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All of arXiv

Tuesday 22 September

Systems and Control

Impact-Time Guidance via Normal Contraction to a Time-to-Go Isochron

Shivam Bajpai and Abhinav Sinha

We develop a contraction-based perspective on impact-time guidance that augments a baseline homing command with a timing bias. The proposed perspective treats the prescribed schedule as a moving time-to-go isochron and regulates motion normal to that set through velocity-normal lateral acceleration while the interceptor's speed remains constant. We derive a transport equation that characterizes homing-compatible time-to-go coordinates and define a predictor defect that quantifies the mismatch of approximate maps. We show that the scalar timing channel induces a coordinate-invariant rank-one metric on the normal quotient. To account for bounded lateral acceleration, we formulate a robust scalar filter and derive a necessary and sufficient condition for pointwise feasibility. We then show that terminal calibration and funnel invariance establish first interception at the prescribed time under the stated assumptions. We also develop a preterminal alignment and homing handover that avoids singular inversion as lateral timing authority vanishes near collision-course alignment. The proposed perspective accommodates analytic, numerical, and learned time-to-go maps that satisfy the required calibration and regularity conditions.
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Machine Learning

CORE-STACK+: Meta-Learning for Deep Stacked Generalization

Noor Islam S. Mohammad

Stacking heterogeneous vision backbones (CNNs, ViTs, and hybrids) is the de facto recipe for accuracy, calibration, and robustness, yet two coupled pathologies limit its returns. Prediction-space multicollinearity ill-conditions the meta-learner's Gram matrix, inflating weight variance and producing brittle solutions on a thin manifold. Calibration collapse compounds constituent miscalibration through naive linear stacking, so adding more models can hurt expected calibration error (ECE). Existing remedies, ridge regularization, greedy selection, model soups, and SWAG address at most one of these issues, and none jointly target conditioning and calibration in heterogeneous prediction pools. We introduce CORE-STACK+, a preconditioning pipeline with four components: (i) a kernelized redundancy filter that removes non-linear inter-model dependencies invisible to Pearson correlation, using Centered Kernel Alignment (CKA) [23]; (ii) a $<15$K-parameter differentiable meta-feature gate that learns per-sample attention over ensemble statistics; (iii) a spectrum-adaptive Ridge penalty $lambda^{star}=lmax(Chat)/SNR(Chat)$ derived from a Marchenko-Pastur signal-noise decomposition, eliminating nested cross-validation; and (iv) a Laplace-approximate Bayesian blender replacing inverse-RMSE heuristics. We prove a PAC-Bayes excess-risk bound that, for the first time, jointly accounts for prediction-space redundancy and meta-learner capacity. Across six benchmarks, CORE-STACK+ delivers $+1.8\%$ top-1 on ImageNet-1K, $-4.2$ mCE on ImageNet-C, $+0.9$ mIoU on ADE20K, and $+1.3$ AP on COCO, while reducing retained models by 35-57% and inference FLOPs by up to $41%$. ECE improves $2.1\times$ over deep ensembles without post hoc temperature scaling.
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Instrumentation and Methods for Astrophysics

Interference Meets Inference: Bayesian Time-Series Modeling of Radio-Frequency Interference

Jade M. Ducharme, Andrei Li, Michael J. Wilensky et al. (+1 more)

Radio-frequency interference (RFI) remains a major challenge for modern radio astronomy experiments. In this work, we cast RFI detection as a one-dimensional time-series anomaly-detection problem and develop a probabilistic mixture-model framework for separating a smoothly varying astronomical background from anomalous contamination. The model jointly describes the clean and contaminated components and assigns each time sample a posterior probability of belonging to the RFI state, rather than relying solely on binary flags. This probabilistic formulation provides a measure of classification confidence, enables uncertainty propagation into derived downstream statistics, and offers additional information for investigating ambiguous events. We apply the framework to observations from the Murchison Widefield Array collected in 2014, producing "soft" classification labels and seasonal RFI trends. We perform a parallel analysis using the Sky-Subtracted Incoherent Noise Spectra software pipeline (SSINS), which produces "hard" classification labels. Overall, the mixture model provides similar classification labels but offers a more comprehensive framework by providing a complementary probabilistic description of RFI contamination and its uncertainty.
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All authors Jade M. Ducharme, Andrei Li, Michael J. Wilensky, Adrian Liu

Dynamical Systems

Algebraically primitive Teichmüller curves in \Omega\mathcal M_g(2g-2)^{\mathrm{hyp}}

Myeongjae Lee

We give a complete classification of algebraically primitive Teichmüller curves in $\Omega\mathcal M_g(2g-2)^{\mathrm{hyp}}$ for $g\ge5$. They are precisely the curves generated by the double regular \((2g+1)\)-gon when \(2g+1\) is prime, and by the regular \(4g\)-gon when \(g\) is a power of two.
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Probability

Down-the-middle isometries for the Airy and KPZ sheets

Duncan Dauvergne and Fardin Syed

We find a new coupling between the Airy sheet $\mathcal{S}$ and the Airy line ensemble $\{ \mathcal{A}_n \}_{n \in \mathbb{N}}$, which we call the down-the-middle isometry. In this coupling, the Airy sheet is encoded by last passage values that start at $\mathcal{A}_k(0)$ for some $k \in \mathbb{N}$ and end on the top line $\mathcal{A}_1$. Using this coupling, we give a new construction of the (extended) Airy sheet as a scaling limit of Brownian last passage percolation and study coalescence of geodesics in the directed landscape. This coupling extends to discrete polymers and last passage percolation models, as well as to the KPZ line ensemble and KPZ sheet.
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General Relativity and Quantum Cosmology

