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All of arXiv

Wednesday 7 October

Mathematical Physics

Finite- and long-range spin-wave free-energy asymptotics for the two-dimensional quantum Heisenberg ferromagnet

Andreas Klippel

For the two-dimensional quantum Heisenberg ferromagnet with asymptotically radial power-law exchange, we prove the leading low-temperature free energy at every fixed spin, uniformly on the weak-field scale. We obtain fractional and logarithmically corrected laws associated with the dispersions predicted in [16, 17]. Quantum Monte Carlo simulations support the associated anomalous magnon dispersions for spin one-half [20]. For kernels with finite second moment, we also extend the nearest-neighbour theorem [14], generalizing Takahashi's quadratic law [21] and its weak-field dependence [11].
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Cryptography and Security

DITTO: A Context-aware Pickle-based Pre-Trained Model Scanner for Effective Security Audits

Qiaolin Qin, Wanpeng Li, Benoit Baudry et al. (+3 more)

Pre-trained models (PTMs) are widely distributed as serialized binaries, but their reuse often exposes software supply chains to deserialization attacks. Despite the emergence of safer serialization formats, the unsafe Pickle format remains prevalent: our analysis of over 10,000 popular Hugging Face repositories reveals that 9.3% rely on Pickle. While many defense mechanisms have been proposed, state-of-the-art model scanners suffer from a coverage-precision gap, missing security-sensitive behaviors and generating excessive false alerts. In this paper, we introduce DITTO, the first stack-based, context-aware scanner for Pickle-based PTMs. DITTO faithfully tracks Pickle virtual machine state transitions and performs context-aware semantic analysis to infer model intentions. We also present PickleBench, a benchmark of 959 benign and 92 malicious real-world models, including extension registry attacks previously missed by existing tools. Across multiple evaluations, DITTO achieves 100% scanning coverage, a 0% false-negative rate, and a 0.7% false-positive rate, yielding an F1 score of 0.966, significantly outperforming state-of-the-art scanners. By minimizing false alerts while preserving detection accuracy, DITTO generates actionable security reports with contextual evidence, enabling safe PTM reuse and strengthening software supply chain integrity.
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All authors Qiaolin Qin, Wanpeng Li, Benoit Baudry, Lorenzo De Carli, Heng Li, Ettore Merlo

High Energy Physics (Theory)

The hidden sunrise in the energy-energy correlator

Matthew D. Schwartz and Xiaoyuan Zhang

The energy-energy correlator (EEC) is one of a handful of collider observables that can be computed analytically to high orders. As an energy-weighted cross-section, it exposes features of quantum field theory that scattering amplitudes do not, and it can be compared directly to data. As with scattering amplitudes, the analytic expressions require special functions beyond polylogarithms. In Henn et al., the EEC was computed to next-to-next-to-leading order (NNLO) for $\mathcal{N}=4$ super Yang-Mills (SYM) theory, and the result is expressed in terms of both harmonic polylogarithms (HPLs) and one two-fold integral, which contains elliptic curves. In this work, we report a complete result including the remaining elliptic sector, which is closely related to the sunrise Feynman integrals. We find the $j$-invariants of the EEC and the sunrise agree identically under a Möbius map, and thus the elliptic sector in the EEC lives on the $\Gamma_1(6)$ modular curve of the sunrise integral. We then express the answer in terms of iterated Eisenstein integrals, which can be evaluated to high precision quickly. The analytic form also allows a first study of the EEC Landau bootstrap, and the understanding of its function space in $\mathcal{N}=4$ SYM offers a concrete handle on the elliptic sector of the EEC in QCD. Many of the technical results in this paper were completed with AI under human supervision.
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Mesoscale and Nanoscale Physics

Hydrodynamic Anomalous Hall Effect in a Two-Dimensional Dirac Fluid

A. Levchenko and D. A. Pesin

In ultraclean conductors, electron-electron collisions can make transport hydrodynamic. In a Berry-curved band, these collisions can also produce two-particle coordinate shifts, which contribute to the anomalous Hall current in the presence of a transport electric field. We develop a kinetic theory of this contribution for a two-dimensional massive Dirac Fermi liquid with weak contact interactions and weak short-range disorder. The computed response is independent of interaction strength at leading Born order. Its contribution to the anomalous Hall conductivity is comparable to the thermal correction to the intrinsic anomalous Hall conductivity. The existence of the momentum zero mode of the electron-electron collision integral leads to a nontrivial frequency dependence of the anomalous Hall response considered in this work. In particular, the limits of vanishing frequency (dc) and vanishing disorder do not commute. In the dc limit, the momentum response to the transport field grows inversely with the momentum relaxation rate. This allows arbitrarily weak, energy-dependent impurity scattering to produce a finite correction by coupling conserved momentum to the modes relaxed by electron-electron scattering. This correction disappears when the clean limit is taken before the zero-frequency limit. As a result, the interaction-induced Hall response retains information about the mechanism of momentum relaxation even as the overall disorder strength tends to zero.
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Optics

