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Physics

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Monday 8 June

High Energy Physics (Theory)

Anomaly-driven evaporation endpoints of a two-dimensional regular black hole

Damien A. Easson

Spherical reduction of four-dimensional minimally coupled matter yields a two-dimensional theory with dilaton-coupled matter rather than minimally coupled conformal matter. We use this distinction to revisit the backreacted late-time endpoint problem for the regular two-dimensional Bardeen-like black hole considered by Barenboim, Frolov, and Kunstatter. Replacing the Polyakov quantum sector by the dilaton-coupled anomaly model of Fabbri, Farese, and Navarro-Salas (FFN), we derive the corresponding semiclassical field equations and classify the asymptotically allowed late branches at finite radius. For any quiescent finite-radius branch with finite nonzero conformal factor, the late-time mixed equation enforces $J'(r_\infty)=0$, and hence $r_\infty=\sqrt{2}\,\ell$, independently of the local dilaton-anomaly convention. For finite-radius null branches satisfying the stated state-tail assumptions, the ordinary strong-cosmic-censorship-restoring exponential null boundary is excluded. Generic power-law branches $e^{2\rho}\sim v^{-p}$ with $p>1$ are likewise excluded, except for the borderline case $p=2$, which is the only remaining null loophole of this type. In the FFN model, the settled realization of this loophole carries finite affine flux and requires the stronger state-tail decay $s_\phi=O(v^{-2})$. The natural finite-radius outcome is remnant-like, while the surviving null branch is a highly constrained soft-null alternative.
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High Energy Physics (Theory)

Testing F-theory GUTs with the Axiverse

Michael Nee, Mario Reig and Timo Weigand

We show that axions coupled to photons in F-theory Grand Unified Theories (GUTs) satisfy the coupling-to-mass relation $g_{a\gamma}/m_a \leq C\, \frac{\alpha_{\rm em}}{2\pi}\frac{1}{m_\pi f_\pi}$, with $C$ a calculable coefficient. This bound is saturated for the QCD axion with $C = \mathcal{O}(1)$ and holds in field theoretic and perturbative heterotic GUT constructions. In F-theory, topological GUT symmetry breaking by hypercharge flux introduces axion-like particles (ALPs) coupled to photons without coupling to QCD. These ALPs arise from the non-universal holomorphic threshold corrections to the gauge kinetic functions induced by the hypercharge flux. When gauge couplings approximately unify near the string scale, as required in phenomenologically viable models, the shift symmetries of these ALPs are broken by D-instantons whose action is controlled by the size of the threshold corrections to the gauge couplings. Small corrections imply unsuppressed instantons and heavy ALPs. We compute the resulting axion potentials and show that the coupling-to-mass ratio $g_{a\gamma}/m_a$ for every non-universal ALP lies well below the QCD axion prediction. We consider possible loopholes to this result – some of which could lead to $C\gg 1$ – and argue that none of them allows for $g_{a\gamma}/m_a$ to be arbitrarily above the QCD axion prediction within regions of control for the effective action. The bound persists in models with large threshold corrections, where new incomplete GUT multiplets at intermediate energy scales are required. As a result, in the geometric regime, where the $\alpha'$ expansion is under control, no ALP parametrically above the QCD axion band exists. Our results make F-theory GUTs falsifiable: finding an ALP far above the QCD band, for example discovering axion-induced cosmic birefringence, rules out F-theory GUTs in regimes of control of the effective theory.
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High Energy Astrophysical Phenomena

The Curious Case of PHL 1811: Heavy Obscuration Versus Intrinsic X-ray Weakness

B. Luo, Xiaolei Chen, Jian Huang et al. (+2 more)

We present a systematic X-ray analysis of the narrow-line Type 1 quasar PHL 1811, which has long been regarded as the prototype of intrinsically X-ray weak quasars. A critical breakthrough came with the first detection of a bright X-ray flare from this source by the Einstein Probe (EP) in 2024. We utilize archival X-ray observations spanning 2001-2024, including the post-flare EP and Swift data. We confirm that PHL 1811 shows X-ray weakness factors $f_{\rm weak} \approx 23$-179 across all epochs before 2024. The 2024 EP flare marks the first detection of an X-ray nominal state with $f_{\rm weak} \approx 0.63$, followed by a rapid flux decline. We identify three key observational signatures that strongly support heavy obscuration: (1) a significant hard X-ray excess above $\approx5$ keV in the 2015 XMM-Newton spectrum; (2) relatively flat spectral shapes in two Swift observations; and (3) transitions between X-ray nominal and multiple X-ray weak states without corresponding optical/infrared variability, consistent with expectations from obscuration by a clumpy dust-free absorber. Fitting with a partial-covering obscuration model reproduces all multi-epoch spectra well. The observed steep spectra are dominated by a small leaked/scattered fraction of the intrinsic continuum, and variability is driven by changes in the leakage fraction and column density. Our results strongly favor the scenario where PHL 1811 is obscured by a radiatively driven accretion-disk wind from super-Eddington accretion, unifying PHL 1811 with the broader population of super-Eddington accreting AGNs under a single obscuration framework.
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All authors B. Luo, Xiaolei Chen, Jian Huang, W. N. Brandt, Qingling Ni

High Energy Physics (Theory)

Where is tree-level heterotic string theory?