Scalar halos and conical matching for finite-width vortices at a wormhole throat

Vedant Subhash

We study the static matter constraint associated with a conical deficit that varies along a string near a wormhole throat. A positive scalar-dependent factor multiplying the complete Abelian-Higgs Lagrangian couples a finite-width vortex to a canonical kink. At critical coupling, we obtain the leading longitudinally varying vortex tension. The flat-kink fluctuation operator has an even translational mode and an odd shape mode of mass $\sqrt{3}/L_\chi$. Reflection symmetry excludes the translational mode from the leading sourced response. We formulate the response with nonzero dressed-string boundary conditions at the longitudinal ends and derive a finite-range transverse halo. In the overlap $w\ll\rho\ll L_\chi$, its mixed stress satisfies $2\pi C\,\delta T^{\chi\,\rho}{}_l=\partial_l\mu_v^{(0)}$ to leading order, where $2\pi C$ is the azimuthal circumference. Together with the local weak-gravity deficit relation, this supplies the leading mixed Einstein constraint of a restricted varying cone. At fixed longitudinal position the sourced halo instead decays beyond $L_\chi$. Consequently, it cannot sustain that restricted cone throughout an outer overlap unless another source contributes the missing mixed stress. This obstruction is conditional on the response of the wormhole-supporting sector and is not a no-go result for general axisymmetric metrics. A finite-width calculation checks the linear-response crossover. We specify the perturbative domain and explain why a rotating extension requires an independent solution of Gauss's law. No complete backreacted wormhole solution or stability result is claimed.
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Cryptography and Security

Ajar: Measuring Open Privilege in Agent Defenses

Reshabh K Sharma, Linxi Jiang, Shuo Chen et al. (+1 more)

A language model agent acts through the tools it is given. The data it reads while working on a task can redirect what it does with those tools. A growing set of techniques for safe and secure agent execution therefore sits between the agent and its tools, aiming to enforce access control, information flow or isolation at that boundary. Today these techniques are evaluated on agent-security benchmarks built around indirect prompt injection. Those benchmarks judge a defense by how far it brings the number of successful attacks down while preserving the agent's utility. A defense is judged only on the agent's execution. It can score well on both metrics while holding open a transfer, a deletion or a broad read that no task needed. Ajar measures that open privilege directly using the existing benchmarks. It attaches to an agent-security benchmark that already exists and reuses the tasks, tool schemas, reference solutions and goal states that benchmark uses to grade its own runs. For each benign task it builds candidate tool calls the task does not need, so allowing one is privilege left open. These calls are presented to the defense at every point where the agent could act. We evaluate Ajar by attaching it to AgentDojo, where open privilege becomes a third axis beside the existing attack success and benign utility. We run it on five defenses: Progent, CaMeL, AC4A, Permission Assistant, and Claude Code's Auto mode. We observed that they leave widely different amounts of privilege open. Two defenses leak by almost the same amount yet differ widely in the benign tasks they finish, and one defense buys part of its tightness by refusing calls its tasks were entitled to make. This open privilege cannot be derived from the measured attack success or benign utility. The source code of Ajar is available at https://github.com/reSHARMA/Ajar.
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All authors Reshabh K Sharma, Linxi Jiang, Shuo Chen, Zhiqiang Lin

High Energy Physics (Phenomenology)

Towards Foundation Models on Hardware Accelerators for Particle Physics

Maya Benyas, Julia Gonski, Qibin Liu et al. (+5 more)

Bandwidth constraints require many particle physics experiments to make real-time decisions on custom hardware or firmware running simplified algorithms, unlike offline analysis, where latency is usually not a limiting factor. For example, for particle jet tagging at colliders, state-of-the-art performance is achieved by foundation models with hundreds of millions of parameters pre-trained with billions of jets. We use knowledge distillation to transfer what such models have learned into efficient networks towards deployment in hardware accelerators. The teacher is the OmniLearned foundation model fine-tuned on top quark jet tagging; the student is an attention-free Deep Sets network. We demonstrate three ways the student's performance improves: adding a message-passing layer to the Deep Sets architecture, training on the teacher's soft labels rather than on ground-truth labels alone, and distilling from a pretrained teacher rather than from the same architecture trained from scratch. In each case the gain is largest in the background rejection at low signal efficiency, the regime that is most relevant for a trigger.
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All authors Maya Benyas, Julia Gonski, Qibin Liu, P. Alex May, Vinicius Mikuni, Benjamin Nachman, Tanvi Wamorkar, Liangyu Wu

Quantum Physics

The logical set of Gaussian states under the stabilizer subsystem decomposition

Santiago Zamora, Kaustav Chatterjee, Ulrik Lund Andersen et al. (+4 more)

Universal quantum computation requires non-Gaussianity in continuous-variable systems and non-stabilizerness in discrete-variable systems. Yet, mapping a Gaussian state into the Gottesman-Kitaev-Preskill logical subspace can yield a logical qubit with non-stabilizer resources. To understand how the continuous-variable structure determines logical resources, we characterize the image of single-mode Gaussian states under the corresponding extraction channel, known as the stabilizer subsystem decomposition. Specifically, we derive series expressions for the logical Bloch vector and characterize the resulting reachable set, enabling an analytical treatment of the robustness of magic of the logical states. We then turn this geometric framework into a certification tool: by mapping a discrete-variable qubit witness to a continuous-variable squeezing witness, we obtain lower bounds on the squeezing of prepared states. We also show that ensembles of Gaussian states can violate both stabilizer and classical bounds. Violation of the stabilizer bound certifies the relational resource known as "set-magic," while violation of the classical bound enables the certification of cryptographic randomness at moderate squeezing.
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All authors Santiago Zamora, Kaustav Chatterjee, Ulrik Lund Andersen, Thiago Lucena de Macedo Guedes, Jonatan Bohr Brask, A. de Oliveira Junior, Rafael Chaves