Propagation-Invariant Transmission Eigenmodes in Weakly Scattering Media

J.C Osorio-Tascon and P. A. Quinto-Su

Propagation-invariant beams (PIBs) with annular angular spectra preserve their transverse intensity structure over extended propagation distances. Here, we investigate whether scattering invariant modes (SIMs) can simultaneously exhibit scattering and propagation invariance. We measure free-space and sample transmission matrices (TMs) in an orthonormal annular basis for weak, moderate, and strong scattering media and identify localized SIMs (LSIMs) whose angular spectra remain predominantly confined to one or a few neighboring rings. Under weak scattering, 75 of the 128 SIMs considered for annular localization satisfy this criterion, with LSIMs exhibiting Bessel-like propagation. Under moderate scattering, 25 LSIMs are recovered after filtering low-intensity spectral components, whereas none are found under strong scattering. Although increasing modal crosstalk progressively suppresses annular localization and nondiffracting behavior, SIMs retain higher transverse-intensity correlation over propagation than the Gaussian-like and Bessel beams in the moderate and strong regimes. These results show that annular localization enables SIMs to acquire propagation invariance when scattering is weak, whereas the enhanced propagation robustness of SIMs can persist even after this localization is lost.
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Quantum Physics

Single-shot magic state factories for quantum LDPC codes

Varun Menon, Rohan Mehta, Andi Gu et al. (+8 more)

Quantum low-density parity-check (qLDPC) codes can substantially reduce the qubit overhead of fault-tolerant quantum computation, but any useful architecture based on such codes also requires an efficient mechanism to implement non-Clifford gates in a fault-tolerant manner. We introduce a space-time-efficient magic state factory for high-rate qLDPC codes by combining the transversal non-Clifford gates of recently developed tricycle codes with single-shot four-dimensional balanced product quadcycle codes. The key ingredient is an efficient "escape" mechanism that teleports postselected logical magic states from tricycle codes to larger distance quadcycle codes. Under a standard circuit-level noise model at physical error rate $10^{-3}$, our factories produce $\mathrm{CCZ}$ states at logical error rates as low as $10^{-9}$ with 10-40 times lower space-time cost than state-of-the-art magic state generation methods. The resulting states are directly encoded in high-rate blocks suitable for computation. We identify the quadcycle codes by an AI-assisted search and show that they can serve as excellent memories capable of single-shot error correction. Finally, we present a concrete implementation of the entire factory with highly efficient atom transport on reconfigurable neutral-atom quantum computers. Together, these results provide an end-to-end, practical protocol for producing and utilizing high-fidelity magic states within a high-rate qLDPC architecture, with the lowest space-time cost to date.
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All authors Varun Menon, Rohan Mehta, Andi Gu, Andrei C. Diaconu, Daniel Bochen Tan, Xiao Xiao, Michael J. Gullans, Qian Xu, Hengyun Zhou, Mikhail D. Lukin, J. Pablo Bonilla Ataides

High Energy Physics (Phenomenology)

pyAmpliCol: fast tree-level matrix elements

Rikkert Frederix, Valentin Hirschi, Lucien Huber et al. (+3 more)

Tree-level matrix elements sit at the heart of collider event generation, but their cost rises rapidly just where additional resolved radiation becomes most important. We present pyAmpliCol, a public generator aimed at extending the practical reach of colour-resolved matrix elements to higher multiplicities. It builds on the colour-ordered, off-shell-current strategy of AmpliCol, providing fast access to individual leading-colour flows while retaining the option of next-to-leading or exact full colour. The latter introduces its own high-multiplicity bottleneck: the dense interference of factorially many colour orderings. pyAmpliCol addresses this contraction with a fast Fourier transform on the symmetric group, preserving the exact colour result while avoiding the direct pairwise sum. Representative full-colour benchmarks demonstrate substantial speedups over the reference calculations considered here. It supports Standard Model processes and a broad class of UFO models, selected or summed helicities, vectorised evaluation and controllable numerical precision. It further provides colour- and spin-correlated Born quantities and tree-level colour connections at arbitrary perturbative order, opening the same framework to local subtraction and other higher-order applications. Together, these capabilities connect high-multiplicity matrix elements to their use in event generation, merging, parton showers and precision calculations within a single generator.
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All authors Rikkert Frederix, Valentin Hirschi, Lucien Huber, Shahriar Iravanian, Ben Ruijl, Timea Vitos

High Energy Astrophysical Phenomena

Descalarization bursts from Galactic supramassive neutron stars: a kHz continuous-wave target

José Carlos Olvera M., Daniela D. Doneva, Pablo Cerdá-Durán et al. (+2 more)

In massive scalar-tensor gravity, a scalarized neutron star must shed its scalar hair as it collapses into a black hole. Using 3D simulations of a realistic rotating progenitor we show that dispersion stretches the emitted burst into a quasi-monochromatic signal in the kHz frequency range lasting $>10^4$ yr and amenable to continuous-wave methods. We find that detecting these signals in directed searches of supernova remnants without a central pulsar requires sensitivity depths of 233–762 $\rm{Hz^{-1/2}}$ with the A+-ET-CE detector network. We estimate up to $\sim3$ of these signals in transit at any observational epoch.
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All authors José Carlos Olvera M., Daniela D. Doneva, Pablo Cerdá-Durán, José A. Font, Stoytcho S. Yazadjiev

