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Physics

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Thursday 20 August

General Relativity and Quantum Cosmology

Spinning test particles in a weak gravitational wave and the memory effect

In this work, we investigate the worldline deviation of spinning test particles in a weak gravitational wave (GW) spacetime. Within the pole-dipole approximation and the Tulczyjew spin supplementary condition, we consider the modified deviation equation, which contains the standard geodesic deviation term and an additional contribution generated by the Mathisson-Papapetrou-Dixon (MPD) force. We demonstrate how the deviation equation can be solved under viable approximations to yield a new expression for the change in the deviation vector in terms of the perturbation $h_{ij}$, its time derivative, the spin vector components and the longitudinal and transverse components of the deviation. The spin-curvature coupling is shown to play a crucial role in controlling the change in deviation. We then use this result to investigate the changes in the form and expressions of the net GW signal as well as our understanding of GW memory, in the presence of spin. We conclude with our attempts on the measurability of this spin-induced effect vis-a-vis present GW observations.
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Quantum Physics

To Scale Up or To Scale Out: Evaluating Space-Time Costs of Compiled Logical Circuits on Modular Superconducting Quantum Processors

Modular integration has emerged as the main pathway for scaling superconducting quantum processing units (QPUs) beyond the constraints of fabrication yield and physical footprint. Currently, two primary strategies lead this effort. Mirroring the "Scaling Up" and "Scaling Out" approaches in GPU architectures and AI infrastructures, these are: chiplet-based scaling, which preserves dense connectivity and high gate fidelity at the expense of engineering complexity, and distributed architectures, which decouple system scaling from monolithic QPU advancements at the expense of sparser connectivity and lower interconnect quality. To evaluate these approaches, we introduce a quantitative stress test measuring the execution cost of a dense workload of random logical entangling operations using a surface code scheme. Using a dedicated compiler, we compute the space-time cost as the number of network nodes increases, analysing this scaling behaviour across various surface code distances, Bell-state fidelities, and Bell-pair generation times. We find that distributed architectures incur an up to exponential space-time performance penalty compared to an effectively monolithic architecture across all simulations. Our results also show that as the network grows, this penalty manifests in two distinct scaling regimes: a noise-dominated regime constrained by insufficient Bell-state fidelity and generation rates, and a connectivity-dominated regime bottlenecked by lattice-surgery routing congestion.
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All authors Nikiforos Paraskevopoulos, Sebastian de Bone, Mick Christophersen, Simon Storz, A. Mert Bozkurt, Arno Bargerbos, Sebastian Feld

High Energy Astrophysical Phenomena

Investigating the Multiwavelength Emission of Binary SMBH Candidate SDSS J095036.75+512838.1

We present results from a multiwavelength study of the binary AGN candidate SDSS J095036.75+512838.1, which was identified as a candidate binary SMBH system due to its significant and variable broad H$\beta$ line shifts. We use available infrared-to-X-ray data to investigate the system's accretion properties. Analyzing recent Chandra observations, we characterize the X-ray emission and test the binary SMBH hypothesis. We find that the X-ray spectrum is well-modeled as a single AGN, with a 2–10 keV luminosity of $1.3 \times10^{43}$ erg s$^{-1}$. By assembling a comprehensive multiwavelength spectral energy distribution, we further examine the possibility of circumbinary accretion. The infrared-optical emission matches that expected from a single AGN, though we observe an excess in emission between $\sim 9500-19000 \r{A}$ and a deficit near $\sim 2600 \r{A}$. Archival optical spectra also suggest a deficit near $\sim 8500 \r{A}$. We investigate whether these SED anomalies can be explained by long-term variability or interstellar reddening. We find no evidence of dimming, while reddening can account for the deficit in UV emission. However, the origin of the near-infrared excess remains unclear. Ultimately, the SED of SDSS J095036 is well described by emission from a single, reddened AGN. Future high-resolution infrared and X-ray spectral observations will be crucial for disentangling the origin of the infrared excess and testing the binary SMBH scenario in SDSS J095036.
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All authors Cassandra Daniele, Adi Foord, Jessie Runnoe, Michael Eracleous, Niana N. Mohammed