High Energy Astrophysical Phenomena

A Coherent Search for New Galactic Magnetars using Fermi/GBM and follow-up Swift/BAT: 7 Candidates and a Large Burst Catalog

Ariel Perera, Barak Zackay and Tejaswi Venumadhav

Galactic magnetars are a rare class of neutron stars with extreme magnetic fields, with only about 30 known sources. Their short hard X-ray and soft gamma-ray bursts provide an important channel for discovering magnetar activity. Wide-field instruments such as the Fermi Gamma-ray Burst Monitor (GBM) are well suited to detecting these bursts, but their broad localization uncertainties make it difficult to associate individual bursts with specific sources. Coded-aperture telescopes, in contrast, provide arcminute-scale localizations but have narrower fields of view. We search for previously unidentified magnetars and construct a magnetar burst catalog by combining a broad sample of short, soft triggers from our coherent GBM detection pipeline over 2013-2025 with targeted searches of archival Swift/BAT images. We develop a statistical association framework that uses BAT detections to localize GBM bursts to arcminute precision, together with a spatio-temporal clustering framework that associates poorly localized bursts with common sources. Together, these methods identify 1720 magnetar bursts, of which 1170 are confidently associated with 11 known magnetars. The remaining 550 bursts could not be assigned to specific sources. We identify seven candidate new magnetars through three complementary discovery channels. The catalog, composed of the associated bursts, extends to the lowest fluences observed by GBM. We also provide spectral and temporal analyses of the catalog. The new candidate sources provide targets for X-ray follow-up that could reveal previously unidentified Galactic magnetars. More broadly, this work demonstrates how combining instruments with complementary capabilities can maximize the scientific return of high-energy transient observations.
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Algebraic Geometry

The non-abelian Hodge correspondence for extensions on quasi-projective curves

Quoc-Anh Tran

Let $\bar{X}$ be a smooth projective connected complex curve, $D \subset \bar X$ be a finite set of reduced points, and $X=\bar X\setminus D$. We give a moduli-theoretic construction of an exact equivalence between logarithmic flat bundles on $(\bar X, D)$ with nilpotent residues and semistable logarithmic Higgs bundles of degree zero with nilpotent residues. This extends the tame Simpson-Mochizuki correspondence on polystable bundles.
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Combinatorics

The Laplacian $S_{n,n}$ conjecture is true

Nathaniel Johnston

The "$S_{n,n}$ conjecture" asserts that there does not exist a simple graph on $n$ vertices with Laplacian spectrum $\{0,1,2,\ldots,n-1\}$ for any integer $n \geq 2$. This conjecture has already been proved when $2 \leq n \leq 15$ and when $n \geq 6,649,688,933$. We prove all remaining cases and thus establish that the conjecture is true.
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Earth and Planetary Astrophysics

JWST and HST Confirm Transit Timing Variations for the Ultra-Hot Jupiter TOI-2109 b

Michael Greklek-McKeon, Julie Inglis, Nicole L. Wallack et al. (+9 more)

Ultra-hot Jupiters are a rare yet valuable subset of exoplanets that can help elucidate both the internal properties of their host stars as well as the orbital evolution of close-in planets. An extreme among extremes, TOI-2109 b is a super-Jupiter ($1.347 \pm 0.047 R_{\rm Jup}$, $5.02 \pm 0.75 M_{\rm Jup}$) with the shortest orbital period (0.67247479 $\pm$ 0.00000028 days) and the fastest predicted orbital decay rate of any known giant planet. Previous observations hinted at a quadratic long-term trend in the transit timing variations (TTVs) consistent with orbital decay, as well as short-term sinusoidal TTVs consistent with a near-resonant planetary companion that would indicate a dynamically quiescent migration pathway. Here, we combine archival ground-based, TESS, and CHEOPS photometry with new transit and eclipse data from HST and JWST to update the TTV analysis. We find very strong evidence for sinusoidal TTVs over a linear ephemeris ($\Delta$BIC of 33.6), consistent with a nearby planetary companion as suggested by J.-V. Harre et al. 2024, and rule out several non-planetary scenarios that could explain the sinusoidal TTVs. We also find strong evidence of a quadratic TTV trend ($\Delta$BIC of 6.75) consistent with an orbital decay rate of -3.46 $\pm$ 1.17 ms/yr and a stellar tidal quality factor of 2.13$^{+1.18}_{-0.61} \times10^7$, though we cannot rule out line-of-sight acceleration as the cause of the quadratic trend. If our results are confirmed, TOI-2109 b would be the only known exoplanet besides WASP-12 b with a decaying orbit and the most extreme of an ultra-rare class of close-in giant planets with nearby companions.
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All authors Michael Greklek-McKeon, Julie Inglis, Nicole L. Wallack, Shreyas Vissapragada, Ian Wong, John R. T. Allen, Yayaati Chachan, Fei Dai, Guangwei Fu, Tiffany Kataria, Thaddeus D. Komacek, Johanna K. Teske

Cryptography and Security

ACTS: A multi-tier benchmark evaluating LLM cipher identification under controlled blind conditions