Computational Finance

Deep Learning vs. Statistical Models for Multi-Horizon Price Forecasting of Second-Hand Electronics: A Systematic Benchmark

Mateusz Buczyński, Michał Woźniak, Konrad Kaczyński et al. (+2 more)

Forecasting resale prices of used electronics is critical for subscription-based platforms where pricing errors translate directly into risk. Unlike structured financial markets, second-hand electronics exhibit high volatility, sparse listing histories, and non-normal price dynamics - yet no systematic time-series benchmark exists for this domain. This paper presents the first multi-horizon benchmark of statistical and deep learning forecasting models for used electronics price prediction. We use a large-scale dataset of daily price listings from Polish online marketplaces (January 2022 to March 2025, 100+ smartphone and laptop models) and evaluate eleven models across six horizons from 1 to 365 days, covering classical methods (ARIMA, ETS, Theta), recurrent and convolutional networks (LSTM, TCN), and modern deep architectures (N-BEATS, N-HiTS, TFT, PatchTST, Informer). Three complementary evaluation protocols assess trajectory fitness, one-shot endpoint accuracy, and cross-horizon transfer. N-BEATS achieves the lowest MAPE beyond 30 days, reaching 8.51% at 365 days versus 14.94% for the best statistical baseline - a 43% reduction. At short horizons (1-7 days), all models converge near 0.72% MAPE and the naive baseline remains competitive. A single N-BEATS model trained at 365 days generalizes to all shorter horizons, eliminating the need for horizon-specific models. N-BEATS and N-HiTS also demonstrate superior hyperparameter stability.
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All authors Mateusz Buczyński, Michał Woźniak, Konrad Kaczyński, Anna Wróblewska, Sebastian Kuk

Astrophysics of Galaxies

First uGMRT Constraints on Rotation Measure in the Radio-Quiet Seyfert Galaxy NGC 4235

Salmoli Ghosh, Preeti Kharb and Janhavi Baghel

We present a multi-frequency polarimetric study of the radio-quiet Seyfert galaxy NGC 4235 using the upgraded Giant Metrewave Radio Telescope (uGMRT), aimed at constraining the Faraday rotation properties of its kpc-scale radio emission. This marks the first-ever analysis of polarization across two frequency bands of the uGMRT and the first constraints on rotation measure (RM) at lower frequencies for a weak radio source (17.1$\pm$1.7 mJy at 1.3 GHz, 27.7$\pm$2.8 mJy at 663 MHz). We detect linearly polarized radio emission associated with the `core' and the extended lobes of NGC 4235. Broadband polarimetric analysis yields an RM value of {$\sim200$ rad m$^{-2}$} in the `core', indicating Faraday rotation by magnetized plasma external to the synchrotron-emitting regions. Using these RM constraints, we estimate an average electron density of the Faraday-rotating medium of $\sim$3$\times10^{-2}$ cm$^{-3}$ for a characteristic perturbation scale of $\sim$0.3 parsec within an assumed magnetized region of size $\sim$1.3 kpc, consistent with a diffuse magnetized sheath or AGN-driven wind. These results extend classical Faraday rotation diagnostics to the low-power, radio-quiet AGN regime and demonstrate the potential of uGMRT broadband polarimetry for probing magnetized environments in and around such AGN.
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Materials Science

Resolving the interfacial mechanical landscape of monolayer NbSe2 grown by confined epitaxy

Ye Wang

Confined epitaxy has recently emerged as a novel methodology for controlled growth of high-quality monolayer two-dimensional (2D) materials. However, mechanistic understanding remains limited to analysing nucleus adsorption and diffusion barriers. Here, I discover that van der Waals (vdW) confinement not only affects the specific adsorption and diffusion of nuclei on confined substrates but also induces strong coupling to atomic forces at the interface. Using artificial intelligence (AI) assisted density functional theory (DFT) calculations, I study how vdW confinement couples to the atomic motion of monolayer NbSe2 grown between c-plane sapphire and hexagonal boron nitride (h-BN). The calculated force-electronic landscape yields large mechanical forces of +0.070 and -0.04 eV per Angstrom on Nb and Se, respectively, giving rise to a unit-cell interfacial interaction energy up to 2.4 eV, comparable to reported adsorption and diffusion energies on similar substrates. The results indicate that interfacial mechanics may explain the success of confined epitaxy. The findings suggest that tuning interfacial mechanics, and related vdW mechanochemistry, could be a promising route to high-throughput, high-quality materials synthesis.
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Computation and Language

Cognitive Thermometers: Machine Learning and Logical Complexity

Shane Steinert-Threlkeld and Jakub Szymanik

How does the human mind represent semantic categories? Why do natural languages favor certain meanings over others? Prior explanations have relied on logical definability and complexity, but these are highly sensitive to the choice of logical language, rendering some design choices unmotivated. In this article, we propose that machine learning provides a somewhat more agnostic approach to measuring semantic complexity. We review emerging evidence that logic and machine learning often yield converging results on relative complexity and its resulting effects in semantic typology. Where they diverge, learning appears to be a better explanation than logical complexity. We argue that treating machine learning models as “cognitive thermometers” enables a unified approach to complexity that bridges symbolic logic and connectionist AI.
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High Energy Physics (Theory)