Nuclear Theory

Trace Anomaly and Effective Topological Sources in Neutron Stars

This work investigates whether the trace anomaly can diagnose the stellar response to a topological scalar field in tensor multi-scalar gravity. Eleven cold tabulated equations of state (EoSs) were examined, with six selected after conservative GR stability and speed of sound checks over the tabulated density range. Their fiducial topological configurations were compared with the corresponding GR models under complementary matching prescriptions. After controlling for stellar mass and EoS dependence, the GR trace source strength $S_T$ remained strongly correlated with the topological mass response, with a partial Spearman coefficient $\rho = 0.975$ within the sampled fiducial sequences. Near $1.4\,M_\odot$, the topological configurations were systematically more compact, with reductions in the Jordan frame radius of $6.7$–$8.7\%$ at fixed baryonic mass and $0.87$–$1.29\,\mathrm{km}$ at fixed gravitational mass. These shifts are comparable to current uncertainties from the Neutron Star Interior Composition Explorer (NICER) and their observational impact depends on the source. Despite the global deformation, the interior effective source remained dominated by matter, with a median topological contribution of about $0.8\%$. The GR matter trace therefore emerges as a useful diagnostic of the fiducial topological stellar response.
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High Energy Physics (Theory)

Threshold Corrections in Heterotic String Theory from Conformal Perturbation Theory

We use conformal perturbation theory to compute one-loop threshold corrections to the Kähler potential of the heterotic string. For this we consider the theory compactified at the Gepner point of the quintic, that is at a highly stringy point of its moduli space. To obtain the corrections, we compute how the weights of the lightest states of the worldsheet theory shift at second order in conformal perturbation theory. This approach can be used to obtain the one-loop correction to all orders in $\alpha'$.
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High Energy Physics (Phenomenology)

Poles in $\pi N$ scattering from forward dispersion relations and revised total cross-section data

We present a model-independent calculation of $\pi N$ forward dispersion relations and their analytic continuation to the complex plane, using a revised set of $\pi^\pm p$ total cross-section data up to 3 GeV, and Regge asymptotics above. Up to that energy, we find four stable poles for each isospin combination. The lightest pole in the $I=3/2$ channel corresponds to the $\Delta(1232)$ resonance, while the lightest in the $I=1/2$ channel corresponds to the Roper resonance, even though the latter is imperceptible in the data. We extract their pole parameters and the parameter difference between the $\Delta^0$ and $\Delta^{++}$, without relying on a partial-wave analysis. The remaining poles cannot be identified with a single resonance each. They are not artifacts but the combined effect of multiple resonances unresolved by total cross-section data alone. Finally, we write sum rules relating the residues of these constituent resonances to the residues of the poles extracted from the dispersive representation.
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Cosmology and Nongalactic Astrophysics

One-point matter PDFs beyond TopHat filters

We study the one-point probability distribution function (PDF) for matter densities averaged with an arbitrary spherically symmetric window function. The PDF is analytically modeled within the path integral framework, enabling a non-perturbative description of large-scale structure. It contains a leading order contribution controlled by the spherically symmetric gravitational collapse dynamics, as well as an order-one factor arising from aspherical fluctuations. We develop a numerical pipeline to compute the leading spherical-collapse part of the PDF and apply it to a family of window functions interpolating between the TopHat and Gaussian filters in coordinate space, as well as to a window function with non-monotonic radial dependence. We find that the PDF weakly depends on the choice of the filter, provided the width of the filter is normalized to yield a fixed linear averaged density variance. For each filter and each value of the averaged density, our pipeline gives the most probable density profile. We find that these profiles vastly differ for different filters in the case of overdensities, but closely follow a universal curve at underdensities. We obtain a perturbative expression for the aspherical part of the PDF valid at small density contrasts. We find from it that all PDFs are equally sensitive to the effective field theory (EFT) corrections accounting for short-scale clustering, regardless of how smooth the filter's boundary is. We test our PDF model against the results of high-resolution N-body simulations. The agreement is excellent for filters with widths larger than 10 Mpc/h. Small discrepancies at a few percent level arise for narrower filters and are interpreted as higher-order perturbative corrections.
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Instrumentation and Methods for Astrophysics

High-contrast aperture masking interferometry: detecting companions within the diffraction limit

The pursuit of the direct discovery and characterization of Earth-like exoplanets has motivated high contrast imaging surveys using coronagraphs with narrow inner working angles. Traditional imaging methods, however, are limited by the size of the on-axis PSF and typically only detect companions at angular separations of > 2$\lambda$/D. Meanwhile, non-redundant masking (NRM) techniques have been used with single-aperture telescopes to interferometrically resolve astrophysical features at angular scales within the diffraction limit, but NRM interferometry faces sensitivity issues for high-contrast objects. In this project, we investigate utilizing high contrast coronagraphy in conjunction with NRM interferometry. We conduct a preliminary investigation of this combined architecture with the goal of determining the potential bounds of performance and discovery space for high-contrast targets within the inner working angle of traditional high-contrast imaging. We predict an improvement in the achievable contrast for photon-limited observations by combining the techniques, and we also develop estimates for wavefront stability requirements for the system.
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High Energy Physics (Theory)