Youssef Hamdi Zafaan Ibrahim and Mohammed Khalaf Salama

We introduce ACTS (Artifacts in Cipher Testing Suite), a reproducible benchmark that isolates cryptanalytic ability through tiered metadata deprivation (Tier-1: full metadata; Tier-2: filename only; Tier-3: completely blind) and tests forced reasoning (Tier-5: chain-of-thought, code-as-reasoning, self-correction) on ciphertext alone. A 10-configuration ablation study on 7,000 files, using a single 70/30 train-test split for feature-removal analysis, provides additional evidence at scale. Live API inference on a v2b corpus with fully randomised padding (PKCS7, ISO 10126, and ANSI X9.23 selected per file), unique CSPRNG keys, and unique plaintexts (127 files per model, 381 Tier-1 records, 380 Tier-3 records across three cloud systems, supplemented by 254 autonomous agentic evaluations in Tier-4) yields a combined Tier-3 accuracy of 30.8%, only modestly above the 14.3% random baseline for seven-way classification. The corresponding combined metadata-dependency gap is 40.9 percentage points (Tier-1: 71.7% vs. Tier-3: 30.8%). Against a classical Random Forest (69.2% on 7,000 files, trained on engineered byte-level features), the observed live gap is 38.4 percentage points. Because this comparison spans different input representations and training paradigms, the gap should be interpreted as an overall capability difference rather than a clean factorial decomposition. Six findings are reported: (1) Metadata dependency remains large; (2) Scaling failure under blind conditions; (3) Forced reasoning is epiphenomenal; (4) The observed live capability gap exceeds earlier heuristic estimates; (5) The signal is primarily structural rather than statistical; (6) Heuristic invariance versus ML fragility reveals different failure modes.
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Quantum Physics

Transparent Domain Walls through Information Convex Sets

Jintae Kim, Amanda Gatto Lamas, Jacopo Gliozzi et al. (+3 more)

In $(2+1)$-dimensional topologically ordered many-body states, transparent (topologically deformable) domain walls are invisible to local topological probes, yet can modify the ground state degeneracy (GSD) and transmute anyons transported across them. Here, we develop an entanglement-bootstrap framework using information convex sets (ICSs) on local and noncontractible annuli to extract information about transparent domain walls directly from ground state wavefunctions at fixed points of Abelian topological phases on a torus, without taking categorical defect data as input. We derive fusion rules governing the action of anyons on extreme points of ICSs on noncontractible annuli and determine their quantum dimensions. Extreme points invariant under transport around the complementary cycle correspond one-to-one to minimum entropy states (MESs), and their number equals the GSD. The maximal topological entanglement entropy (TEE), $\gamma_{\rm LW}^{\max}=\log(\mathcal{D}/d_\alpha)$, probes the net effect of walls crossing the chosen annulus, where $\mathcal{D}$ is the total quantum dimension and $d_\alpha$ is the quantum dimension of an extreme point of its ICS. In contrast, the maximal entanglement asymmetry is $\Delta S_X^{\max}=\log\mathrm{GSD}$. This value is the same for both annulus orientations and reflects the combined effect of the transparent domain walls. We further show that transparent domain walls can give rise to symmetries supported jointly on the two chosen fundamental cycles that cannot be decomposed into a product of two $1$-form symmetry operators, one supported on each cycle. By relating their action on MESs to anyon tunneling and the fusion rules, we clarify how these symmetries connect distinct ground states. Additionally, we apply the framework to Wen's plaquette model, the anisotropic dipolar toric code, and the rank-2 toric code.
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All authors Jintae Kim, Amanda Gatto Lamas, Jacopo Gliozzi, Bowen Shi, Taylor L. Hughes, Jong Yeon Lee

Artificial Intelligence

Harness as a Language: A Minimalist Agent Framework With Maximal Expressivity

Zhening Li, Joshua Liu, Mateja Vukelic et al. (+7 more)

Modern language-model agents are built around the agent loop: the LLM is placed in an environment exposing a set of tools, and the LLM has full control over the workflow by alternating between tool calls and observing their output. However, certain capabilities such as long-term memory and self-improvement currently require specialized systems beyond the agent loop itself. We built an LLM agent framework, JAZ, to explore the extent to which a minimal harness that is little more than the agent loop itself can accomplish tasks these specialized systems are built for. JAZ exposes a single LLM-based primitive `invoke` and provides a set of built-in hooks that allow the programmer to apply constraints and perform monitoring. Generalizing existing code-mode agent loops, `invoke` is the simplest loop that satisfies two defining properties: (1) the LLM can write arbitrary executable code that can include recursive `invoke`; (2) everything visible to the LLM - all inputs to `invoke` as well as its interaction history with the code environment - are variables in the code environment. We motivate our design from first principles, viewing `invoke` as a language primitive representing a function whose implementation is provided at runtime by an LLM every time it is called. To validate the design of our core `invoke` primitive, we evaluate `invoke` - with only prompting, no manually designed tools, harness, or external systems (e.g., memory or the file system) - on workflows traditionally implemented through specialized harnesses. On long-horizon workflows requiring recall far beyond the context window, JAZ `invoke` outperforms Letta (MemGPT) by 8% at half its cost on the recall-heavy portion of StuLife. On continual self-improvement, JAZ `invoke` outperforms ACE by 4% at a lower cost on AppWorld.
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All authors Zhening Li, Joshua Liu, Mateja Vukelic, Nicole Shen, Supriya Lall, Amitayush Thakur, Alex Zhang, Omar Khattab, Jonathan Light, Armando Solar-Lezama

Machine Learning

PR-Smoother: Simulator-Preserving Non-Gaussian Smoothing for Data Assimilation

Yuta Tarumi

Many physical data assimilation (DA) workflows require smoothing methods that represent non-Gaussian posteriors over physical state variables, scale to high-dimensional simulators, train from observation windows alone, and remain compatible with calibration of the prescribed simulator. We introduce PR-Smoother, a simulator-preserving amortized smoother designed for this prescribed-simulator DA regime. Its key design principle is to keep the prescribed simulator explicit in both the evidence lower bound and the variational family: rather than learning replacement dynamics or a learned trajectory prior, PR-Smoother learns only future-conditioned corrections around the prescribed rollout. This yields an explicit non-Gaussian smoothing distribution over physical trajectories and supports joint state, parameter, and sensor-bias learning from observations alone. The variational family contains the exact smoother in deterministic and linear-Gaussian limits. Empirically, PR-Smoother captures multimodal posteriors in 4-dimensional Lorenz-96, remains accurate under ambiguous nonlinear observations and process noise in 40-dimensional Lorenz-96, and scales to joint state-parameter-bias inference in 16,384-dimensional Kolmogorov flow.
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Quantum Physics