Mathieu Boisvert, Waltraut Knop and Leonardo Rastelli

We continue the tree-level S-matrix bootstrap program for quantum gravity, now in ten-dimensional theories with half-maximal supersymmetry. This setting includes the heterotic string and allows us to test whether the string-like structures found in the maximally supersymmetric bootstrap persist with less supersymmetry and in non-planar gauge sectors. Imposing analyticity, crossing symmetry, unitarity, and Regge boundedness, we constraint weakly coupled UV completions of supergravity and super Yang-Mills. In the gravitational sector, much of the boundary of the allowed region is explained by extremal amplitudes supported on a single linear Regge trajectory, or by convex combinations of such amplitudes. In the gluon sector, the non-planar problem reveals a tension between representation-channel positivity and the trace decomposition of the EFT data, obstructing a direct normalization by $G$ or $g_{\rm YM}$; a coupled gluon/graviton bootstrap may be necessary to directly constrain the relative strength of gauge and gravitational interactions. Overall, our results support the emergence of linear Regge trajectories as a robust feature of the tree-level quantum-gravity bootstrap.
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Earth and Planetary Astrophysics

Planet or brown dwarf? Constraints on the formation of H-type objects in IC348

Richard J. Parker and Catarina Alves de Oliveira

The formation mechanism(s) of substellar objects, such as brown dwarfs and free-floating planets, remains an ongoing puzzle in stellar and planetary physics. Recent observational and theoretical work points towards a star-like origin for brown dwarfs, though several authors posit that they could form like planets in a circumstellar disc, and then subsequently be ejected into a star-forming region or the Galactic field. Recently, JWST observations have discovered nine substellar objects in the IC348 star-forming region with a spectral absorption feature at 3.4$\mu$m from an unidentified aliphatic hydrocarbon, detected for the first time in planetary atmospheres outside of the Solar System. It is unclear whether these hydrocarbon absorption features in these 'H-type' objects indicate a different formation mechanism compared to more massive brown dwarfs. We quantify the spatial distribution of these objects and find they are indistinguishable from the spatial distribution of stars and other brown dwarfs in IC348. We use N-body simulations to test whether the H-type objects could have formed as planets in circumstellar discs and then been dynamically ejected by stellar fly-bys. We show that a similar number of free-floating planets could be produced if those planets initially resided at ~5au from their host stars. However, these free-floating planets have a much more dispersed spatial distribution than the stars and brown dwarfs, inconsistent with the spatial distribution of the H-type objects in IC348. We therefore conclude that the H-type objects are unlikely to have a planetary-like origin.
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High Energy Physics (Theory)

Resonance and Differential Reduction of Feynman Integrals

Ruth Britto, Thomas W. Grimm and Arno Hoefnagels

Feynman integrals may be viewed as generalized hypergeometric functions, and specifically as solutions of GKZ systems of partial differential equations that typically exhibit resonance. Resonance is a type of non-genericity implying reducibility to subsystems. We use this resonance to construct reduction operators, which are differential operators that can contract edges of Feynman graphs. Correspondingly, their action is naturally compatible with cuts of Feynman graphs. Reduction operators may be used to close the system of differential equations for a given integral. The remaining GKZ data lead to algebraic relations identifying a smaller system that is fully reduced to master integrals. We develop the construction for one-loop, sunrise and banana graphs and discuss restrictions to physical kinematics. While reduction operators can generally shift both propagator powers and spacetime dimension, certain combinations isolate a pure dimension shift together with contraction of a chosen edge.
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High Energy Physics (Theory)

Zeta Functions and the Superstring

Grant N. Remmen

The superstring amplitude's Mellin transform in energy is computed at fixed momentum transfer. In the forward limit, it is shown that this transformed amplitude reduces to the Riemann zeta function, while for $t\neq 0$ it represents a deformation of $\zeta$. This object exhibits remarkable mathematical properties as a result of physical attributes of the string amplitude. For integer subtractions, the dispersion relation defined by the Mellin transform yields the effective field theory expansion of the string amplitude order by order in $s$ at finite $t$, for which a new closed-form expression is derived.
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High Energy Physics (Phenomenology)

Too Heavy to Hide: Gamma-Ray Constraints on Annihilating Dark Matter beyond Unitarity

Abhishek Dubey, Deep Jyoti Das and Akash Kumar Saha

The measurement of high energy diffuse gamma rays by various ground-based air shower detectors have opened a new chapter for high energy particle physics and astrophysics. The broad range of viable dark matter candidates motivates extending indirect searches to heavier dark matter masses, opening new opportunities to uncover the nature of dark matter. If dark matter is composite rather than point-like, then the thermal unitarity bound can be relaxed, opening up the possibility of dark matter masses far beyond the electroweak scale. We perform a model agnostic search for heavy annihilating dark matter using the gamma-ray measurements and upper limits from Tibet AS$_\gamma$, LHAASO, KASCADE-Grande, Pierre Auger Observatory, and Telescope Array. These highest energy datasets enable us to probe new regions of parameter space and set world-leading limits on the annihilation cross sections for dark matter masses $10^5$–$10^{12}$ GeV. Our work highlights the power of high energy gamma-ray datasets in discovering heavy dark matter signatures in the near future.
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Astrophysics of Galaxies

Discovery and Spectroscopic Characterization of a Distant, Compact Milky Way Satellite in Gemini