Decomposing Grassmann Monomials for Superfield Expansions

Superspace extends spacetime by anticommuting Grassmann coordinates, whose indices may transform under spin and flavour groups. Decomposing Grassmann monomials into independent invariant structures is a central step in constructing superfield expansions, but becomes increasingly difficult in extended superspace. We present a general representation-theoretic procedure for decomposing the space $\Lambda^n(\mathbb{C}^{d_S}\otimes \mathbb{C}^{d_F})$, where $d_S$ and $d_F$ are the dimensions of the spin and flavour representations. The branching multiplicities for $\mathrm{GL}(m)\downarrow{\mathrm{Sp}(m)}$ and $\mathrm{GL}(m)\downarrow{\mathrm{SO}(m)}$ are computed by exact Weyl-character comparison at deterministic rational sample points, avoiding Littlewood-Richardson modification rules. We establish completeness of the character ansatz and analyse the computational complexity, showing that it is polynomial in the number of partitions of $n$ and in the group rank, without dependence on Littlewood-Richardson combinatorics. We validate the resulting decompositions via dimension checks. We provide an accompanying standalone Julia script which implements this algorithm for groups of arbitrary rank, and produces the explicit contractions with invariant tensors.
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Cosmology and Nongalactic Astrophysics

On what scales does strong lensing robustly constrain the mass profile of low-mass perturbers?

Galaxy-galaxy strong gravitational lensing is an established method to detect and characterise low-mass haloes, which are otherwise too faint to be directly observed. Recent analyses have shown empirically that there exists a characteristic radius within which the projected enclosed mass of these haloes can be robustly measured. Here we provide a physically and mathematically motivated definition of this robust radius based on the Fisher information matrix. We show that for any spherically symmetric smooth profile with at least two free parameters, there exists a pivot radius at which estimates of the projected mass become decorrelated from the local logarithmic slope and have minimum relative uncertainty. As a result, the projected mass within this radius can be recovered consistently by any profile that fits the data well enough. This robust radius coincides, to leading order, with the weighted geometric mean of the arc pixel distances from the halo, where the weights depend on the perturber deflection angle, the macro-model magnification, and the source surface brightness gradient. Beyond leading order, corrections are of order the weighted log-width of the arc. The data constraining power on the local properties of the halo profile beyond amplitude is shown to depend on the radial leverage of the arc around the perturber, and on the imprint of the perturber deflection angle on high signal-to-noise-ratio pixels. Our definition generalises to both subhaloes and line-of-sight haloes and naturally captures the important physical aspects of the problem and the effect of the data resolution and signal-to-noise ratio.
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Quantum Physics

Practical Error Suppression and Mitigation for Reliable Quantum Computing

Quantum computing is entering a transitional regime between noisy intermediate-scale quantum (NISQ) processing and early fault-tolerant quantum computation (FTQC), in which increasingly capable hardware is beginning to support repeated syndrome measurements, partial error correction, and logical-qubit operations, while residual physical and logical errors remain non-negligible. In this regime, error suppression, error mitigation, and quantum error correction are increasingly better viewed as complementary layers of a unified error-reduction strategy rather than as separate approaches, with each acting at a different stage of the quantum computation to improve simulation reliability. Thus, in this review, we provide a practical and forward-looking overview of the principal hardware error sources and the corresponding error suppression and mitigation methods for reducing their impact across the current NISQ-FTQC transition. We discuss hardware-aware circuit design, coherent-error suppression, readout mitigation, noise extrapolation, classical inference, and software-supported workflows, with particular emphasis on their implementation on actual quantum processors. We further examine how error mitigation techniques can be adapted to encoded and logical-qubit settings so that they can operate alongside quantum error correction to suppress residual logical errors and improve the accuracy of computation in the early fault-tolerant regime.
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All authors Han-Ze Li, Mengjie Yang, Xianquan Yan, Dax Enshan Koh, Ching Hua Lee, Ruizhe Shen

High Energy Physics (Theory)

Alakazam: Symbolic Tensor Algebra for Field Theory in Julia

We present "Alakazam", a Julia package for performing symbolic manipulations of tensor expressions arising in the study of field theories and quantum mechanics. This will serve as a powerful tool for studying spacetime and supersymmetric structures, including support for calculations in superspace. The package implements many key features such as raising and lowering indices, simplification of terms with dummy indices, replacement patterns, differential and variational calculus, bosonic and fermionic grading, gamma matrix identities, and Lie brackets and commutators. We present notable speed improvements over established systems. Some possible applications include the study of descendants and invariants.
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High Energy Physics (Phenomenology)