Deterministic photon waveform adaptation for quantum connectivity

Jeffrey Mohan, Jérémy Berroir, Filippo Borselli et al. (+9 more)

The scalability of quantum technologies will depend on the ability to interconnect independent quantum systems through photonic channels. However, heterogeneous quantum platforms emit and absorb photons with widely differing properties, severely limiting inter-node interference and modular connectivity. Here we demonstrate a cold-atom optical quantum memory that simultaneously achieves near-unity storage-and-retrieval efficiency and deterministic temporal adaptation of single photons between arbitrary and programmable input and output pulse waveforms. Operating at high optical depth and within a fully integrated architecture, the system can store photons with durations spanning over three orders of magnitude and reshape them arbitrarily without compromising efficiency, achieving compatibility with many current platforms. By augmenting the role of a quantum memory from a passive storage element to an active programmable photonic interface, our results establish a key building block for scalable entanglement-based quantum networks and modular quantum computing architectures.
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All authors Jeffrey Mohan, Jérémy Berroir, Filippo Borselli, David Libault, Ferhat Loubar, Kilian Müller, Jed Rowland, Félix Hoffet, Eleni Diamanti, Tom Darras, Tommaso Mazzoni, Julien Laurat

High Energy Physics (Phenomenology)

The universe as a superconductor: How to search for a photon mass

Andrei Gruzinov, Anson Hook and Junwu Huang

We revisit the bounds on the photon mass when it arises from an Abelian Higgs mechanism rather than a Proca term. Because the higgs is necessarily millicharged and light, the phase of the theory (Meissner, vortex, or symmetry-restored) depends on the ambient magnetic field, so the photon mass an experiment measures depends on the environment it is performed in. We classify existing experiments by the phases in which they apply, in analogy with Type I and Type II superconductors. For Type I photon masses, magnetic fields in galaxies and the intergalactic medium can restore the symmetry everywhere, allowing a vacuum photon mass as large as $0.3 \,{\rm MeV}$. Regions of photon mass as large as $10^{-5}\, {\rm eV}$ could be present in the Universe, and measurement of frequency dependent optical depth can potentially reveal these regions. For Type II photon masses, we show that the strongest constraints mainly arise from the requirement that the galactic dynamo generates the observed magnetic fields, which we derive by generalizing magnetohydrodynamics to a nonzero photon mass. Since the terrestrial magnetic field restores the symmetry in much of the remaining parameter space, laboratory searches performed inside large magnetically shielded volumes, or in space, could probe photon masses invisible to any experiment on Earth. Measurements of distant light sources, in particular, fast radio bursts, also offer unique sensitivity to parameters invisible to lab experiments.
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Astrophysics of Galaxies

Galaxies Below the Fundamental Metallicity Relation Are Morphologically Disturbed: Merian H$\alpha$ Morphologies and DESI Metallicities

Abby Mintz, Jenny E. Greene, Shany Danieli et al. (+8 more)

Empirical results have revealed a connection between a galaxy's metallicity, mass, and star formation rate, known as the fundamental metallicity relation (FMR), in which metallicity increases with stellar mass and decreases with SFR. Physical interpretations of the FMR suggest that actively star-forming galaxies are fueled by pristine gas, likely obtained via IGM accretion or minor mergers. Here we demonstrate the value of galaxy morphology as an additional axis in the FMR. Using medium-band imaging from the Merian Survey, we construct spatially resolved maps of stellar continuum and H$\alpha$ emission for a large sample of galaxies with DESI DR1 spectra, reaching stellar masses down to $10^8$ M$_\odot$. We measure non-parametric morphological parameters from the emission maps and derive gas-phase oxygen abundances from the spectra using strong-line calibrations. We fit a series of simple linear models to explore correlations among the metallicity, stellar mass, sSFR, and morphological parameters. We find that galaxies that are more metal-poor than predicted by the FMR appear particularly disturbed. At fixed stellar mass and sSFR, metallicity is inversely correlated with the asymmetry of both the continuum and H$\alpha$ morphology. The observed trends – and the existence of particularly metal-poor, morphologically disturbed, highly star-forming galaxies – are consistent with external burst triggering. Our results indicate that a galaxy's morphology is linked to its metallicity and star formation history, providing an additional observational probe of the physical drivers of elevated star-formation in low-mass galaxies.
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All authors Abby Mintz, Jenny E. Greene, Shany Danieli, Erin Kado-Fong, Alexie Leauthaud, Jiaxuan Li, Yifei Luo, Annika H. G. Peter, Joy Bhattacharyya, Mingyu Li, Akaxia Cruz

High Energy Physics (Phenomenology)

Benchmark Dark SMEFT Scenarios from the Interplay of Flavor Physics and Dark Matter Searches

Lipika Kolay, Soumitra Nandi and Ipsita Ray

We investigate the interplay between low-energy flavor physics and dark matter (DM) phenomenology within the dimension-6 dark Standard Model Effective Field Theory (dSMEFT), featuring a fermionic DM candidate. Focusing on a minimal set of effective operators, we analyze both single- and multi-operator scenarios under current flavor and DM constraints. We show that correlated multi-operator configurations are required to simultaneously satisfy all existing bounds, leading to tightly constrained benchmark regions with implications for future collider searches. We further present representative phenomenological predictions and discuss possible ultraviolet completions of the effective framework.
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Quantum Physics