K. Overdeck, W. Cerny, C. Y. Tan et al. (+27 more)

We present the discovery of a compact Milky Way satellite in the constellation of Gemini. This system was discovered by cross-matching detections from two independent search algorithms applied to Blanco/DECam data from the third data release of the DECam Local Volume Exploration survey (DELVE DR3), and confirmed with deeper imaging from Gemini/GMOS-N. Based on these data, we determine that the system is an ultra-faint ($M_V = -2.1^{+0.4}_{-0.6}$), compact ($r_{1/2} = 8.6^{+1.4}_{-1.2}$ pc) system located at a heliocentric distance of $120^{+7}_{-6}$ kpc. These physical properties place the system in the regime of ambiguous, ultra-faint compact Milky Way halo satellites that cannot be confidently classified as dwarf galaxies or star clusters from morphology alone; we therefore name the system DELVE 8/Gemini I. From medium-resolution Keck/DEIMOS spectroscopy, we securely identify four members including two blue horizontal branch stars, confirming the system as a bound satellite moving at a mean radial velocity of $v_{\rm hel} = -82.7^{+3.7}_{-3.9} {\rm km\,s}^{-1}$. We also use these spectra to place an upper limit of $\rm [Fe/H] \lesssim -2.5$ on the metallicity of DELVE 8/Gemini I's brightest star, supporting the classification of the system as either an ancient star cluster or ultra-faint dwarf galaxy. The discovery of faint, distant systems similar to DELVE 8/Gemini I is expected to become more common with upcoming surveys.
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All authors K. Overdeck, W. Cerny, C. Y. Tan, C. E. Martínez-Vázquez, A. B. Pace, J. A. Sharp, A. Drlica-Wagner, M. Geha, D. J. Sand, J. A. Carballo-Bello, Y. Choi, D. Crnojevíc, P. S. Ferguson, M. Hirschauer, D. J. James, N. Kallivayalil, G. Limberg, P. Massana, S. Mau, G. E. Medina, B. Mutlu-Pakdil, M. Navabi, D. L. Nidever, N. E. D. Noël, A. Pai, A. H. Riley, J. D. Sakowska, L. Santana-Silva, G. S. Stringfellow, A. K. Vivas

Instrumentation and Methods for Astrophysics

Flux Cube Reconstruction from Slitless Spectroscopy

M. Griggio, R. E. Ryan Jr., N. Pirzkal et al. (+19 more)

Slitless spectroscopy enables efficient, large-area surveys without target pre-selection, yet it faces challenges from source blending, higher noise, and lost spatial-spectral information. We present an advanced, non-parametric, data-driven algorithm that leverages multiple dispersion angles to reconstruct three-dimensional flux distributions, providing low-resolution Integral Field Unit (IFU) capabilities from slitless data. By treating each pixel as an independent element, our method naturally handles source confusion without requiring prior assumptions regarding redshifts, templates, or model libraries. We validate the algorithm using simulated Roman Space Telescope wide-field slitless spectroscopy images that are equivalent to what is expected from the High-Latitude Time-Domain Survey. First, we demonstrate that a host-galaxy model reconstructed from multiple dispersion angles can be used to accurately subtract host light from a transient, recovering a Type Ia supernova spectrum with minimal bias. Second, we showcase a high-fidelity flux-cube reconstruction of a complex galaxy, successfully measuring the redshift and recovering continuum, emission, and absorption features. This approach highlights the potential of multi-dispersion-angle slitless data to provide spatially resolved spectral information in a non-parametric way, which is traditionally accessible only with integral field spectroscopy, opening a new window into large, unbiased, and spatially-resolved studies of galaxy evolution.
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All authors M. Griggio, R. E. Ryan Jr., N. Pirzkal, T. L. Astraatmadja, S. Casertano, S. Perlmutter, D. Rubin, G. Aldering, J. M. DerKacy, O. D. Fox, A. S. Fruchter, L. Galbany, R. Hounsell, A. M. Isaacs, P. L. Kelly, R. S. Kessler, B. M. Rose, J. Roychowdhury, M. Sako, D. M. Scolnic, L.-G. Strolger, the Roman Supernova Cosmology Project Infrastructure Team

Earth and Planetary Astrophysics

Stellar Obliquities of Young Systems, Atmospheres Undergoing Contraction and Escape (SOYSAUCE) II: a 135 Myr planet on an aligned orbit with transit timing variations

Madyson G. Barber, Andrew W. Mann, Sydney Vach et al. (+16 more)

Young planets (<1 Gyr) provide opportunities to directly probe planet formation and evolution processes in action. However, due to heightened stellar activity, there is a lack of known transiting planets in adolescence (~100-500 Myr). Here we present the validation of TIC 150070085 b, a 3.6 R_E planet on a 10.47 day orbit, and report the candidate TIC 150070085 c, a 3.0 R_E planet on a 15.90 day orbit. While we are unable to validate the second signal, the proximity to mean motion resonance (3:2) and transit timing variations observed in the transits of TIC 150070085 b strongly suggest the signal is planetary. We confirm the host star as a member of Alessi 84 and combine the group's CMD, rotation, and variability properties to update the age to 135 +/- 10 Myr. We additionally use MAROON-X to observe the Rossiter-McLaughlin signal of TIC 150070085 b and measure the sky projected obliquity angle ($\lambda$). We find TIC 150070085 b is consistent with a near-aligned orbit with its host star (|$\lambda$| = 18 +/- 12$^\circ$), in line with similarly aged transiting planets with measured $\lambda$ values. Continued discovery and characterization of planets in this age regime are vital to link planetary infancy (<50 Myr) and maturity (>1 Gyr).
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All authors Madyson G. Barber, Andrew W. Mann, Sydney Vach, Leah J. Boff, Andrew W. Boyle, Andrew Vanderburg, Adam L. Kraus, Benjamin M. Tofflemire, Marshall C. Johnson, Allyson Bieryla, David W. Latham, Karen A. Collins, Steve B. Howell, Richard P. Schwarz, Gregorg Srdoc, Francis P. Wilkin, Felipe Murgas, Enric Palle, Chris Stockdale