Tunneling from a Slowly Rolling Multifield Background Using Tadpole Subtraction

We study semiclassical tunneling in scalar field theories with slowly evolving homogeneous backgrounds. We formulate the problem by combining tadpole subtraction with an adiabatic expansion: the former maps the rolling system to an instantaneous multi-field tunneling problem, while the latter systematically tracks the slow evolution of the background. This formulation is particularly useful for tunneling during slow-roll inflation, where the tunneling direction may be transverse to the rolling inflaton direction. For a time-reflection-symmetric bounce on a fixed on-shell geometry, we show that the real tunneling exponent receives no direct correction linear in the rolling velocity. The tunneling rate nevertheless drifts along the rolling trajectory because the frozen tadpole-subtracted potential evolves. We also find that the exponent approaches a finite but nonanalytic limit as the tangential curvature vanishes, suggesting that a weakly tachyonic tangential direction can yield an exponent of the same order.
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Earth and Planetary Astrophysics

Leveraging Impact Parameter to Mitigate the Transit Light Source Effect: Early Insights from TRAPPIST-1

Stellar activity complicates exoplanet transmission spectra, particularly for smaller planets around M dwarfs with JWST. The transit light source (TLS) effect, the imprinting of spectral differences between the average stellar disk and the occulted transit chord onto the transmission spectrum, makes it challenging to directly use the out-of-transit spectrum to correct for stellar contamination. Theory and observations suggest that spots may concentrate towards higher latitudes when the Coriolis force is substantial relative to buoyancy, leaving the equatorial region relatively quiet. Here, we evaluate how the latitudinal distribution of active regions shapes the strength of the TLS effect for planets spanning a range of impact parameters ($b$), using TRAPPIST-1 as a testbed. We first construct a fiducial model to illustrate two distribution regimes. With our model, the moderate-$b$ outer TRAPPIST-1 planets (f, g, h) occult a more typical region of the stellar disk than the inner planets and are thereby less affected by the TLS effect, though their bias may vary more from visit-to-visit as these active regions evolve with time. More generally, our results imply an impact parameter "sweet spot" for atmospheric characterization, independent of the sign of the active region temperature contrast, whose location depends on the distribution of active regions. The distribution may be revealed by transit residuals as multiple planets probe different latitudes, while longitudes are sampled in time, such that the variance and frequency of the correlated scatter could constrain active-region filling factors, sizes, and separations.
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All authors Ana Glidden, Alexander I. Shapiro, Sara Seager, Nadiia Kostogryz, Valeriy Vasilyev, Roeland P. van der Marel, Julien de Wit, Benjamin V. Rackham, Prajwal Niraula, Natalie H. Allen, Jingcheng Huang, Nikole K. Lewis, Zifan Lin, Jacob Lustig-Yaeger, Ryan J. MacDonald, Brett M. Morris, Elijah Mullens, Kevin B. Stevenson, Jeff A. Valenti, Daniel Valentine, Hannah R. Wakeford, C. Matt Mountain

Soft Condensed Matter

The friction-era VOS amplitude of a $\mathbb{Z}_2$ string network from nematic disclination data

A tangle of line defects coarsens as the mean spacing $L$ between neighbouring lines grows. In a viscous medium the motion is overdamped, and the velocity-dependent one-scale (VOS) model predicts a late-time attractor $L^{2}=\mathcal{A}\,\ell_d\,t$, with $\ell_d=T/\Gamma$ the ratio of line tension to drag and $\mathcal{A}$ a dimensionless amplitude. The growth law $L\propto t^{1/2}$ holds for every value of the three model parameters—the momentum parameter $k\le1$, the sink coefficient $\tilde{c}$, and the curvature ratio $\lambda\equiv R/L$—since all three enter only through $\mathcal{A}=\kappa(\kappa+\tilde{c})$, $\kappa\equiv k/\lambda$. Thus, the exponent constrains none of them, and the amplitude is the only quantity a density history can deliver. We measure it from the disclination data of Chuang, Turok and Yurke on a nematic liquid crystal, whose companion measurement of loop collapse fixes $\ell_d$ on the same samples, canceling the 5CB material constants. Treating the unmatched per-quench $\ell_d$ as a nuisance parameter with a Gaussian prior and marginalizing it analytically, we obtain $\mathcal{A}=10.0^{+1.3}_{-1.1}$ from the three quenches in the $234~\mu$m cell; the fourth, the only one in the thinner $158~\mu$m cell, gives $\mathcal{A}=3.0^{+0.8}_{-0.6}$ and is fitted separately. Converting either into $\tilde{c}$ requires $\lambda$, which these data do not determine, so the result is a curve, $\tilde{c}(\lambda)=\mathcal{A}\lambda/k-k/\lambda$, not a number. At $\lambda=1$ with $k\le1$ they give $\tilde{c}\ge9.0$ and $\tilde{c}\ge2.0$, against $\tilde{c}=0.23$–$0.57$ from relativistic $U(1)$ simulations, values reached only at $\lambda\simeq0.33$–$0.35$ and $0.62$–$0.68$. We know of no VOS calibration for a cosmological $\mathbb{Z}_2$ network, so we cannot attribute the excess to topology, and we list what a repeat experiment must measure.
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Quantum Physics

