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Physics

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Friday 17 July

Materials Science

A Dynamical Phase-Field Model for the Optical Properties of Ferroelectrics

Aiden Ross, Anya Frazer, Venkatraman Gopalan et al. (+1 more)

Ferroelectric materials are promising platforms for controllable photonic devices because of the strong coupling between their spontaneous polarization and optical properties. Yet, these materials remain challenging to design because of the close connection between the ferroelectric domain structure and optical response, which no existing theoretical approach can capture. Here, we develop a dynamical phase-field model that directly couples the ferroelectric order to the local optical response by introducing an electronic polarization field. This approach enables the prediction of the spatially resolved temperature- and wavelength-dependent optical properties in complex ferroelectric microstructures. Applying this method to BaTiO3 thin films, we investigate the evolution of the local refractive index and electro-optic response under varying electric fields and temperatures. We show that the ferroelectric domain structure strongly modifies the local electro-optic response, exceeding 4000 pm/V near domain walls, several times larger than the bulk single crystal value (r_51=1300 pm/V). Our simulations quantitatively reproduce the electro-optic coefficient measured in BaTiO3 on silicon films and capture the temperature-dependent behavior across multiple ferroelectric phase transitions, revealing the role of phase competition and coexistence in determining the electro-optic response. More broadly, this work establishes a general approach for predicting light-matter interactions in complex ferroelectric microstructures, enabling the computational design of ferroelectric materials for photonics.
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All authors Aiden Ross, Anya Frazer, Venkatraman Gopalan, Long-Qing Chen

High Energy Physics (Theory)

Dressed States Call for Logarithmic Asymptotic Symmetries

Jorrit Bosma, Jeremy A. Mann, Charles Marteau et al. (+2 more)

Inspired by Wigner's classification of elementary particles as irreducible unitary representations of a spacetime symmetry group, we ask what group can give rise in this way to the quantum states of a particle dressed with clouds of infrared gauge bosons. We show that the answer is given by standard asymptotic symmetries (such as BMS in the gravitational case), supplemented by the logarithmic symmetries identified in arXiv:2305.05436. A corollary is the factorization of the Hilbert space of a dressed particle as a tensor product of the space of `naked' one-particle states with a Hilbert space of soft gauge bosons. The latter cannot be obtained without logarithmic transformations, which are ultimately responsible for the presence of a crucial Heisenberg central extension.
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All authors Jorrit Bosma, Jeremy A. Mann, Charles Marteau, Blagoje Oblak, Marios Petropoulos

Optics

Quantum scanning synthetic optical holography

Josué R. León-Torres, Byron Caiza, Nadia Baumann et al. (+7 more)

Synthetic optical holography (SOH) introduced holographic reconstruction into scanning optical microscopy, enabling quantitative phase imaging with sequential acquisition and point detection. Here, we extend this concept to the quantum regime by implementing SOH within quantum imaging with undetected light (QIUL). By integrating a controlled synthetic phase carrier into a scanning QIUL implementation, we retrieve amplitude and phase images of objects probed by mid-infrared (MIR) photons while detecting only their visible partners. We demonstrate the method on binary, transparent, and biological samples, showing complex-field reconstruction in a scanning quantum imaging system. This approach decouples spatial resolution from photon-pair spatial correlations and establishes a route toward diffraction-limited, label-free MIR phase imaging with visible-wavelength detection.
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All authors Josué R. León-Torres, Byron Caiza, Nadia Baumann, Sebastian Töpfer, Anna Mühlig, Orlando Guntinas-Lichius, Karin Burger, Frank Setzpfandt, Markus Gräfe, Valerio Flavio Gili