Surface defects in $\mathcal{N}=4$ Super Yang-Mills: exact results and holographic bootstrap

Lorenzo Bianchi, Davide Bonomi, Maddalena Ferragatta et al. (+1 more)

We study two-point functions of chiral primary operators in $\mathcal{N}=4$ Super Yang-Mills in the presence of a half-BPS surface defect. Such a defect preserves only the diagonal combination of transverse rotations and of a global U(1) R-symmetry, so that the correlator depends on one additional cross-ratio and splits into sectors of definite angular charge. We solve the superconformal Ward identities and construct the bulk and defect superconformal blocks in all sectors, including the charged ones, which have no analogue for defects preserving transverse rotations. The solution contains a holomorphic sector, which we fix non-perturbatively by mapping it to a chiral algebra correlator. We extend this map to defects breaking transverse rotations, where it requires a redefinition of the modes of the two-dimensional current algebra, and use it to fix the charged sectors as well. We then use the defect dispersion relation to reconstruct the full correlator of the dimension-two chiral primary at leading order at large N and strong coupling. In the charged sectors long multiplets are absent and the answer is conjecturally exact in both N and the coupling; expanding it at weak coupling, we find perfect agreement with known results. From these correlators we extract infinitely many new pieces of defect CFT data. Finally, we reproduce the strong-coupling answer by an independent Witten diagram bootstrap on the rotation-invariant locus.
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All authors Lorenzo Bianchi, Davide Bonomi, Maddalena Ferragatta, Valentina Forini

Computer Vision

LinSlot: Exploiting Linear Representation hypothesis for unsupervised attribute discovery from slot based object representation

Sanket Gandhi, Utkarsh Giri, Varun Subramaniam et al. (+2 more)

This paper studies the problem of learning disentangled representations of objects and their attributes from raw, unstructured image data. Slot-based methods have shown considerable success in unsupervised learning of object representations from images. Block-slot attention-based methods extend this framework to attribute representations by assuming a uniform factorization of object representations into attributes, which may be suboptimal and consequently limit the quality of the learned representations. We therefore investigate a framework for jointly discovering object and attribute representations. Our key contribution is leveraging the Linear Representation Hypothesis (LRH), which postulates that composable concepts can be represented as linearly additive subspaces in slot representations. Based on this insight, we propose a probabilistic model connecting images, slots (objects), and blocks (attributes). We present an architecture that leverages block attention to connect attribute representations to slots and incorporates LRH in both object and attribute representation spaces. This architecture effectively optimizes the Evidence Lower Bound (ELBO) of the proposed graphical model. Our experiments demonstrate (i) effective discovery of disentangled object and attribute representations, (ii) empirical evidence for LRH in slot space, and (iii) the ability to perform image editing owing to the disentangled and interpretable nature of the learned representations. Our experiments on multiple datasets demonstrate improvements in DCI scores over state-of-the-art methods.
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All authors Sanket Gandhi, Utkarsh Giri, Varun Subramaniam, Rohan Paul, Parag Singla

Astrophysics of Galaxies

NGC 4936: abundant multi-phase medium in the central weak X-ray cool core and optically dark H I clouds in the group

Prathamesh Tamhane, Ming Sun, Hao Chen et al. (+6 more)

We present a multiwavelength analysis of NGC 4936, the central galaxy of a weak cool-core group hosting an unusually large cold/warm gas reservoir. NGC 4936 contains $\sim2\times10^8$ M$_\odot$ of molecular gas in a rotating disk of radius $\sim1$ kpc, but no detected H I, with a $3\sigma$ upper limit of $1.13\times10^7$ M$_\odot$ within $\sim2.5$ kpc. The resulting $H_2$/H I mass ratio $>17$ is consistent with a predominantly molecular medium in the high-pressure environments of central galaxies. SOAR imaging and MUSE spectroscopy reveal ionised gas extending to $\sim15$ kpc in a complex filamentary morphology that broadly follows the molecular gas kinematics while extending well beyond the CO disk. Dust filaments similarly extend to $\sim14$ kpc and appear to interact with a companion galaxy located only $\sim2.5$ kpc away in projection. NGC 4936 has a star formation rate of $0.29$ M$_\odot$ yr$^{-1}$, and its AGN shows sub-mm and X-ray variability. We favour atmospheric condensation as the primary origin of the molecular gas, although externally acquired gas may contribute. Our recalculated thermodynamic profiles reach $t_{\rm cool}/t_{\rm ff}\sim25$ in the innermost region, placing the system near the threshold for multiphase condensation. The ongoing interaction may perturb the atmosphere and promote condensation while shaping the morphology and kinematics of the multiphase medium, rather than directly supplying most of the central cold gas. We additionally detect 20 H I structures in the surrounding group environment, with masses of $\sim10^7$–$10^8$ M$_\odot$, including several with no obvious optical counterparts.
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All authors Prathamesh Tamhane, Ming Sun, Hao Chen, Thomas Connor, Megan Donahue, Mark Voit, Mpati Ramatsoku, Kokoro Hosogi, Tim Edge