Granthi: Higher-Order Quantum Programming via Unitary Wiring

Many mainstream quantum programming languages confine higher-order structure to a classical host while restricting the quantum layer to first-order operations on qubits. This paper presents Granthi, a purely unitary higher-order quantum programming language built on three design commitments: quantum programs are first-class values that may be passed, returned, and coherently composed; additive structure is tag-preserving routing rather than observational branching, so control may remain in superposition; and programmer-facing finite label types with staged reversible-operation bindings provide domain-level control spaces without exposing tag management. These bindings are eliminated by elaboration before Source typing. Granthi deterministically normalizes each Source program to a canonical wiring form. Every well-typed Source program, including a term of function type, has a unitary boundary interpretation. Under backend correctness (BC), the reference compiler produces a unitary circuit realizing that interpretation. Granthi's currently supported executable fragment is implemented end-to-end: an OCaml DSL elaborates surface programs through a higher-order Core IR to executable quantum circuits via pytket. The language directly supports the pure-unitary quantum switch for explicitly supplied operations; closed instances compile to static circuits. It also supports interference on control-flow history and structured finite control, all within the purely unitary fragment
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Computational Physics · Cross-listed from cs.LG

Shared Physics Responses Recover Hidden Rankings in Neural Operator Libraries

Selecting the optimal neural-operator prediction during deployment is challenging when high-fidelity reference solutions are unavailable. We demonstrate that under a squared Hilbert-space loss, ranking a finite model library depends strictly on the low-dimensional span of candidate differences, allowing us to score all models simultaneously using a single anchor-based linearized response of the governing equation. This shared physical diagnostic accurately recovered over 99.6% of pairwise preferences and 99.0% of optimal checkpoints across diverse Fourier and convolutional operator libraries for fluid, reaction-diffusion, and wave dynamics. Furthermore, the corrected physical proxy frequently outperformed the best individual candidates, and we establish computable sufficient conditions that rigorously certify exact decisions for strongly monotone discretizations. By exploiting the local dynamical response rather than raw defect magnitude, this framework enables the reliable and highly efficient deployment of scientific surrogates without requiring ground-truth data.
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Computational Physics · Cross-listed from cs.LG

Wrong-Physics Backdoors in Neural PDE Operators

Neural PDE operators are increasingly trained on reusable solver archives, yet validation often relies on clean prediction error and parameter-agnostic plausibility checks. We introduce cross-parameter relinking, a data-poisoning primitive that makes a triggered input select a valid solution from the same PDE family under an incorrect physical parameter. We term this a wrong-physics backdoor: the output remains physically plausible but is wrong for the intended parameter. The attack exploits tensor-to-parameter provenance failures in multi-parameter archives by stamping the surrogate input and relinking its supervision to a cached alternate-parameter solution for the same latent sample. Across 476 attack campaigns, we evaluate Burgers, advection-diffusion, two-dimensional Navier-Stokes, and an elliptic Poisson case. Fourier Neural Operators and DeepONet provide the primary evidence, with Transformer, GRU, and LSTM models as support. FNO reaches a backdoor success rate of 1.0000 on both advection-diffusion and two-dimensional Navier-Stokes while retaining low clean relative L2 error. Clean-label, label-only, and shuffled controls show that high attack success alone is insufficient: successful attacks must move predictions toward the intended alternate-physics target while preserving bounded clean error. These results expose a structural validation gap: smoothness or generic solver-like behavior is insufficient unless the provenance of the intended physical parameter is also verified.
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Physics and Society

Peer-Voted LLM-Agent Stress Tests Find Feed-Induced Lexical Convergence but No Reliable Matched-Exposure Advantage for Distributed Sources