High Energy Physics (Theory)

Maximal Transcendentality of the Double-Scaled PCM

Evgeny Sobko

We prove, to all orders, maximal transcendentality of the strongly coupled large-N Principal Chiral Model in the double-scaling regime introduced in our earlier work. We also prove that, after a natural shift of the coupling constant, the coefficients of the vacuum-energy expansion are expressed purely as polynomials in odd zeta values with rational coefficients. The first 35 explicitly computed orders reveal further number-theoretic regularities, pointing to hidden structure beyond maximal transcendentality.
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Quantum Physics

Magic and entanglement in 1+1-dimensional SU(2) lattice gauge theory

Raghav G. Jha, Goksu C. Toga, Jaber I. Taher et al. (+2 more)

Entanglement and non-stabilizerness (magic) quantify two distinct departures of quantum systems from classical description: the former measures non-local correlations, while the latter measures the deviation from stabilizer states that can be efficiently simulated classically. Understanding magic in physically relevant quantum field theories is essential for identifying where quantum advantage may be realized in the early fault-tolerant quantum computing era. We calculate the gauge-invariant entanglement entropy and stabilizer Rényi entropy of the ground state of the (1+1)-dimensional SU(2) lattice gauge theory formulated in a dressed-site basis that enforces Gauss's law exactly. Using tensor networks, we obtain results for system sizes up to $L=100$ (300 qubits). We find a crossover denoted by $g_{\star}$ where the ground state passes from a more magic-rich regime into a regime with less magic; this is also tracked by the sharpest change of both the entanglement entropy and lattice particle density. Our large-scale study of non-stabilizerness and entanglement entropy in a non-Abelian lattice gauge theory with matter provides new insight into the interplay of magic and entanglement in gauge theories, both of which are relevant for classical and early fault-tolerant quantum simulations.
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All authors Raghav G. Jha, Goksu C. Toga, Jaber I. Taher, Bojko N. Bakalov, Alexander F. Kemper

Astrophysics of Galaxies

Through the Veil: Ly$\alpha$ Illuminates the Host Galaxies of Little Red Dots

Zhiyuan Ji, Yang Sun, Mauro Giavalisco et al. (+5 more)

Little Red Dots (LRDs) are enigmatic, compact red sources ubiquitous in JWST deep fields whose physical nature remains elusive. As one of the most sensitive tracers of neutral hydrogen in galaxy environments, Ly$\alpha$ is uniquely positioned to probe the gaseous structures proposed to explain LRDs' unusual properties. We present a systematic study of Ly$\alpha$ emission in LRDs, using a sample of 110 spectroscopically confirmed LRDs at $z \geq 4$ from the A. de Graaff et al. (2025) catalog, all with NIRSpec/PRISM coverage of the Ly$\alpha$ line. We detect Ly$\alpha$ at signal-to-noise S/N $\geq$ 3 in 32 LRDs, finding Ly$\alpha$ luminosities and the distribution of rest-frame equivalent widths consistent with normal star-forming galaxies at comparable redshifts. Yet the Ly$\alpha$/H$\alpha$ ratios fall systematically below those of star-forming galaxies, and the Ly$\alpha$ luminosity tracks [O III] luminosity more closely than [O III] equivalent width, together suggesting that Ly$\alpha$ is primarily associated with the host-scale component rather than the compact component responsible for the broad Balmer lines and red continuum. For 13 LRDs at $z \gtrsim 5.5$, we construct continuum-subtracted Ly$\alpha$ maps using broadband imaging from HST/ACS or JWST/NIRCam, revealing spatially extended, asymmetric, and often offset emission relative to the rest-optical light, consistent with resonant scattering through clumpy, anisotropic gas commonly observed in high-redshift Ly$\alpha$ emitters. These results support a two-component picture in which the compact rest-optical source is embedded within a more extended host-galaxy environment whose interstellar and circumgalactic gas shapes Ly$\alpha$ escape and spatial redistribution. Ly$\alpha$ opens a new window into the relation between the compact red component, the host galaxy, and the surrounding gas in LRDs.
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All authors Zhiyuan Ji, Yang Sun, Mauro Giavalisco, Anna de Graaff, Christina C. Williams, Yongda Zhu, George H. Rieke, Marcia Rieke

High Energy Physics (Theory)

Calling the Brane Next Door: The Kaluza-Klein Tower as a Gravitational Information Channel

Karim Benakli

Could two worlds localised on neighbouring branes communicate through gravity alone? We investigate this question in a minimal higher-dimensional framework in which Standard Model fields are confined to our brane while gravity propagates through the bulk. From the brane-to-brane graviton propagator we derive the retarded transfer kernel of the inter-brane link and identify the transition from evanescent to propagating Kaluza-Klein modes. The central idea is to give the Kaluza-Klein tower a new role: not only as a spectrum of massive gravitational states, but as a set of communication carriers. Below the first KK threshold the channel is effectively four-dimensional and is mediated only by the massless graviton. Above threshold, massive KK modes open as additional propagating subchannels, and information may be encoded in their occupation pattern, relative phases, and arrival-time structure as well as in ordinary signal variables. The compactification determines the KK masses, wavefunctions, brane overlap factors, and propagation phases, which together define a multi-input multi-output (MIMO) channel matrix. In the resolved-mode limit, the tower yields approximate parallel subchannels, to which standard information-theoretic notions such as capacity bounds, water-filling, effective rank, and sparse occupancy codes apply. The production and detection of such signals are highly model-dependent and not assumed to be feasible with known technology. Nevertheless, the channel structure is well defined: a neighbouring brane-world could be separated from us by a microscopic distance in the compact space while remaining hidden because the only shared interaction is gravity. The first observable signature may not be a deliberate message, but the spectral and modal structure of the Kaluza-Klein tower itself, revealing partial information about the geometry of a nearby hidden world.
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High Energy Physics (Phenomenology)