Systems and Control

Safe Learning of Adaptive Control Policies for Remote Patient Monitoring

Ramanan Tamizholi, Siddharth Chandak, Isha Thapa et al. (+2 more)

Remote Patient Monitoring (RPM) enables continuous observation of patients in their daily environments, improving both health outcomes and quality of life. A key challenge in RPM is determining the optimal monitoring intensity, while balancing patient safety and monitoring costs. This problem is further complicated when system parameters, such as transition probabilities and costs, are initially unknown. We develop a learning-based control framework that estimates these parameters and adapts the monitoring policy in real time. The proposed approach is an online model-based reinforcement learning algorithm tailored to RPM, with patient safety explicitly prioritized during exploration. We provide theoretical guarantees on safety and convergence to the optimal policy. Simulation results show that the algorithm converges to the optimal threshold-based policy, maintains low treatment costs, and reduces the risk of patients reaching critical health states.
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All authors Ramanan Tamizholi, Siddharth Chandak, Isha Thapa, Nicholas Bambos, David Scheinker

Astrophysics of Galaxies

Prevalence of radio Active Galactic Nuclei in galaxy groups since z=3.5 in the COSMOS-Web field

F. Ubertosi, I. Delvecchio, I. Prandoni et al. (+30 more)

Radio active galactic nuclei (AGN) are key tracers of kinetic feedback from supermassive black holes. Although the dependence of their triggering on host stellar mass is well known, the impact of the large-scale environment across cosmic time is poorly understood. We investigate the role of the environment in triggering radio AGN activity, while also studying the dependence on stellar mass ($10\leq\log M_{\ast}\,{\rm [M_{\odot}]}\leq11.4$), radio luminosity ($22\leq\log L_{1.4}\,{\rm [W\,Hz^{-1}]}\leq26$), and redshift ($0.1\leq z \leq 3.5$). We combine the VLA-COSMOS 3 GHz Large Project with the COSMOS-Web galaxy and group catalogs, selecting radio-excess AGN and building radio luminosity functions (RLF) and radio AGN fractions separately for sources in galaxy groups (124 radio AGN) and in the field (405 radio AGN), out of the total of 20203 galaxies and 1678 galaxy groups. We fit the RLF to derive the cosmic evolution of radio AGN in different environments, and we provide a new parametric description of the radio AGN fractions as a function of environment, $M_{\ast}$, $L_{1.4}$, and z. Besides confirming the known positive correlation of radio AGN fraction with host $M_{\ast}$ in both groups and in the field, more importantly we find that the activation of a radio AGN in groups is enhanced relative to the field by a factor of 3–30 in space density and of 2 in radio AGN fraction at fixed stellar mass; the enhancement is also a function of $M_{\ast}$, $L_{1.4}$, and z. Furthermore, in all z bins, the radio AGN fractions peak within $r \leq 0.2R_{200}$. Overall, dense environments enhance radio AGN triggering out to at least z=3.5. We suggest the existence of a possible transition in the dominant triggering mechanism of radio AGN activity around z~1.5, potentially related to the intragroup medium in the core of groups at lower z and to merger and structure growth at earlier cosmic times.
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All authors F. Ubertosi, I. Delvecchio, I. Prandoni, G. Toni, G. Zamorani, E. Daddi, M. Gitti, M. Sargent, A. Traina, C. Spingola, F. Vito, L. Moscardini, G. Gozaliasl, D. Kakkad, W. Wang, S. Sanjaripour, Z. Ghaffari, M. N. Isla Llave, R. M. Samir, G. Peluso, M. Maturi, V. Smolcic, C. Casey, J. Kartaltepe, H. J. McCracken, J. Rhodes, B. Robertson, M. Franco, D. Liu, M. Shuntov, H. Akins, O. Ilbert, A. A. Khostovan

High Energy Physics (Phenomenology)

The Silence of the Dipoles: Accidental Symmetries in Lepton Flavor

Andrea Di Lecce, Majid Ekhterachian, Marko Pesut et al. (+1 more)

Upcoming experiments are set to dramatically improve the search for charged lepton flavor violation, with the sensitivity to the rates of $\mu\to eee$ decay and $\mu N\to eN$ conversion expected to improve by four orders of magnitude in the near future. We study how these measurements reshape our understanding of fundamental interactions and their implications for the Higgs hierarchy problem. We consider the framework of Strongly Interacting Light Higgs with partial compositeness. In generic models of partial compositeness, the existing constraints from $\mu\to e\gamma$ and the electric dipole moment (EDM) of the electron require the scale of Higgs compositeness to be above $\sim\mathcal{O}(100)$ TeV. These mass scales lie beyond the direct reach of the LHC and envisioned future colliders and are comparable to, or higher than, those accessible to future $\mu\to3e$ and $\mu N\to eN$ searches. We show, however, that models where the strongly coupled sector has an accidental $U(3)\times\mathrm{CP}$ or $U(2)\times U(1) \times\mathrm{CP}$ symmetry, broken by the elementary–composite mixings, can substantially relax these constraints. In the $U(3)$ case, these symmetries (1) lead to an accidental alignment of the Yukawa and dipole couplings at leading order, suppressing $\mu\to e\gamma$ and the electron EDM, allowing the compositeness scale to lie in the few-TeV range; (2) are probed by the upcoming $\mu\to eee$ and $\mu N\to eN$ experiments; and (3) provide a direct target for current and future collider experiments. In the $U(2)\times U(1)$ case, $\mu\to e\gamma$ and the electron EDM remain important constraints, while upcoming searches for $\mu\to eee$, $\mu N\to eN$ and flavor-violating $\tau$ decays provide complementary probes. We discuss how these accidental symmetries can arise in the infrared compatibly with the dynamical generation of flavor hierarchies in the ultraviolet.
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All authors Andrea Di Lecce, Majid Ekhterachian, Marko Pesut, Stefan Stelzl