Nuclear Experiment

Rapid structural evolution of neutron-rich silicon isotopes toward N = 28

G. L. Zimba, H. Iwasaki, B. A. Brown et al. (+27 more)

Neutron-rich Si isotopes represent a unique case of shell evolution, exhibiting a robust shell closure at $N=20$ and pronounced quadrupole collectivity at $N = 28$. We report lifetime measurements of excited states in $^{40}$Si and the first simultaneous lifetime and heavy-ion inelastic-scattering measurements in $^{41}$Si. In $^{40}$Si, the extracted lifetimes for the $2_1^+$ and $(2_2^+)$ states indicate moderate quadrupole collectivity at $N=26$, together with signatures of triaxiality. In $^{41}$Si, two near-degenerate states at 570 and 658~keV exhibit comparable $B(E2)$ strengths as extracted from inelastic scattering, while the measured lifetimes indicate dominant $M1$ decays. The combined lifetime and inelastic-scattering results suggest an evolution toward oblate shape, consistent with large-scale shell-model predictions.
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All authors G. L. Zimba, H. Iwasaki, B. A. Brown, Y. Utsuno, N. Shimizu, N. Aoi, M. Basson, T. Beck, J. Chen, J. Chung-Jung, A. Douglas, A. Ertoprak, P. Farris, C. Fransen, A. Gade, S. A. Gillespie, A. Hill, K. Kolos, D. Lempke, I. Lihtar, T. Mijatović, S. Neupane, S. Noji, T. Parry, A. Revel, R. Salinas, A. Sanchez, E. Schieb, D. Weisshaar, Y. Yamamoto

Astrophysics of Galaxies

Morphologies of SAGAbg low-mass galaxies in Legacy Survey multi-band imaging: dependence on stellar masses, star-formation rates and low-redshift evolution

Joy Bhattacharyya, Guinevere Herron, Yasmeen Asali et al. (+4 more)

The optical morphologies of low-mass galaxies can be used to directly trace their assembly and constrain models of galaxy evolution. We select a sample of 6211 low-mass ($7\lesssim {\rm log}(M_{\ast}/M_{\odot})\lesssim 10$) star-forming galaxies from the SAGAbg catalog that has high-completeness at low-redshifts ($z<0.1$). We obtain their galaxy maps in the $griz$ - bands of the Legacy Surveys and apply STATMORPH to calculate non-parametric morphological measures including the Gini index, $M_{20}$ measure, and CAS parameters. We study how resolution and signal-to-noise affect the morphology measures and find that the bulge strength measurements are the most reliable. The sequence in Gini$-M_{20}$ space is directly linked to the star-forming sequence of galaxies and is dominated by Sb/Sc/Ir morphologies. The $g$-band light distributions are the least concentrated among all the bands. The systematic trends of $M_{20}$ with respect to stellar mass and GALEX NUV-derived specific star formation rate (sSFR) strongly indicate that the galaxies with flatter light profiles are less massive with higher sSFR and vice-versa. We statistically infer that star-forming low-mass galaxies predominantly have disk morphologies with bulges becoming more prominent in quenched systems at higher masses (${\rm log}(M_{\ast}/M_{\odot})\gtrsim 9$).
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All authors Joy Bhattacharyya, Guinevere Herron, Yasmeen Asali, Abby Mintz, Mithi A. C. de los Reyes, Yao-Yuan Mao, Annika H.G. Peter

Materials Science

Atomistic mechanism of corrosion-induced grain boundary migration in NiCr alloys in molten FLiNaK

Sadia Khan, Hamdy Arkoub and Miaomiao Jin

Corrosion of Ni-Cr structural alloys in molten fluoride salts is a persistent material degradation problem, yet the atomistic role of grain boundaries in this process remains poorly understood. Here we use reactive molecular dynamics to investigate corrosion of NiCr alloys in molten FLiNaK across four representative grain boundaries ($\Sigma3(111)$, $\Sigma11(113)$, $\Sigma5(012)$, and $\Sigma5(013)$) and corresponding bulk surfaces. Surface crystallography controls the initial dissolution stage, while grain boundary character governs the spatial localization and longer-time evolution of corrosion. We further identify a corrosion-driven grain boundary migration mechanism in which fluorine localization, preferential chromium dissolution, and vacancy-mediated mobility together drive interfacial motion away from the dealloyed region. The coherent $\Sigma3(111)$ boundary suppresses these processes, indicating low-energy special boundaries as targets for grain boundary engineering of corrosion-resistant Ni-Cr alloys.
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Quantum Physics