Radio Emission from High-Frequency Gravitational Wave Point Sources

Ethan Baker and Hongwan Liu

High-frequency gravitational waves (HFGWs) in the MHz to GHz regime can convert into radio photons in the presence of astrophysical magnetic fields through the inverse Gertsenshtein effect. We show that existing radio telescopes like CHIME and FAST are excellent tools for detecting HFGW sources, significantly outperforming many existing experiments at detecting primordial black hole (PBH) mergers, the most realistic sources of transient HFGWs. Radio telescopes are also uniquely sensitive to sources of monochromatic HFGW emission, such as ultralight boson clouds formed through superradiance around PBHs, and are likely to have excellent sensitivity to generic sources of detectable HFGWs.
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Quantum Physics

JGRA: Jacobian Geometry Robustness Assessment in NISQ Noise-Aware Quantum Neural Networks

Gianluca Scanu, Luca Barletta and Stefano Rini

The NISQ era places stringent constraints on quantum computation, where noise and decoherence fundamentally limit performance. In classical deep learning, model robustness and resilience to perturbations are well studied: deep neural networks (DNNs) maintain high performance despite pruning, noise injection, and structural perturbations due to inherent redundancy in their representations. A central challenge in quantum machine learning is to transfer this notion of robustness to quantum neural networks (QNNs) under realistic NISQ noise. While classical deep learning exhibits robustness through structural redundancy, analogous principles for QNNs remain underdeveloped. We propose JGRA: a framework for assessing robustness in noise-aware QNNs via Jacobian geometry, capturing model sensitivity to parameter perturbations induced by noise. Our method includes entropy-matched noise calibration, noise-aware training, and noise-conditioned Jacobian extraction, yielding geometric descriptors that link clean-regime structure to noisy inference behaviour. We also empirically demonstrate that these descriptors encode predictive information about robustness under unseen noise.
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Fluid Dynamics

Geometry-Aware Anisotropic Boundary Correction for Aerodynamic Simulation

Xin Zhang, Yipeng Huang, Shu Jiang et al. (+2 more)

Aerodynamic simulation is a key component of engineering shape design, where core quantities such as the surface pressure coefficient strongly depend on flow dynamics near solid boundaries. Neural operators provide an efficient alternative to expensive Computational Fluid Dynamics (CFD) solvers. However, conventional methods treat the boundary region isotropically, failing to account for the distinct physical behaviors along the boundaries. In reality, the aerodynamic process exhibits anisotropy: along the tangential direction, flow propagates along the wall; along the normal direction, physical quantities are constrained by the wall. To explicitly model the distinct physical behaviors, we propose GeoABC, a geometry-conditioned anisotropic boundary correction framework. GeoABC leverages the boundary geometries to introduce direction-aware boundary correction into the intermediate representations of neural operators, transforming boundary geometry from static input features into a structural prior that modulates physical prediction. On 2D airfoil and 3D car tasks, GeoABC consistently adapts to multiple neural operator backbones, reducing near-boundary relative $L_2$ error by $\sim$38% on average, narrowing the structural near-wall gap shared by mainstream neural operators, and advancing neural operators toward high-fidelity aerodynamic simulation.
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All authors Xin Zhang, Yipeng Huang, Shu Jiang, Zhenzhong Wang, Min Jiang

Medical Physics · Cross-listed from q-bio.QM

Adjusted trajectory of medication exposure taking into account the periodicity of dispensations and the number of dispensed packs and comparative analysis on EFEMERIS database

Cécile Chouquet, Anna-Belle Beau, Christine Damase-Michel et al. (+3 more)

We presented an adjustment method for the calculation of medication exposure trajectories based on the number of dispensed packs and the type of dispensations (occasional or regular). A comparative study based on the EFEMERIS data was carried out using three different scenarios of trajectory calculation depending on whether or not the number of packs and the periodicity of medication dispensations were taken into account. The impact of the scenario was highlighted using global indicators on the number of Define-Daily Dose (DDD) on all women exposed; the study of changes in individual trajectories from one scenario to another was carried out; we also compared the results of a clustering into four groups. If 65% of the trajectories remained unchanged, we could observe on the rest significant changes in number of DDD and/or on individual exposure profile. We observed 4% of trajectories that were attributed to a different cluster, and the clustering was of better quality with the adjustment method. Depending on the study context, an impact on cluster distribution could be observed for some maternal characteristics and neonatal outcomes. This was the case for a higher occurrence of neonatal pathology for neonates from mothers belonging to the cluster with high doses of psychotropics, thus reinforcing the conclusions of previous studies of a link between high exposure to psychotropic medications and presence of pathology for the newborn.
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All authors Cécile Chouquet, Anna-Belle Beau, Christine Damase-Michel, David Jeauneau, Isabelle Lacroix, Sabine Mercier