High Energy Physics (Theory)

Carroll-Weyl gauged null strings in AdS

Sarthak Duary and Sourav Maji

We study the Carroll-Weyl gauged null string in the Poincaré patch of $\mathrm{AdS}_D$ and its BRST quantization. In Poincaré coordinates $X^A=(z,x^i)$, the radial conformal Killing vector $K=\partial_z$ becomes homothetic in a suitable conformally related frame. A field-dependent rescaling of the homothetic Hamiltonian constraint then leads to the radial-adapted basis $\mathcal{M}=\frac{1}{2}(P_z^2+P_iP^i)$, $\mathcal{L}=-P_AX'^A$, and $\mathcal{S}=P_z$, with $\mathcal{M}$ invariant along the Carroll-Weyl radial flow. Their modes form a $\mathrm{BMS}_3$ algebra extended by an abelian weight-one current. We classify the central extensions allowed by this residual algebra and find four independent cohomology classes in the $LL$, $LM$, $LS$, and $SS$ channels. We then construct the associated BRST complex, including the ghost pair for the radial Carroll-Weyl constraint. In the canonical highest-weight first-order representation, only the Virasoro-type central extension is realized: $(c_{LL},c_{LM},c_{LS},c_{SS})=(2D-54,0,0,0)$. Cancellation of the corresponding nontrivial BRST cocycle therefore gives $D=27$ in this representation. This differs structurally from the minimal flat Carroll-Weyl theory, where the dilation constraint $X\cdot P$ gives extra anomaly channels.
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High Energy Physics (Theory)

Generalised Gibbs Ensembles from the ODE/IM Correspondence: the Lee–Yang Model

Sujay K. Ashok, Max Downing, Faisal Karimi et al. (+2 more)

We introduce a systematic scheme for constructing the ODE/IM counterpart of generalised Gibbs ensembles, and apply it to the chiral sector of the Lee–Yang conformal field theory. We encode the chemical potentials in a deformation of the cubic oscillator, fixed order by order by requiring that the large-energy WKB period reproduces exactly the driving term of the corresponding thermodynamic Bethe ansatz equation; the subleading WKB periods then yield, as predictions, the deformed eigenvalues of the local conserved charges. We work out the spin-5 ensemble in detail for two states of the model: the ground state, in the module of the primary $\phi$, dual to the deformed cubic oscillator, and the primary of the identity module, dual to the same oscillator supplemented by an apparent singularity, a double pole whose position is fixed by a trivial-monodromy condition. In both cases, the Stokes multiplier obeys the Lee–Yang Y-system, and the deformed eigenvalues match, to the orders checked, an independent conformal-field-theory computation. The Borel resummation of the resulting series for the ground-state energy reproduces the numerical TBA solution over many orders of magnitude in the chemical potential. The scheme relies only on general features of the ODE/IM correspondence and applies to generalised Gibbs ensembles in other integrable models.
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All authors Sujay K. Ashok, Max Downing, Faisal Karimi, Adarsh Sudhakar, Roberto Tateo

Quantum Physics

Nonlinear Feedback in Josephson Circuit Optimization: Application to a Kerr-Reversal JTWPA

Emanuele Palumbo, Alessandro Alocco, Andrea Celotto et al. (+4 more)

Optimizing Josephson-based nonlinear microwave devices is computationally demanding because the straightforward approach requires exploring broad circuit parameter spaces through expensive nonlinear simulations. Josephson Circuits Optimizer addresses this problem by using harmonic balance simulations in two stages: fast linear simulations to select promising circuit configurations according to properties such as impedance and phase matching, followed by nonlinear simulations to optimize their operating conditions. However, pump-induced effects such as impedance renormalization and Kerr-induced modifications of phase matching are not captured during the initial linear stage. We therefore introduce a nonlinear feedback extension that transfers information from the pumped response back to the linear optimization. The approach is investigated using a Josephson traveling-wave parametric amplifier with a reversed-Kerr architecture, whose model is validated against experimental gain measurements. We then evaluate the difference between the linear and pumped response values of a metric based on the input reflection coefficient, while excluding configurations with insufficient third-harmonic suppression. This discrepancy is considered a candidate feedback observable, as it exhibits features similar to the gain landscape, supporting its use in subsequent optimization cycles.
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All authors Emanuele Palumbo, Alessandro Alocco, Andrea Celotto, Luca Fasolo, Bernardo Galvano, Patrizia Livreri, Emanuele Enrico