Fast logical operations in quantum LDPC codes using simple resource states

Mark Webster and Nicolas Delfosse

Quantum LPDC codes provide a substantial reduction in qubit overhead required for fault-tolerant quantum computation compared to surface code, thanks to their high encoding rate. However, operating simultaneously on multiple logical qubits encoded in the same block is more challenging and may slow down logical operations. Prior work addresses this problem by designing complex resource states to perform logical measurements in LDPC codes. Here, we propose an approach that only consumes cat states. Whereas previous work on cat-based measurements focuses on a single logical measurement, we design a protocol for the joint measurement of $\ell$ commuting logical operators. The key ingredient is the design of a scheduler code determining the measurement sequence and allowing for the decoding of all logical measurement outcomes. Numerical simulations with the LDPC codes Q70 and Q102 of the walking cat architecture show a speed-up of nearly $3\times$ over Viterbi measurements for the measurement of $\ell=20$ commuting logical operators. Combining our fast logical measurements with a new variant of the CliNR partial error correction scheme, we achieve a speed-up of up to $74\times$ for random Clifford circuits. Our approach also applies to non-Clifford gates, producing a speed-up of up to $5\times$ for Toffoli gates.
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Astrophysics of Galaxies

Euclid: Calibrating distances from surface brightness fluctuations with Early Release Observations of the Fornax cluster

R. Habas, M. Cantiello, G. Riccio et al. (+170 more)

Surface brightness fluctuations (SBF), the pixel-to-pixel variations in flux that arise from the statistical distribution of stars in galaxy images, provide a powerful tool to measure redshift-independent distances from photometric data alone. This method is particularly important in the era of large imaging surveys, such as those carried out during the Euclid mission. Here we present the first application of SBF to Euclid data, using the FAST-SBF code to measure stellar fluctuation amplitudes in the $I_\mathrm{E}$ band for a sample of galaxies in the Early Release Observations (ERO) of the Fornax galaxy cluster. Although the Euclid data reduction pipeline is not optimized for SBF measurements, extensive testing suggests that we are able to extract robust results. We calibrate the absolute fluctuation magnitude $\overline{M}_\mathrm{IE}$ as a function of the $(I_\mathrm{E}{-}H_\mathrm{E})$ colour for 15 galaxies in Fornax, then test this relation on galaxies in two other ERO fields: the Perseus cluster and dwarf satellite candidates around NGC 6744. Overall, we find reasonable agreement with distances in the literature and good agreement in cases where FAST-SBF indicates the measurements are robust. Finally, we compare our results against Stellar Population Tools (SPoT) simple stellar population models, and discuss the possibility of using SBF with Euclid to probe the underlying stellar populations of the galaxies.
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All authors R. Habas, M. Cantiello, G. Riccio, G. Raimondo, N. Hazra, S. Mei, A. Lançon, G. D'Ago, R. Scaramella, L. K. Hunt, J.-C. Cuillandre, J. P. Blakeslee, J. B. Jensen, E. Brocato, D. Carollo, P.-A. Duc, M. Kluge, R. Laureijs, O. Marchal, F. R. Marleau, M. Mirabile, R. F. Peletier, M. Poulain, R. Sánchez-Janssen, T. Saifollahi, M. Schirmer, E. Sola, M. Urbano, K. Voggel, B. Altieri, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, R. Bender, A. Biviano, E. Branchini, M. Brescia, S. Camera, V. Capobianco, C. Carbone, V. F. Cardone, J. Carretero, S. Casas, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, H. Degaudenzi, G. De Lucia, H. Dole, F. Dubath, X. Dupac, S. Escoffier, M. Fabricius, M. Farina, R. Farinelli, S. Ferriol, S. Fotopoulou, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, B. Gillis, C. Giocoli, P. Gómez-Alvarez, J. Gracia-Carpio, A. Grazian, F. Grupp, S. V. H. Haugan, H. Hoekstra, W. Holmes, I. M. Hook, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, B. Joachimi, S. Kermiche, A. Kiessling, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, A. M. C. Le Brun, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, O. Mansutti, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, E. Medinaceli, M. Melchior, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, R. Nakajima, C. Neissner, R. C. Nichol, S.-M. Niemi, J. W. Nightingale, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, A. Pezzotta, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, B. Rusholme, R. Saglia, Z. Sakr, D. Sapone, B. Sartoris, P. Schneider, M. Scodeggio, A. Secroun, E. Sihvola, P. Simon, C. Sirignano, G. Sirri, L. Stanco, P. Tallada-Crespí, A. N. Taylor, H. I. Teplitz, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, F. M. Zerbi, I. A. Zinchenko, E. Zucca, M. Sereno