Population-level behavior in large-language-model (LLM) agents cannot be characterized by single-agent benchmarks. We introduce PV-SST, a peer-voted social-platform testbed, and report a separately frozen, preregistered matched-exposure experiment spanning four topics, four unused seeds, four open-weight model families, and three prespecified larger variants. The experiment comprises 448 trials and 112 complete model-by-topic-by-seed blocks. Relative to a topic-only control, a feed of previous-round peer posts ranked by peer-generated likes increases final-round lexical similarity in both the four-family core panel (paired mean difference +0.0082 TF-IDF cosine units, 95% block-bootstrap CI [0.0043, 0.0121], randomization p=0.000105, n=64 blocks) and the three-variant size extension (+0.0109 [0.0069, 0.0151], p=0.000001, n=48). This contrast bundles peer-post exposure with ranking and therefore does not identify a ranking-only effect. Opposite-side survival falls in the core panel (-3.9 percentage points [-6.8, -1.6], p=0.0068) but not conclusively in the larger variants (-1.0 pp [-3.1, 0.4], p=0.50). Holding adversarial impressions fixed, four distributed sources do not reliably move honest-agent stance more than one source. The preregistered distributed-minus-single contrast is positive but inconclusive in the core panel (+0.057 [-0.009, 0.125], p=0.112) and negative in the larger variants (-0.040 [-0.113, 0.035], p=0.332), failing the prespecified cross-model and cross-topic consistency criterion. Thus the robust result is lexical convergence under the tested peer-ranked feed, not general opinion capture or a general coordination advantage. The study evaluates synthetic LLM-agent populations; it does not estimate effects on people or production platforms.
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Instrumentation and Methods for Astrophysics

A Multi-instrument Generalized Lomb-Scargle Periodogram Implementation

We present an implementation of the well-known and broadly used Generalized Lomb-Scargle Periodogram (GLS) which simultaneously takes into account individual offsets introduced in the data by different instruments: a "multi-instrument" GLS periodogram. While the algorithm itself is not new, the simple closed form implementation we provide, to our knowledge, is. We showcase an application of our multi-instrument GLS on radial-velocity data of the hot Jupiter TOI-481 b, whose period is recovered with a higher significance compared to the standard GLS approach. The code is available on GitHub.
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Quantum Physics

Comment on "Scalable Quantum Machine Learning: Trainability, Expressivity and Efficiency": Polynomial Evaluation of the Triplet-Block Readout

We examine the classical-cost claim for the triplet-block two-body readout in arXiv:2607.24014v1. The Gaussian-state expansion used there gives an $O(2^{2k/3}\mathrm{poly}(n))$ classical algorithm, but it is not necessary for fixed-body observables. The triplet-block input has an explicitly computable diagonal two-particle reduced density matrix, which passive fermionic linear optics propagates through $\bigwedge^2 W$. This gives a deterministic $O(n^4)$ algorithm for the complete correlator vector $(\langle n_i n_j\rangle)_{i<j}$, independently of $k$ and the fermionic-linear-optics extent. More generally, every number-conserving fixed-$r$-body expectation is polynomially computable whenever the input $r$-particle reduced density matrix is classically available; if that matrix is diagonal, all diagonal correlators are computable in $O(n^{2r})$ time. This invalidates the algorithm-relative exponential-cost conclusion for the supervised two-body readout, without affecting the gradient-variance, barren-plateau, parameter-shift, or sampling-hardness results.
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Materials Science

An LLM agent for end-to-end computational materials discovery

Coordinating multi-scale tasks is an effective strategy for computational materials discovery, yet the diverse algorithms and tools involved make this process highly challenging. Here we present DREAMS, a large language model (LLM)-based agent system capable of executing the entire screening pipeline for metal-organic frameworks (MOFs). DREAMS processes a large body of MOF literature, links publications to their crystal structures, and curates them into a computation-ready database, which is then screened with progressively more expensive simulations. The promising candidates identified for separation under wet flue gas conditions all originate from independent studies. By bridging the heterogeneous stages from literature mining to high-throughput simulation, DREAMS operates across application domains and enables even non-experts to discover high-performance materials in an end-to-end, automated manner.
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All authors Chen Yuntong, Huang Lijiang, Li Yingqi, Liu Yu, Zhao Dan, Sun Mingqi, Ju Chentian, Liu Yanbing, Li Xiao-Yan, Zhao Guobin

Quantum Physics

Group-theoretic treatment of strong light-matter coupling with an arbitrary number of excitations

Strong light-matter interactions in optical microcavities give rise to hybrid light-matter states known as polaritons. While actively used in modern technologies, theoretical descriptions of such systems are often restricted to the single-excitation case, limiting their ability to capture many-excitation physics and hindering further technological advancements. Here, by exploiting the combinatorial structure of quantum emitters, we investigate the Tavis-Cummings model with arbitrary number of excitations. We derive the structure and properties of its eigensystem and identify allowed radiative transitions in systems of realistic size scales. Our work reveals new behavior inaccessible to the few-excitation regime, while also providing a framework to reduce the computational complexity of similar systems with exponentially growing Hilbert spaces.
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All authors Antti Peltola, Olli Siltanen, Kimmo Luoma, Konstantinos S. Daskalakis