Quantum Physics

Quantum jumps of sound

Takuma Makihara, Erik Szakiel, Matthew P. Maksymowych et al. (+7 more)

Quantum mechanics predicts that a vibrating object's energy comes in discrete packets, yet no measurement of its position reveals this discreteness. Resolving individual energy levels requires a qualitatively different measurement, one coupling to the resonator's energy rather than its displacement. We use a superconducting qubit dispersively coupled to a nanomechanical resonator to perform repeated quantum nondemolition measurements of the phonon number. An aligned transfer-print technique integrating the qubit and resonator yields a mechanical lifetime of $T_1 = 2.1$ milliseconds and a dispersive shift of $2\chi/2\pi = 328$ kilohertz per phonon. We heralded single-phonon states with 85% fidelity and observed quantum jumps between the resonator's first excited state and ground state. These discontinuous transitions are a striking manifestation of quantum mechanics in a massive, vibrating object.
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All authors Takuma Makihara, Erik Szakiel, Matthew P. Maksymowych, Oliver A. Hitchcock, Kaveh Pezeshki, Rachel G. Gruenke-Freudenstein, Mihir Pendharkar, Shannon P. Harvey, David I. Schuster, Amir H. Safavi-Naeini

Quantum Gases

Quantum simulation of material-specific Hubbard models with alkaline-earth atoms

Henning Schlömer, Reuben R. W. Wang, Bo Xing et al. (+2 more)

A long-term goal of quantum simulation is to faithfully reproduce the low-energy Hamiltonians of correlated quantum materials, establishing a direct connection between solid-state experiment, electronic-structure theory, and programmable many-body systems. Here, we introduce an integrated quantum-simulation architecture based on fermionic alkaline-earth atoms that enables programmable control over the key ingredients of multi-orbital material Hamiltonians. Long-lived clock states encode synthetic orbitals, their differential polarizabilities generate orbital-selective tunneling, and contact interactions provide multi-orbital Hubbard and Hund couplings. Spatially structured coherent driving on the ultra-narrow clock transition further realizes symmetry-selective inter-orbital hybridization, while the clock detuning independently controls orbital energy offsets. In this way, the spatial symmetries of solid-state orbitals can be encoded directly into the effective Hamiltonian, even though the atoms themselves remain in conventional $s$-wave Wannier orbitals of the lowest optical-lattice bands. We demonstrate the resulting integrated control using the four-band low-energy Hamiltonian of the bilayer nickelate La$_3$Ni$_2$O$_7$ as a demanding benchmark. Self-consistent calculations show that the microscopic parameters obtained from first-principles modeling can be reproduced within a single experimentally accessible lattice configuration and independently programmed over substantial parameter ranges. Our results establish a general route for translating material-derived multi-orbital Hamiltonians into programmable ultracold-atom quantum simulators.
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All authors Henning Schlömer, Reuben R. W. Wang, Bo Xing, Susanne F. Yelin, H. R. Sadeghpour

High Energy Physics (Theory)

All-multiplicity completion of maximally supersymmetric gauge amplitudes

Ilmo Sung

We show that the known six-point constraints on four-point amplitudes are sufficient for completion at arbitrary multiplicity in planar, four-dimensional maximally supersymmetric gauge theory. We construct massless tree amplitudes as formal series in the derivative expansion, with the standard supersymmetric Yang-Mills three-point amplitudes, unbroken R-symmetry, and parity invariance of amplitudes with only external scalars, holding the scalar labels fixed. For a positive leading four-point contact coefficient, the even coefficients in the logarithmic parameterization are fixed, while every real sequence of odd coefficients is realized by a completion at all derivative orders. The construction uses the field-theory Kawai-Lewellen-Tye bilinear and normalized matrices of sphere integrals. Exponentiating homogeneous components of their matrix logarithms varies the odd coefficients independently while preserving locality and factorization through the complete massless multiplet. The six-point conditions are therefore necessary and sufficient for such a completion. Higher-multiplicity consistency imposes no further restrictions on these four-point coefficients once the higher-point contact interactions are chosen consistently with the same symmetries and factorization conditions.
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High Energy Physics (Theory)

Reconstructing BPS String Charge Cone in 6d N=(1,0) Supergravity

Yuta Hamada, Hee-Cheol Kim and Kai Xu

The tensor branch of six-dimensional $\mathcal N=(1,0)$ supergravity is characterized by a spectrum of BPS strings charged under the two-form gauge fields. Their charges span a cone in the tensor charge lattice, whose extremal rays are generated by primitive BPS string charges that become tensionless at the boundaries of the tensor moduli space. We develop a systematic procedure, based entirely on effective field theory data, to reconstruct the primitive BPS string generators and thereby determine the complete closed BPS string cone of any 6d $(1,0)$ supergravity theory. The key ingredients are the universal H-string, which allows us to isolate a fixed sector determined by classified LST blocks and gauge anomaly data from the remaining gauge-neutral E-string sector, and a BPS refinement of the Completeness Conjecture that ensures population of the relevant charge rays. We further show that this reconstruction provides new constraints on the low-energy theory and can rule out candidate EFTs that pass all previously known local lattice and anomaly consistency conditions. Separately, for theories admitting geometric tensor bases, we explain how the same reconstruction determines the complete Mori cone of the corresponding Kähler surface.
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Strongly Correlated Electrons