Sustained growth of quantum circuit complexity in many-body Hamiltonian dynamics

Wonjun Lee, Saúl Pilatowsky-Cameo and Soonwon Choi

The quantum circuit complexity of an evolving many-body quantum system is believed to exhibit a sustained growth, maintained for timescales much longer than the onset of thermalization. Most previous works have focused on models which violate energy conservation, such as random unitary circuits. Here we study generic, local time-independent Hamiltonian dynamics. We unconditionally prove that for generic local Hamiltonians and typical initial product states at high effective temperature, the robust quantum circuit complexity must grow over a very long period of time, attaining an exponentially large value at late times. Our approach relies on two structural properties that we prove rigorously: (i) generic local Hamiltonians satisfy generalized spectral no-resonance conditions of arbitrary order, and (ii) typical high-temperature product states are effectively supported in exponentially many energy eigenstates. These properties have been widely assumed without proof in prior works. As corollaries of this result, we show the late-time state displays robust volume-law entanglement that is irremovable by polynomial-size circuits, and we establish a no fast-forwarding result for generic local Hamiltonians. We also lower bound the complexity of preparing sufficiently large subsystems with local quantum channels, in contrast with sufficiently small thermalizing regions which we show retain low complexity at late times.
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Astrophysics of Galaxies

DIISC-VII: Linking Radial Gas Motions to Anomalously Low Metallicity Star-forming Regions in the XUV Disk of NGC 3344

Alejandro J. Olvera, Sanchayeeta Borthakur, Enrico M. Di Teodoro et al. (+4 more)

We present evidence connecting anomalously low-metallicity regions to radial gas inflows in the extended ultraviolet (XUV) disk of the galaxy NGC 3344. Anomalously low-metallicity H II regions are hypothesized to result from the accretion of metal-poor gas, but a direct link between gas flows and low metallicity gas has not been previously established. We use high-resolution H I-21cm imaging from the Very Large Array to trace neutral gas kinematics and multi-slit optical spectroscopy from the MMT to trace the gas-phase metallicity of 76 H II regions in NGC 3344. The galaxy exhibits a negative radial metallicity gradient of $-0.378$ dex $\mathrm{R}_{25}^{-1}$, with H II regions in the XUV disk showing nearly twice the metallicity scatter of those in the inner disk and several showing an anomalously low metallicity. Modeling the H I disk as tilted rings with 3DBarolo, we find gas moving radially inwards within the XUV disk at an average radial velocity of 6 $\mathrm{km\ s^{-1}}$, likely fueling star formation and diluting the metallicity, thereby producing anomalously low metallicity regions. Chemical evolution models indicate that the gas fraction, effective yield, and mass-loading factor profiles are disrupted at the onset of the XUV disk, as expected from recent gas flows. This example is the first direct detection of how radial gas flows can support stellar disk expansion and cause inside-out galaxy growth.
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All authors Alejandro J. Olvera, Sanchayeeta Borthakur, Enrico M. Di Teodoro, Kanak Saha, Mansi Padave, Hansung B. Gim, Emmanuel Momjian

High Energy Physics (Theory)

Asymptotic limits in class-$\mathcal{S}$ theories and non-Abelian Hodge theory

Thomas W. Grimm and Amineh Mohseni

We develop a non-Abelian Hodge-theoretic refinement of asymptotic limits in type-$A$ class-$\mathcal S$ theories, enriching the geometric description of the degenerating UV curve with gauge-theoretic data encoded by the associated Hitchin system. A degeneration of the UV curve produces a long plumbing tube, which we equip with the local monodromy data of a Hitchin-Simpson flat connection admitting a regular-singular logarithmic model. The semisimple and unipotent parts of the monodromy govern, respectively, the power-law and logarithmic growth of flat sections through the tube. Combining this non-Abelian holonomy with the geometric Picard-Lefschetz monodromy yields a decorated cusp label that incorporates Higgs-bundle information and extends tube-wise to intersections of boundary divisors. We also discuss a particular class of monodromy labels for which the weak gauge algebra specified by the fixture and gluing data lies in the reductive monodromy centralizer. In type $A$, we organize the local monodromy labels into discrete types specified by the eigenspace multiplicities of the semisimple part and the Jordan type of the nilpotent logarithm of the unipotent part. Finally, we illustrate the construction for $SL(3,\mathbb C)$ on the four-punctured sphere and $SL(4,\mathbb C)$ on the two-punctured torus.
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High Energy Physics (Phenomenology)

High-Temperature Vacua of the Standard Model from One-Form Symmetry

Ling-Xiao Xu

We study the high-temperature vacua of the Standard Model from the perspective of generalized symmetries and the global structure of the gauge group. We analyze the one-loop effective potential for Polyakov loop holonomies, incorporating the gauge identifications induced by gauging discrete subgroups of the electric one-form symmetry. This provides a classification of physically inequivalent vacua for each gauge-group quotient. We further comment on the effects of additional center-charged matter on the residual one-form symmetry and the vacuum structure.
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Strongly Correlated Electrons

Fermion bag study of the two-dimensional Majorana-Hubbard model at finite hopping

Mark Johnston and Emilie Huffman

The two-dimensional Majorana-Hubbard model on the $\pi$-flux lattice involves the most local interaction possible for a lattice with one relativistic Majorana fermion per site. It is predicted to host a Majorana semimetal, dimerized phases, and quantum-critical points with an emergent $U(1)$ symmetry. Nonperturbative lattice calculations for this model remain a major open challenge, thus far limited to zero hopping. We present quantum Monte Carlo simulations of the model at finite hopping using Hamiltonian fermion bags, which are based on a continuous-time expansion with Boltzmann weights that are Pfaffians of a matrix with dimension set by the expansion order, and which give the sign of the weight. Sign problem severity is related to the location of zero modes in the free hopping matrix, and for couplings $g\lesssim 0.7$ and $\beta=L/4$ it is fully removed for lattices up to at least $256$ sites. The interaction strength $g>0$ enhances the $U(1)$-charged dimerization doublet and suppresses the neutral channel, as the renormalization group predicts. Increasing the interactions also restores $U(1)$ symmetry in the component of the dimerization correlator that is even under bond orientation exchange, but not its odd component. There is a persistent anisotropy in the odd component with the symmetry of a lattice nematic. The data is consistent with a gapless semimetal throughout the sign-problem-minimal window.
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Quantum Physics