Astrophysics of Galaxies

An Optical Illusion: High Electron Densities Create Extremely Metal-Poor Galaxy Impostors

JWST has enabled the discovery of dozens of extremely metal-poor galaxies (EMPGs) with metallicities below $5\%\,Z_{\odot}$, representing a significant leap toward detecting the first galaxies without metals. However, accurate metallicity measurements require careful determination of physical conditions in the ionized gas. In this paper, we study four galaxies that appear to be EMPGs when analyzed using the direct $T_e$ method with the common low-density assumption ($n_e=10^3\,{\rm cm}^{-3}$). To test whether their metal-poor status holds when accurately measuring the density, we apply the direct method with a self-consistent determination of electron temperature ($T_e$) and density ($n_e$) in the high-ionization zone using the [OIII]$\lambda$5008, [OIII]$\lambda$4364, and [OIII]$\lambda$1666 lines, using JWST/NIRSpec data from the SPURS program in the Abell 2744 lensed field. We find that three out of four galaxies in our sample have extremely high electron densities ($n_e \sim 10^{5}-10^{6}\,{\rm cm^{-3}}$), which suppress the [OIII]$\lambda$5008 line and lead to underestimates of metallicity by up to $\sim1.1\,$dex when this density is not accounted for, and have true metallicities of 12+log(O/H) $\sim7.3-8.2$. Failure to account for high densities can therefore lead to systematic misclassification of metal-poor galaxies and biased conclusions about early chemical enrichment.
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All authors Tiger Yu-Yang Hsiao, Danielle A. Berg, Steven L. Finkelstein, Ansh R. Gupta, Zorayda Martinez, Anthony J. Taylor, Hollis B. Akins, Oscar A. Chavez Ortiz, John Chisholm, Lukas J. Furtak, Vasily Kokorev

High Energy Physics (Theory)

Maximal Total Quantum Dimension at Bounded Rank in WZW Modular Tensor Categories

We determine the maximal torus topological entanglement entropy (TEE) at bounded torus ground-state degeneracy within simply connected untwisted Wess–Zumino–Witten theories. For a fixed modular tensor category $\mathcal C$, maximization over normalized torus ground states gives $\max_\psi\Gamma_{T^2}(\psi)=2\log{\mathcal D(\mathcal C)}$, attained in particular by the vacuum-flux state. The remaining problem is therefore to maximize total $\mathcal D$ at bounded categorical rank. For a simple WZW category $\mathcal C(\mathfrak g,k)$, write $r(\mathfrak g,k)$ and $\mathcal D(\mathfrak g,k)$ for its categorical rank and total quantum dimension, and define $F_{\WZW}(R)=\sup_{r(\mathfrak g,k)\leq R}2\log\mathcal D(\mathfrak g,k)$. We prove the sharp asymptotic law $\lim_{R\to\infty}\frac{F_{\WZW}(R)}{(\log_2R)^2} =\frac{7\zeta(3)}{4\pi^2}.$ The balanced symplectic sequence $Sp(2n)_n$ attains the coefficient. The constant arises from the odd Fourier modes of the type-$C$ root product at equal rank and level. A sharp entropy–spectral inequality, rank-level duality, and fixed-rank estimates give the global upper bound. A separate corollary extends the same leading law to semisimple WZW categories,equivalently finite Deligne products of simple factors. The unrestricted TQFT envelope remains open; the theorem is sharp within the stated WZW class and supplies a constructive lower bound for the general problem.
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Atomic Physics

A Protocol for Shielding-Enhanced Loading of Single Polar Molecules into Optical Tweezers

We propose the high-fidelity preparation of single bosonic molecules in optical tweezers starting from small tweezer-trapped molecular ensembles. Our scheme combines a static electric field and a microwave field to generate strong, tunable, anisotropic interactions that shield the molecules against two-body collisional loss. We show that this shielding eliminates all long-range bound states, preventing three-body recombination. This elimination persists for all microwave ellipticities, including the experimentally practical limit of linear polarization. Application of an additional electric field gradient can be used to induce controlled spilling of strongly interacting molecules out of the trap until one remains. With realistic experimental parameters, we estimate that single tweezer-trapped NaCs molecules can be isolated from a pair with fidelities exceeding 99%, and $> 95\%$ per site across an array. These results establish collisional shielding with electric fields as an effective tool for preparing highly-filled tweezer arrays of polar molecules.
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All authors Reuben R. W. Wang, Christian H. Nunez, Conner Williams, Amanda Younes, Li Du, H. R. Sadeghpour, Kang-Kuen Ni

