. In particular, low-
redshift distance predictions are consistent with DESI BAO observations and the inferred dark-energy equation-of-state parameters are consistent with a cosmological constant, both with and without
supernovae data. The concordance power of our $\tau$ prior further motivates new measurements of $\tau$, e.g., through large angular scale CMB polarization observations with the LiteBIRD, CLASS, or proposed PICO experiments. (Abridged)
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Materials Science
Bridging electrode preparation and electrocatalyst performance with physics-based causal AI
Evelyna Wang, Linda Hung, Sam Witty et al. (+2 more)
State-of-the-art artificial intelligence (AI) and Machine-Learning (ML) tools have not yet enabled rapid design of next-generation materials. Detailed physical understanding of how material properties affect device performance is required to advance materials development. For example, optimization of ink parameters for electrocatalysts has no known physical mathematical model and thus insights are difficult to translate from material studies to device studies. Herein, we demonstrate how to use the emerging AI tool, physics-based structural causal models (SCMs), to extract quantitative causative insights from complex heterogeneous electrochemical systems with small (n < 10), but multi-modal
datasets (modes > 10). Our SCM quantitatively separates the role that varying the support-to-catalyst ratios and total material loadings plays on catalytic performance. The proof of concept model developed in this work enables root-cause-analysis on the cyclic voltammograms of manganese-antimony
oxide oxygen reduction electrocatalysts on Vulcan carbon supports tested in alkaline media using a rotating disc electrode device configuration. Our preliminary causal analyses quantitatively disentangle how the catalyst performance is affected by the number of active sites versus the thickness of the electrode. To the best of our knowledge, this is the first demonstration of physics-based SCMs applied to electrochemical materials and their performance.
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All authors Evelyna Wang, Linda Hung, Sam Witty, Michaela Burke Stevens, Kevin Tran
Instrumentation and Methods for Astrophysics
SAOImageDS9: An Essential Tool for Astronomical Exploration
Antonella Fruscione, Kenny Glotfelty, William Joye et al. (+1 more)
SAOImageDS9 (DS9) is an open-source, cross-platform application for the visualization and analysis of astronomical data. Developed at the Smithsonian Astrophysical Observatory, DS9 evolved from an example implementation of reusable imaging components into one of the most widely used astronomical display environments. It has remained useful because it supports many astronomical file formats and coordinate systems, can work directly with event data and image cubes, provides interactive region-based analysis, and can communicate with external tools through command-line and messaging interfaces. DS9 is used in research, mission operations, and education across a range of wavelengths and at both ground- and space-based observatories. This paper summarizes the historical development of DS9, its principal capabilities, and its impact on the astronomical community, and concludes with an appendix describing the internal architecture that has supported its long-term sustainability.
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All authors Antonella Fruscione, Kenny Glotfelty, William Joye, Jonathan McDowell
High Energy Physics (Theory)
An asymptotic bootstrap method and its applications to Hermitian matrix models
David Berenstein and Paula Garcia Martinez
We propose an asymptotic bootstrap method to evaluate moment integrals that arise in problems related to hermitian
matrix models. These are normalized integrals of the form $a_n=\int^{\infty}_{-\infty} x^n \exp(-V(x)) dx$ where $V(x)$ is a
polynomial of $x$. The method is applicable even when the coupling constants in $V(x)= x^{2\ell}/(2\ell) + g_{2\ell-2} x^{2\ell-2}/(2\ell-2) + \dots$ are complex. We prove that the method converges asymptotically exponentially fast on a cone region determined by the first subleading coupling $g_{2\ell-2}$, which must have a positive real part and an absolute value of the argument less than $\pi/{\ell}$. We use our method to study the phase structure of Hermitian
matrix models by constructing the orthogonal
polynomials associated to these measures.