Nuclear Theory · Cross-listed from cs.LG

Integrating Out, Twice:The Open-System Case That Neural-Network Ensemble Theory Is Missing

Jin Lei

Averaging a neural network over its random parameters and marginalizing a Gaussian sector are the same operation, the Schur complement of the eliminated block, and when that block is closed it returns a covariance and its inverse. That is all a network ensemble produces, the closed case. The open case is missing, and nuclear reaction theory has it worked out. Projecting a scattering problem onto a chosen set of channels, with the rest carrying probability irreversibly to a continuum, leaves a non-Hermitian effective generator that conserves and itemizes exactly what it loses: the nuclear optical model and its generalized optical theorem. I set the two cases side by side using only the moments of a distribution, the algebra of Gaussians, and block inversion, no field theory, and give the closed-case dictionary in full: the neural tangent kernel is the Fisher sensitivity kernel, the infinite-width Gaussian limit is the Gaussian-process emulator, and the lazy-to-feature transition is the validity boundary of a reduced-basis emulator. I then test the open export on a truncated attention map, a token-level transfer operator, and a sparse expert router, and report a mostly negative result. The conserved flux ledger ports wherever openness is genuinely present, but its distinctive content is absent, an artifact of the chosen partition, or pinned near a floor by the training objective, and the operationally useful uncertainty turns out to be epistemic, living in the closed half of the correspondence, not the open one. The negative has a structural reason this note makes precise: the open case needs an eliminated sector with a continuous spectrum and wave-like, not relaxational, dynamics, which mainstream learning's finite or dissipative objects do not supply. This is a note, not a result; its main finding is that negative one, and its value is the map that locates it.
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Materials Science

Anatomy of fast current-induced skyrmion motion in synthetic antiferromagnets

W. C. Chen, H. X. Yang and X. F. Zhang

The high mobility of current-driven skyrmions in synthetic antiferromagnets (SAFs) is widely explained by the macroscopic suppression of the skyrmion Hall effect through gyrotropic force compensation. This established view, however, overlooks a concurrent and significant reduction in the Gilbert damping parameter {\alpha}, a key factor in the Thiele equation governing skyrmion velocity. Here, we show that this damping attenuation originates from a reconfigured magnon-electron scattering landscape. Using a microscopic s-d model, we demonstrate that the strong antiferromagnetic interlayer Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange coupling in SAFs increases the magnonic gap of skyrmion collective modes, thereby suppressing the thermal magnon population and, consequently, the magnon-electron scattering rate that dominates damping in metallic ferromagnets. Our work establishes a dual-mechanism framework to fully explain the superior kinetics of SAF skyrmions: the macroscopic topological effect rectifies the motion direction, while the microscopic dissipation mechanism reduces the drag. This synergy enables high-speed and efficient motion, providing a fundamental elucidation of the enhanced mobility reported in recent studies such as the work by Pham et al. [Science 384, 307-312 (2024)].
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Quantum Physics

Disjoint Bell measurements enable near-projective GHZ certification

Hyunho Cha and Jungwoo Lee

Certifying multipartite entangled states is a basic task in quantum information processing, but the achievable copy complexity depends crucially on the measurements available to the verifier. The strongest possible certification measurement for a known pure target state $|\psi\rangle$ is the two-outcome projector $\{|\psi\rangle\langle\psi|,\mathsf{I}-|\psi\rangle\langle\psi|\}$, which is copy-optimal but often experimentally unrealistic or outside the intended measurement model. In this work, we introduce BM-Cert, a single-copy verification protocol for the $n$-qubit Greenberger–Horne–Zeilinger (GHZ) state using only disjoint two-qubit Bell-basis measurements, together with one single-qubit $X$-basis measurement when $n$ is odd. Surprisingly, a simple combinatorial effect yields perfect completeness and a verification spectral gap $\nu_\mathrm{BM}(n)=1-O(1/n)$, so our depth-2 protocol already approaches the ideal projective verification asymptotically as $n$ grows. This contrasts with local Pauli GHZ verification, whose optimal spectral gap remains bounded away from $1$. Thus, allowing only two-qubit entangling measurements on disjoint pairs is enough to achieve asymptotically ideal projective certification. The same Bell-matching outcomes also yield BM-Fid, an unbiased estimator of the GHZ fidelity whose leading Hoeffding coefficient in the sample complexity tends to the ideal value achieved by direct projection. For the open-boundary linear nearest neighbor setting, we further introduce Brick-Cert, a disjoint 2-local certification protocol whose spectral gap $4/5$ is optimal within that restricted architecture.
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General Relativity and Quantum Cosmology

Geometric Matching of Local Static Regions in Cosmological Spacetimes with an Evolving Lapse

Seokcheon Lee

The generalized cosmological time (GCT) framework introduces a modified lapse function, N(t)\propto a^{b/4}, as a geometric extension of the standard FLRW description. Like other departures from $\Lambda$CDM, such constructions must remain compatible with the observed stability of local gravitational and laboratory physics. In scalar–tensor theories, this compatibility is usually achieved through dynamical screening mechanisms that suppress additional degrees of freedom in dense environments. In this work, we examine whether a locally static spacetime region can be consistently embedded within a cosmological background described by a time-dependent lapse. By embedding a static Schwarzschild interior into an expanding GCT–FLRW exterior, the Israel junction conditions are used to determine the class of background expansions that admit such a matching in the absence of a thin shell. The continuity of the extrinsic curvature yields a Friedmann-type relation that coincides with the GCT background equations of motion. This relation should be interpreted not as a new dynamical equation, but as a geometric consistency condition (GCC) associated with the matching of the two spacetime regions. In this sense, the junction does not introduce new dynamics, but provides a GCC under which a region with fixed local clocks can be embedded in a cosmological spacetime with an evolving lapse. Therefore, the analysis clarifies how locally static gravitational systems can remain compatible with a cosmological time normalization that differs from that of local proper time while preserving the standard description of local physics.
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High Energy Physics (Phenomenology)