Strongly Correlated Electrons

Torus Berry Data Determine All-Genus Abelian Topological Orders

We show that for Abelian Chern-Simons topological orders, torus Berry matrices determine the all-genus extended TQFT. We identify the topological part of the projective Berry holonomy under metric deformations with the mapping-class-group representation of the Abelian Chern-Simons TQFT and prove that the normalized torus data reconstruct its finite quadratic module (G,q). Recent work showed that (G,q) classifies the extended theory up to symmetric monoidal natural isomorphism, and that the associated Abelian defect extension is determined by the pointed modular category C(G,q) arising from the same finite quadratic-module data. Therefore genus-one Berry data determine not only the all-genus bulk theory but also its associated defect structures without choosing a K-matrix presentation. We also prove that, for normalized character row errors $\delta$<21.96%, nearest-row decoding recovers the Abelian fusion algebra independently of the number of anyons. The result applies to Abelian fractional quantum Hall and spin-liquid phases described by even-lattice Chern-Simons theories.
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High Energy Physics (Phenomenology)

Production of quarkonium pairs via the fragmentation mechanism

In this manuscript, we analyze the contribution of fragmentation mechanisms to the inclusive hadroproduction of heavy quarkonium pairs, taking into account both single- and double-hadron (dihadron) fragmentation channels. To estimate the contribution of the latter mechanism, we construct a microscopic perturbative model of the dihadron fragmentation function, which is valid in the limit of large invariant masses of the heavy quarkonium pair. Using the Color Glass Condensate framework to evaluate the $Q\bar{Q}$ production amplitude, we find that in LHC kinematics, the single fragmentation of heavy quarks into quarkonium is only a minor correction, whereas dihadron fragmentation can provide a sizable contribution, on par with the contributions of single- and double-parton scattering.
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Statistical Mechanics

The Memory Hidden in Response Fluctuations: Trajectory-Level Fluctuation-Response Theory and Inequalities for Non-Markovian Jump Dynamics

Modern experiments often record nonequilibrium dynamics as sequences of discrete events whose rates depend on the realized past. We develop a fluctuation-response theory for such non-Markovian jump processes directly on the observed event record. Memory can destroy a closed master equation for the state probabilities. Each transition count nevertheless obeys an exact stochastic equation. After the history-dependent mean event tendency is subtracted, the remaining random increment is a martingale increment–the part of the event that cannot be predicted from the past. Martingale increments associated with different transitions and different times are orthogonal. These increments form a complete orthogonal basis for the random deviation of any observable measured from the record, such as a current, occupation time, or event count. The coefficient of a given increment is the event-consequence kernel. It measures how that event changes the predicted final observable, relative to continuing without the event, for the particular history already realized. Multiplying this kernel by the event intensity gives the history-conditioned response to perturbing the corresponding transition rate. Thus, the intensity-normalized response is exactly the expansion coefficient of that event in the observable fluctuation. This identification yields exact finite-time and finite-frequency fluctuation-response relations. Averaging over histories leaves a nonnegative response-heterogeneity gap. The gap measures how strongly the consequence of the same event varies across histories and tests whether a proposed memory coordinate is response-sufficient. Finite-history versions can be estimated from spontaneous trajectories. Bounding the logarithmic rate sensitivity further gives response-kinetic uncertainty relations controlled by dynamical activity.
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Quantum Gases

Competing triangular and stripe supersolid orders in a dipolar quantum gas

Supersolids are exotic quantum states in which long-range phase coherence coexists, and may interplay, with emergent spatial orders. A particularly rich phase diagram featuring several competing spatial orders is predicted for dipolar supersolids with two-dimensional crystals, yet the experimental observation of this structural variety has remained limited. Here we experimentally form competing triangular and stripe density-modulated states in a quantum gas of highly magnetic atoms confined in a surfboard-shaped trap by tuning contact interaction strength and dipole orientation. We define a structural order parameter and study its statistical behavior. Thereby, we identify both the triangular and stripe phases and the transition between them, the associated critical behavior being marked by enhanced non-Gaussian fluctuations. Furthermore, we observe each spatial structure in both the phase-coherent supersolid regime and the phase-incoherent insulating one, near and far from the unmodulated-to-modulated transition, respectively. Our results establish a versatile platform in which multiple phases of the two-dimensional-supersolid phase diagram, and more generally, intertwined symmetry-breaking phenomena, can be investigated.
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All authors Karthik Chandrashekara, Christian Gölzhäuser, Lily Platt, Jianshun Gao, Julian Kusch, Lennart Hoenen, Manon Ballu, Wyatt Kirkby, Lauriane Chomaz