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High Energy Astrophysical Phenomena
Energy-Resolved Limits on Orbital X-ray Polarization Modulation in Cygnus X-1
Sohee Chun, Bert Vander Meulen, Kun Hu et al. (+1 more)
Reflection off the companion
star and its focused
stellar wind is predicted to modulate the X-ray polarization of black hole X-ray binaries at half the orbital period ($P_{\rm orb}/2$), with an energy-dependent amplitude. We test this prediction against all publicly available IXPE observations of Cygnus X-1, comprising 26 time bins of up to one day from 12 observation IDs spanning 2022-2024. Since the normalized Stokes parameters correlate linearly with the spectral hardness ratio in all three energy bands (2-4, 4-6, and 6-8 keV), we employ a simultaneous harmonic regression that decouples spectral variability from orbital modulation at both $P_{\rm orb}/2$ and $P_{\rm orb}$, complemented by direct fitting of 3D Monte Carlo radiative transfer
stellar companion and wind-scattering templates. After removing the spectral hardness trend, neither approach reveals statistically significant orbital modulation: permutation tests yield $p > 0.01$ in all bands, with 99% confidence upper limits of 0.25%, 0.63%, and 1.96% on the $P_{\rm orb}$ amplitude and 0.42%, 0.97%, and 2.78% on the $P_{\rm orb}/2$ amplitude in the 2-4 keV, 4-6 keV, and 6-8 keV bands, respectively. The best-fit
stellar companion and wind-scattering amplitude scaling factors in the three bands of $A = 0.67 \pm 0.85$, $0.97 \pm 0.62$, and $-1.06 \pm 1.11$ are consistent with a null result. These non-detections are sensitivity-limited, as the predicted
stellar companion and wind-scattering RMS amplitudes in the three bands of $\approx$0.10%, $\approx$0.33%, and $\approx$0.49% lie below the statistical noise floor of $\sim$0.18%, $\sim$0.38%, and $\sim$1.01%. We quantify the additional exposure required to detect the predicted signal and constrain the wind physics.
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All authors Sohee Chun, Bert Vander Meulen, Kun Hu, Henric Krawczynski
Chemical Physics
Extension of openCOSMO-RS Into a Full Open-Source Equation of State: Implementation, Parameterization, and Benchmarking
Jan Markgraf, D. G. Lisboa Girardi, Irina Smirnova et al. (+1 more)
The COSMO-SAC-Phi model developed by Soares et al. extends the COSMO-SAC activity-coefficient framework into a full equation of state by explicitly accounting for pressure effects. In this approach, pure substances and mixtures are represented as pseudo-mixtures consisting of the actual number of moles and an additional pseudo-component that describes free volume, or holes. In this work, we implement this extension within the openCOSMO-RS framework and evaluate it using a large and diverse set of molecules and binary systems. The resulting equation of state includes an extensive open-source parameter set with around 1800 pure-component entries, made freely available to the academic community. The four pure-component parameters were fitted to vapor-pressure and
liquid-molar volume data for each substance. Model performance was assessed against two
benchmark equation-of-state databases, one for pure compounds and one for binary mixtures, without introducing any binary interaction parameters. The resulting openCOSMO-RS-Phi model reproduces the accuracy of the original COSMO-SAC-Phi formulation while providing a fully open-source and accessible implementation for the scientific community. Beyond its immediate utility, it also establishes a foundation for future development of predictive EoS for electrolyte solutions.
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All authors Jan Markgraf, D. G. Lisboa Girardi, Irina Smirnova, Simon Müller
Optics · Cross-listed from math.OC
Optimal Design of Tubular Perfectly Conducting Objects in Electromagnetic Chirality
Tilo Arens, Roland Griesmaier, Marvin Knöller et al. (+1 more)
This work is about the shape optimization of long tubular objects in electromagnetic chirality (em-chirality). Em-chirality is a property of individual scattering objects or metamaterials describing their qualitatively different response to electromagnetic waves of opposite polarization handedness. The optimization is performed by a Newton-type iterative maximization of a regularized em-chirality measure with respect to the scatterer's shape. In this context, the differentiability of the object-to-far field operator map is analyzed rigorously, thereby extending previously known results on the domain derivative to the far field operator setting. Our optimal design
algorithm is based on the electric field integral equation, which is employed both for the evaluation of scattered fields and for the computation of the domain derivative. Our implementation is done via the boundary element method. The numerical examples presented in this work yield strongly em-
chiral scattering objects capable of exciting higher-order modes beyond the dipole regime with nonintuitive shapes that expand the known set of highly em-
chiral scattering objects.