Testing Supersymmetric Hidden Sectors with Long-Baseline Atom Interferometers

Oem Trivedi

Atomic interferometry provides a sensitive near Earth probe of high energy physics through precision measurements of quantum phase. In this Letter, we point out that MAGIS and AION like long-baseline atom interferometers can also be used to test supersymmetric hidden sectors, if these sectors contain ultralight moduli, dilatons or hidden scalars that induce coherent phase oscillations. In such a setup, the measured atomic phase does not only constrain an effective phenomenological scalar coupling. It can be related to derivatives of supersymmetric gauge kinetic functions, Kähler metrics, Yukawa couplings, Higgs sector parameters and the QCD scale along light hidden sector directions. We derive the mapping from a generic SUSY/SUGRA modulus to the effective atom interferometric coupling, and show that future phase sensitivities may probe very small visible sector admixtures of otherwise hidden fields. This identifies MAGIS/AION type experiments as non-collider probes of supersymmetric and string-motivated infrared relics, complementary to gravitational wave, astrophysical and collider searches.
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Strongly Correlated Electrons

Topological Triplons in the Pinwheel Valence Bond Solid on the Kagome Lattice

Laura Calonge-Martínez, Peng Rao, Frédéric Mila et al. (+1 more)

We investigate the triplon excitations of the pinwheel valence-bond-solid phase on the deformed kagome lattice compound Rb2Cu3SnF12. Using bond-operator mean-field theory, we compute the triplon band structure, dynamical structure factor, Berry curvatures and the associated thermal Hall response. We show that the presence of Dzyaloshinskii-Moriya interactions and an external magnetic field are key for endowing triplon bands with nontrivial Chern numbers. We find good qualitative agreement of the low-energy dynamical structure factor with neutron-scattering experiments. An applied magnetic field can isolate the lowest triplon Chern band leading to a tunable thermal Hall conductivity for accessible temperature and field regimes. Our results establish the deformed kagome pinwheel valence-bond solid as a promising platform for topological triplon physics and for observing the associated thermal Hall effect.
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All authors Laura Calonge-Martínez, Peng Rao, Frédéric Mila, Johannes Knolle

General Relativity and Quantum Cosmology

Limits of the Rastall–Einstein Equivalence: Matter-Action Compatibility, FLRW Dynamics, and Exceptional Sectors

José A. C. Nogales, Karen-Luz Burgoa Rosso and Marcelo H. Alvarenga

A regular Rastall metric equation can be written exactly as an Einstein equation with a conserved algebraic source. We examine whether this source redefinition also preserves a specified local matter-action class. For an isentropic barotropic fluid, keeping the particle-density variable and its conserved current fixed gives the compatibility condition $3n\rho_{,nn}-\rho_{,n}=0$, whose non-Einstein solutions are $\rho(n)=\rho_\Lambda+C n^{4/3}$. For a minimally coupled first-derivative scalar field with the same field and kinetic variable, preservation of the local $\mathcal L_\phi(X,\phi)$ class gives $X\mathcal L_{\phi,XX}-\mathcal L_{\phi,X}=0$, and hence $\mathcal L_\phi=\frac12\mathcal A(\phi)X^2+\mathcal B(\phi)$. These are off-shell functional compatibility tests within restricted continuum action classes; they do not by themselves establish equivalence of full solution spaces or observables. Throughout the analysis, $T_{\mu\nu}$ denotes the physical energy–momentum tensor of the specified matter model. Its Einstein-form algebraic image is $\Theta_{\mu\nu}[T]=T_{\mu\nu}-\alpha g_{\mu\nu}T$. We also complete the dictionary between two Ricci–trace parametrizations, including the coupling, and state a limited on-shell variational obstruction with its exceptions. The analysis includes Poisson-level weak-field matching for an operational rest-mass density, the singular FLRW branch $D(w)=0$, a classification of exceptional parameter sectors, and a comparison of Rastall gravity with standard unimodular gravity and nonconservative trace-free completions. The regular Rastall metric equation is therefore algebraically equivalent to an Einstein equation with a redefined source; equivalence of completed matter–gravity models is a separate, stronger requirement.
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Astrophysics of Galaxies

Satellite compaction pathways: environmental drivers shaping dwarf galaxy corpulence in the TNG50 simulation