Bosonic Error Correction with Fluxonium

Shantanu R. Jha, Shoumik D. Chowdhury, Gabriele Rolleri et al. (+22 more)

Bosonic quantum error correction (QEC) offers a hardware-efficient route to fault-tolerant quantum computing. To date, however, superconducting circuit implementations of bosonic codes have utilized centimeter-scale 3D microwave cavities controlled by fixed-frequency transmon qubits, with logical lifetimes limited by transmon bit-flip errors. Here, we realize bosonic QEC in a fully planar architecture by pairing a heavy fluxonium, whose $451 \pm 70~\mu\mathrm{s}$ bit-flip lifetime exceeds that of any control qubit in previous demonstrations, with an on-chip Archimedean spiral resonator several orders of magnitude smaller in mode volume than prior 3D cavities. We prepare finite-energy Gottesman-Kitaev-Preskill (GKP) states and stabilize them using measurement-free error correction with rapid fluxonium reset, extending the logical lifetime by a factor of $1.59 \pm 0.05$. These results provide the first demonstration of resonator control using a weakly coupled fluxonium and, with it, the first realization of standalone bosonic QEC in a fully planar superconducting circuit architecture.
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All authors Shantanu R. Jha, Shoumik D. Chowdhury, Gabriele Rolleri, Anaida Ali, Lev-Arcady Sellem, Réouven Assouly, David Pahl, Lukas Pahl, Junyoung An, Farid Hassani, Hung-Yu Tsao, Chia-Chin Tsai, Aranya Goswami, Gabriel D. Cutter, Jeremie Boudreault, Jeffrey M. Gertler, Michael A. Gingras, Bethany M. Niedzielski, Jeffrey M. Knecht, Mollie E. Schwartz, Kyle Serniak, Jeffrey A. Grover, Baptiste Royer, Max Hays, William D. Oliver

Instrumentation and Methods for Astrophysics

EPIMETHEUS: Effective point spread function inferred from mosaics

Pietro Benotto, Benedetta Vulcani and Vittoria Altomonte

Accurate knowledge of the point spread function (PSF) is essential for a wide range of astronomical applications, from astrometry to precision photometry. However, deriving a robust average effective PSF (ePSF) from astronomical mosaics is particularly challenging due to the superposition of exposures taken at different epochs, under different observing conditions, and with varying position angles (PAs). To address this issue, we present EPIMETHEUS, an open-source Python library designed to manage the entire ePSF construction workflow, from initial star selection to final model generation. Built with a modular architecture, EPIMETHEUS avoids black-box methodologies, ensuring full transparency and giving the user complete control over the stellar sample to use for the ePSF building to meet specific scientific requirements. The software can process multiple images or mosaics simultaneously to retrieve the ePSF, a crucial feature when individual fields lack a sufficient number of bright, unsaturated stars. Candidate stars can be automatically filtered based on orientation and light concentration, with options for manually excluding stars through a semi-automatic visual inspection. Although EPIMETHEUS is specifically optimised to handle the roto-translation complexities inherent to multi-epoch mosaics, it is versatile and can be equally applied to derive ePSFs from simpler, single-orientation images where rotational corrections are not required. Finally, to demonstrate the software's capabilities and provide an immediate resource, we release empirical ePSFs for standard HST and JWST filters across the COSMOS, UDS, Abell 2744, and GOODS-S fields.
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High Energy Astrophysical Phenomena

Compact Object Mergers and Micro-Tidal Disruption Events: A Multi-Messenger Probe of Dense Stellar Environments

Konstantinos Kritos, Francesco Iacovelli, Rosalba Perna et al. (+1 more)

Dense stellar environments such as globular clusters and young massive clusters produce both compact-object mergers detectable in gravitational waves and tidal disruption events observable electromagnetically. We investigate compact-object mergers, tidal disruption events, and micro-tidal disruption events ($\mu$TDEs) in these environments using rapid Monte Carlo star-cluster simulations with the Rapster code, extended with a unified treatment of neutron-star (NS) and black-hole (BH) spin evolution under disk accretion across the NS-to-BH transition, as well as new dynamical channels for disruptions by single compact objects and by BH-BH binaries. Simulating $10^5$ clusters across ten model variations and two formation histories, we find a BH-BH merger-rate density peaking at $z\approx2$-$3$ at several tens ${\rm Gpc}^{-3}\,{\rm yr}^{-1}$, consistent with the local LVK rate, while the cumulative number of $\mu$TDEs exceeds that of mergers by a factor of a few. Since we include only dynamically formed binaries, $\approx90\%$ of $\mu$TDEs proceed through single compact-object-star encounters, and our rates are conservative lower limits. Prograde accretion during $\mu$TDEs spins up compact objects, providing a purely dynamical, randomly oriented pathway for producing high-spin BHs, and can drive accretion-induced collapse of NSs to BHs that populate the lower mass gap.
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All authors Konstantinos Kritos, Francesco Iacovelli, Rosalba Perna, Emanuele Berti

Astrophysics of Galaxies

Euclid Quick Data Release (Q1): Disc breaks highlight the structural evolution of galaxies through time

Euclid Collaboration: P. M. Sanchez-Alarcon, J. Román, S. Comeron et al. (+301 more)