Cooper Instability of a Magnetic Wigner Crystal

Wangqian Miao and Chunli Huang

Recent scanning tunneling microscopy has directly imaged electronic crystals in rhombohedral hexalayer graphene, and magnetotransport measurements suggest that superconductivity and charge-density-wave order emerge from a common spin-valley-polarized ferromagnetic metal at nearby carrier densities. Motivated by these observations, we ask whether collective modes in a magnetic Wigner crystal can mediate pairing in this setting. We address this question by studying the Cooper problem for two electrons in the first conduction band of the Wigner crystal. Unlike conventional phonon-mediated pairing, the collective mode (boson) energies and single-particle (fermion) dispersion are comparable scales controlled by the electron density, leaving no small parameter for an adiabatic expansion. Moreover, because the magnetic Wigner crystal is not time-reversal invariant, the usual Cooper logarithmic divergence in the pairing susceptibility is absent, so the attraction must exceed a finite threshold for pairing to occur. These unusual features motivate a numerical experiment to see whether the crystal's own vibrations can bind electrons. We obtain the crystalline ground state and its collective mode spectrum within Hartree–Fock and time-dependent Hartree–Fock approximation, and derive the electron–phonon Hamiltonian using the quasiboson approximation. Solving the resulting two-electron problem, we find that phonon-mediated attraction exceeds the pairing threshold, with chiral $p$-wave pairing as the leading instability. Within these approximations, we show that collective modes of a Wigner crystal can indeed favor chiral pairing despite broken time-reversal symmetry. Our results provide an encouraging starting point for developing a full many-body theory to study electronic crystallization and superconductivity.
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Soft Condensed Matter

Beyond Dry Flocking: Shape-Dependent Hydrodynamic Alignment

Abhishek Thakur, Taniya Khatun, Soumyadeep Kundu et al. (+3 more)

Flocking results from dynamical alignment among neighbors in a collection of active self-propelling objects. The intervening medium, typically a fluid, however, is not considered to be important for alignment, except for acting as a momentum sink. The flocking system is therefore described as momentum nonconserving "dry" active matter. Here we investigate a confined system of self-propelled Marangoni swimmers where feedback from the fluid medium, which crucially depends on the shape of the swimmers, influences their alignment. Using up to thirty partially camphor-coated triangular paper boats as polar swimmers, we uncover a disorder-to-order transition, and an unusual re-entrant order-to-disorder transition, as functions of camphor concentration and swimmer density, respectively. We reproduce these transitions by formulating a reaction-diffusion model for the camphor field, coupled to the swimmer dynamics, where propulsion forces arise from surface tension gradients. The shape-dependent hydrodynamic interaction discussed here could be central to efficient flocking in living organisms too.
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All authors Abhishek Thakur, Taniya Khatun, Soumyadeep Kundu, Nitin Kumar, P. Parmananda, Anirban Sain

Algebraic Geometry

Embeddings of Derived Categories of Moduli Spaces into Symmetric Powers

Andreas Krug

We give a criterion for the box product of a Fourier–Mukai kernel to induce a fully faithful functor to the derived category of a symmetric quotient stack. This leads to many new examples of embeddings of derived categories of moduli spaces. We study in more detail the case of the moduli space of stable bundles on a curve. Concretely, we identify pieces of the left-orthogonal complement of our embedding, and extend the known semi-orthogonal decomposition of the moduli space of bundles with rank 2 and fixed determinant to the moduli space of bundles with varying determinant.
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High Energy Physics (Theory)

Large Charge Jets in $\mathcal{N}=4$ SYM Energy Correlators

Alba Grassi, Cristoforo Iossa, Luigi Tizzano et al. (+1 more)

We compute the energy-energy correlator in a state created by a heavy canonical operator of scaling dimension $\Delta_H$ in $\mathcal{N}=4$ $SU(N)$ SYM, at fixed $N$ and arbitrary values of the large charge 't Hooft coupling $\lambda \sim \Delta_H g_{\rm YM}^2$. The state created by the canonical operator triggers spontaneous breaking of conformal symmetry and the Higgs mechanism, with squared W-boson masses proportional to $\lambda$. We start with the known finite-coupling result for the underlying four-point function of local operators, perform the detector and Fourier transforms and express the resulting energy-energy correlator as an infinite OPE sum in the source-detector channel, which we then analyze both numerically and analytically. We show that the finite-coupling energy-energy correlator exhibits a hierarchy of distinct physical regimes as a function of $z=(1-\cos\theta)/2$, where $\theta$ is the angle between the detectors. A small-angle vacuum-dominated behavior at $z\ll\lambda^{-1}$ is followed by a non-monotonic medium-induced transient behavior at $\lambda z \sim1$. A large charge jet regime follows, where the energy-energy correlator displays a power-law behavior $\sim1/(\lambda z^3)$ for $\lambda^{-1}\lesssim z \lesssim \lambda^{-1/3}$, before approaching an angle-independent plateau at larger angles.
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All authors Alba Grassi, Cristoforo Iossa, Luigi Tizzano, Alexander Zhiboedov