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All authors Tilo Arens, Roland Griesmaier, Marvin Knöller, Raphael Schurr
High Energy Physics (Theory)
Spin-Induced Fractal Time-Crystal-Like Dynamics and Non-Markovian Memory in the Bateman Dual Oscillator
Partha Nandi and Giuseppe Vitiello
Can a closed
quantum system generate time-
crystal-like nonequilibrium behavior, self-similar scaling structures, and non-Markovian
memory without external driving or coupling to a macroscopic environment? We address this question within the
quantum Bateman oscillator formulated in a nonrelativistic (2 + 1)-dimensional phase-space noncommutative framework generated by
spin-induced spatial deformation. The resulting doubled
quantum dynamics is governed by a time-independent Hermitian
Hamiltonian and exhibits an underlying SU(1, 1) structure with amplified and damped collective modes. We show that these modes satisfy an exact discrete scaling covariance, leading to self-similar temporal
evolution without external driving. Upon tracing over one oscillator sector, the reduced dynamics becomes intrinsically non-Markovian and is governed by a history-dependent
memory kernel. The same scaling structure admits a
geometric representation in terms of logarithmic-spiral trajectories associated with the amplified and damped branches of the Bateman system. Because the mechanism relies on nonequilibrium reduced dynamics rather than
equilibrium expectation values of local observables, it lies outside the assumptions underlying conventional no-go
theorems for
equilibrium time
crystals. Our results identify
spin as the common physical origin of the amplified and damped Bateman dynamics, self-similar scaling periodicity, logarithmic-spiral structures, and non-Markovian
memory, also suggesting a natural extension of the mechanism to relativistic anyonic systems.
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High Energy Astrophysical Phenomena
Multipolar Magnetic-Field Inference for PSR J0740+6620 with Neural-Network-Accelerated NICER Pulse-Profile Modeling
Farhana Taiyebah, Constantinos Kalapotharakos, Greg Olmschenk et al. (+6 more)
We investigate the multipolar surface
magnetic-field structure of the high-mass millisecond
pulsar PSR J0740+6620 using the 32-bin bolometric NICER pulse profile of Dittmann et al. (2024). Building on the neural-network surrogate framework of Olmschenk et al. (2025), we model the emitting regions as open-field-line footpoints of an offset dipole plus axisymmetric quadrupole static
vacuum field, rather than as prescribed
geometric hotspots. We fix the
stellar mass, radius, observer inclination, and hotspot temperature ratio to the Dittmann et al. (2024) maximum-likelihood values and explore the resulting 11-dimensional
magnetic-field space. To make this feasible, we train convolutional neural-network surrogates on $5.12\times10^7$ synthetic bolometric light curves and use them in a parallel ensemble Markov Chain Monte Carlo calculation on 4000 CPU cores, accelerating likelihood evaluations by a factor of $\gtrsim 400$. We perform independent inferences for two calibrated temperature-weight prescriptions, Tw=1.31 and Tw=1.41, encoding the relative bolometric weight associated with the hotspot temperature difference. The posteriors, posterior-predictive light curves, and maximum-likelihood values are very similar, indicating weak sensitivity to this choice. The offset model reproduces the observed double-peaked profile and yields broad,
multimodal posteriors, reflecting both the background-dominated data and degeneracies of the multipolar parameterization. The hotspot-density map shows that pulse phases constrain the approximate azimuthal placement of the emission, while latitude, surface extent, and morphology remain weakly constrained. A restricted zero offset run is disfavored within the adopted field basis. This work extends neural-network-accelerated
magnetic-field inference to PSR J0740+6620 and motivates future energy-dependent, force-free, and joint X-ray/$\gamma$-ray extensions.
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All authors Farhana Taiyebah, Constantinos Kalapotharakos, Greg Olmschenk, Wendy F. Wallace, Soumi De, Abu Bucker Siddik, Diane Oyen, Thibault Lechien, Zorawar Wadiasingh