Changes in the slope of the radial surface brightness profiles of disc galaxies, or disc breaks, encode valuable information about the processes driving disc formation and growth. Until now, due to the resolution and depth required, statistical studies of break types have been limited mostly to the local Universe. We aim to study the structural properties and redshift evolution of disc breaks in a large and statistically representative sample of galaxies out to redshift z=1 using the superb depth and resolution of Euclid. We develop an automatic pipeline to extract and analyse surface brightness profiles of 8748 disc galaxies selected from the Euclid Q1 dataset. The pipeline includes advanced masking, surface brightness profile extraction, integrated photometry and structural parameter measurements, and piecewise modelling to classify galaxies into Types I (pure exponential), Type II (down-bending), Type III (up-bending), and composite break (e.g., Type~II+III, Type~II+II, etc) profiles. We quantify structural parameters such as scale lengths, break radii, and surface brightness levels, and analyse their distributions and redshift dependence. Our automatic method produces reliable masks and deep surface brightness profiles, and classifies galaxy profiles with an estimated accuracy of 70%. Using a subsample of 4385 galaxies with reliable classifications, we find that the most common profiles are Types II, II+III, I, and III. We find substantial evolution in the fraction of disc breaks with time. Type II profiles dominate at low redshift (50%), while Types III and II+III profiles increase in frequency with lookback time, reaching 30% each at z~1. Our study provides the first statistically robust measurement of the evolution of disc break types over 5 Gyr. The observed trends support a scenario in which secular processes replace environmental influences as galaxies mature.
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All authors Euclid Collaboration: P. M. Sanchez-Alarcon, J. Román, S. Comeron, J. H. Knapen, M. Huertas-Company, F. Buitrago, M. Montes, A. S. Borlaff, P. M. Marcum, J. Junais, E. Duran-Camacho, M. N. Le, M. Dunn, H. Dannerbauer, B. Altieri, A. Amara, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, A. Biviano, M. Bolzonella, E. Branchini, M. Brescia, J. Brinchmann, S. Camera, G. Cañas-Herrera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, A. Costille, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, G. De Lucia, C. Dolding, H. Dole, F. Dubath, C. A. J. Duncan, X. Dupac, S. Dusini, S. Escoffier, M. Fabricius, M. Farina, R. Farinelli, S. Ferriol, F. Finelli, S. Fotopoulou, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, S. Gwyn, W. G. Hartley, S. V. H. Haugan, J. Hoar, H. Hoekstra, W. Holmes, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, A. Kiessling, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, M. Magliocchetti, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, S. Marcin, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, N. Mauri, E. Medinaceli, S. Mei, M. Melchior, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, P. Monaco, A. Mora, M. Moresco, C. Moretti, L. Moscardini, R. Nakajima, C. Neissner, S.-M. Niemi, C. Padilla, K. Paech, S. Paltani, F. Pasian, W. J. Percival, V. Pettorino, A. Pezzotta, S. Pires, G. Polenta, M. Poncet, L. A. Popa, C. Porciani, L. Pozzetti, F. Raison, A. Renzi, J. Rhodes, G. Riccio, I. Risso, E. Romelli, M. Roncarelli, R. Saglia, Z. Sakr, D. Sapone, B. Sartoris, P. Schneider, T. Schrabback, A. Secroun, G. Seidel, S. Serrano, P. Simon, C. Sirignano, G. Sirri, J. Skottfelt, L. Stanco, J. Steinwagner, P. Tallada-Crespí, A. N. Taylor, H. I. Teplitz, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, L. Valenziano, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, E. Zucca, V. Allevato, M. Ballardini, E. Bozzo, C. Burigana, R. Cabanac, M. Calabrese, A. Cappi, J. A. Escartin Vigo, J. Martín-Fleitas, S. Matthew, R. B. Metcalf, A. A. Nucita, M. Pöntinen, V. Scottez, M. Sereno, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, I. T. Andika, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, P. Bergamini, D. Bertacca, M. Bethermin, A. Blanchard, L. Blot, M. Bonici, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, F. Caro, C. S. Carvalho, T. Castro, F. Cogato, S. Conseil, T. Contini, A. R. Cooray, O. Cucciati, G. Desprez, A. Díaz-Sánchez, S. Di Domizio, J. M. Diego, P. Dimauro, P.-A. Duc, M. Y. Elkhashab, A. Enia, Y. Fang, A. Finoguenov, F. Fontanot, A. Franco, K. Ganga, J. García-Bellido, T. Gasparetto, V. Gautard, R. Gavazzi, E. Gaztanaga, F. Giacomini, F. Gianotti, G. Gozaliasl, M. Guidi, C. M. Gutierrez, A. Hall, C. Hernández-Monteagudo, H. Hildebrandt, J. Hjorth, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, J. Kim, C. C. Kirkpatrick, S. Kruk, L. Legrand, M. Lembo, F. Lepori, G. Leroy, G. F. Lesci, J. Lesgourgues, L. Leuzzi, T. I. Liaudat, A. Loureiro, J. Macias-Perez, E. A. Magnier, F. Mannucci, R. Maoli, C. J. A. P. Martins, L. Maurin, G. Morgante, K. Naidoo, P. Natoli, A. Navarro-Alsina, S. Nesseris, D. Paoletti, F. Passalacqua, K. Paterson, A. Pisani, D. Potter, S. Quai, M. Radovich, G. Rodighiero, S. Sacquegna, M. Sahlén, D. B. Sanders, E. Sarpa, A. Schneider, M. Schultheis, D. Sciotti, E. Sellentin, F. Shankar, L. C. Smith, J. G. Sorce, K. Tanidis, G. Testera, R. Teyssier, S. Tosi, A. Troja, M. Tucci, C. Valieri, A. Venhola, D. Vergani, G. Verza, P. Vielzeuf, N. A. Walton, D. Scott