Abhner P. De Almeida, Gary A. Mamon and Gastão B. Lima Neto

We explore the physical mechanisms driving dwarf galaxy corpulence, focusing on those that end up as compact satellites. We select dwarf galaxies at $z=0$ with $\log(M_\star/{\rm M}_\odot)$ between 8.4 and 9.2 from the TNG50 hydrodynamical simulation after excluding systems flagged as potentially spurious. Compact dwarfs are defined according to the $z=0$ size-mass relation as those on the lower envelope of its main branch or on its lower-size secondary branch, while "Normal" lie on the main branch spine. We identify two robust compaction pathways and a third, more tentative, channel: 1) Compact satellites that remain rich in dark matter (DM) inhabit poorer environments having fewer mergers, favouring the accretion of lower-angular-momentum gas. This allows gas inflows that drive concentrated inner star formation and compaction, as previously found for centrals. 2) Most DM-poor satellites (which typically end up red and metal-rich for their stellar mass) undergo compaction mainly caused by tidal stripping of outer stars. Their compaction is faster when gas is present, by at least 15 per cent after correcting for the stronger tidal field. 3) For most of our few very metal-rich DM-poor Compact satellites, the major compaction phase begins with a starburst driven by ram pressure compression near first pericentre, even if much of the compaction often occurs during subsequent tidal stripping. As a result, compact dwarf satellites in TNG50 arise through distinct pathways. We discuss how numerical effects can affect this conclusion.
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Solar and Stellar Astrophysics

ALMA measurements of mass loss and wind clumping in the massive stars of the Arches cluster

James P. Perry, Raman K. Prinja, Danielle M. Fenech et al. (+1 more)

We present the first Atacama Large Millimeter/submillimeter Array (ALMA) Band 3 (100 GHz) and Band 6 (243 GHz) continuum observations of the Arches cluster, one of the youngest and most massive stellar clusters in the Milky Way. We detect and characterise millimetre emission from 23 massive stars, including WN7-9h Wolf-Rayet stars, O-type supergiants and hypergiants. By combining our ALMA measurements with archival Very Large Array data spanning 5-22.5 GHz, we derive broadband radio-millimetre spectral indices and investigate the radial structure of stellar winds through frequency-dependent clumping diagnostics. The majority of Wolf-Rayet stars exhibit spectral indices clustered around $\alpha \approx 0.7-0.8$, consistent with predominantly thermal free-free emission from dense, partially optically thick winds. In contrast, several O-type stars show flat or negative broadband spectral indices, indicative of non-thermal synchrotron emission likely associated with colliding-wind binaries. Using millimetre flux densities, we derive clumping-scaled mass-loss rates spanning $\log(\dot{M}/\mathrm{M}_{\odot}\,\text{yr}^{-1})\approx-4.1$ to $-4.9$ for the WN stars and $-4.9$ to $-5.4$ for the O super-/hypergiants, consistent with expectations for luminous massive stars in the Galactic Centre environment. We find significant evidence of structured wind clumping at millimetre wavelengths that generally decreases with increasing radius, supporting structured wind models with strong inner-wind inhomogeneities. These results demonstrate the power of combined radio-millimetre observations for constraining mass-loss and wind structure in massive stars, and provide new insight into stellar feedback in extreme cluster environments.
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All authors James P. Perry, Raman K. Prinja, Danielle M. Fenech, Francisco Najarro

Mesoscale and Nanoscale Physics

Persistent currents, whirlpools, and local Chern markers in twisted TMD Chern insulators

Francesco Cioni, Lorenzo Cavicchi, Nazzareno Africani et al. (+4 more)

Recent materials advances have made it possible to fabricate twisted transition metal dichalcogenide homobilayers. These systems have been shown to host integer and fractional Chern insulating states. Because of spontaneous time reversal symmetry breaking, their ground state harbors intriguing spin-polarized currents with whirlpools on the moiré length scale that can be measured by scanning probe methods. We first provide a quantitative analysis of these persistent currents and then show that the maximum of the amplitude of the current density in the bulk of the sample is an accurate tracker of topological order. We conclude by calculating how the quantization of the Hall conductance is affected by finite-size effects.
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All authors Francesco Cioni, Lorenzo Cavicchi, Nazzareno Africani, Giacomo Mazza, Fabio Taddei, Amir Yacoby, Marco Polini

Cosmology and Nongalactic Astrophysics

Inflationary interpretation of the gravitational-wave signal in the European Pulsar Timing Array DR2 with constraints

Philippe Turgeon, Chiara Caprini, Anton Chudaykin et al. (+5 more)

The second data release of the European Pulsar Timing Array (EPTA) collaboration provides evidence for the presence of a gravitational-wave (GW) background. In this work, we explore a potential cosmological interpretation of this signal in terms of inflationary scenarios. We parametrize the tensor power spectrum in terms of the tensor-to-scalar ratio $r$, the tensor spectral index $n_t$, the reheating temperature $T_{\text{rh}}$, and the cut-off frequency $f_{\text{end}}$. We incorporate all relevant observational constraints, including those from the Cosmic Microwave Background, Big Bang Nucleosynthesis, and LIGO-Virgo-KAGRA observations. We demonstrate that imposing these constraints consistently reduces the region of parameter space that provides a viable interpretation of the EPTA signal, to $-11.66 \lesssim \log_{10}r \lesssim -1.45$, $1.32 \lesssim n_t \lesssim 2.47$, $1.78\text{ MeV} \lesssim T_{\text{rh}} \lesssim 28.2\text{ GeV}$, and $75.86\text{ nHz} \lesssim f_{\text{end}} \lesssim 14.45\text{ Hz}$ at the 95% confidence level. This favours the scenario in which the GW spectrum in the EPTA frequency band originates from tensor modes that re-entered the Hubble radius during the radiation-dominated era, allowing for a higher $r$ and a flatter spectrum. However, $T_{\text{rh}}$ must take very low values, which are challenging to explain theoretically.
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All authors Philippe Turgeon, Chiara Caprini, Anton Chudaykin, Martin Kunz, Delphine Perrodin, Ismael Cognard, Lucas Guillemot, Gilles Theureau