Cosmology and Nongalactic Astrophysics

Constraining primordial non-Gaussianity and parity-violation through Scalar-Induced Gravitational Waves with next-generation ground-based interferometers

Ilaria Caporali, H. V. Ragavendra, Angelo Ricciardone et al. (+1 more)

In this work, we investigate the prospects for probing primordial non-Gaussianity and associated symmetry of parity through scalar-induced gravitational waves (SIGWs), with third-generation gravitational-wave detectors. We develop a framework that accounts for contributions to the energy density spectrum of GWs arising from the scalar non-Gaussianity quantified by bispectrum and trispectrum, and perform parameter inference using simulated data from Einstein Telescope and Cosmic Explorer. The parity-odd component of the scalar trispectrum induces circular polarization in the stochastic gravitational-wave background (SGWB), providing a direct probe of parity-violation in the primordial Universe. We show that future interferometers can place competitive constraints on the parity-odd scalar trispectrum, along with the bispectrum and parity-even trispectrum. Moreover, we include the astrophysical contribution, which could act as a foreground for the SIGWs. We show that, despite the addition of such a foreground, we are still able to effectively constrain the cosmological parameters related to SIGWs and the astrophysical parameters as well.
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All authors Ilaria Caporali, H. V. Ragavendra, Angelo Ricciardone, Nicola Bartolo

Solar and Stellar Astrophysics

A multi-source dataset for solar energetic particle forecasting

Yian Yu, Yang Chen, Lulu Zhao et al. (+3 more)

Solar energetic particle (SEP) event forecasting often involves integrating heterogeneous observations that differ in cadence, temporal coverage, format, and historical availability, posing challenges for reproducible analysis of data-driven approaches. This paper presents SEP-PRISM Data, a curated multi-source dataset designed for 24-hour-ahead forecasting of operational SEP events, defined as proton flux exceeding 10 pfu in the GOES > 10 MeV channel. SEP-PRISM Data integrates flare records, active-region magnetic field parameters, coronal mass ejection (CME) catalog data, GOES soft X-ray flux, and historical proton flux into a common window-based representation spanning 3 February 1986 to 10 September 2025. To improve temporal coverage and cross-source consistency, SHARP and SMARP magnetic products were aligned into a unified SMHARP archive, and CME records from DONKI and CDAW were aligned into a unified CDAWDONKI event set. Predictor variables were summarized over fixed non-overlapping 24-hour historical windows using minimum, mean, and maximum statistics and paired with targets defined over the subsequent 24-hour window, forming a supervised learning dataset. The resulting SEP-PRISM Data contains 14,464 labeled samples, including 650 positive operational SEP cases, and is intended to support reproducible benchmarking, model development, feature analysis, and future studies of space weather forecasting.
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All authors Yian Yu, Yang Chen, Lulu Zhao, Kathryn Whitman, Ward Manchester, Tamas Gombosi

General Relativity and Quantum Cosmology

Comparison of $f(R,T)$ Gravity with Multiple Datasets

Vincent R. Siggia and Eric D. Carlson

We examine $f(R,T)=R+\lambda T^\epsilon$ gravity models by finding the best fit parameters for various values of $\epsilon$. This is accomplished by analyzing data from the cosmic microwave background, baryon acoustic oscillation observations, cosmic chronometer, and Type Ia supernovae introducing correlations and radiation effects to our previous work. We find the probability distribution for the best fit model around the value of $\epsilon=0.010^{+0.013}_{-0.021}$, consistent with the standard cosmological model value of $\epsilon = 0$.
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Geophysics

Broadband Multi-Aperture Passive Scholte-Wave Imaging Using Seabed Distributed Acoustic Sensing

Anna Titova and Andrey Bakulin

Shallow-water ocean forcing provides strong broadband passive Scholte-wave illumination along a seabed distributed acoustic sensing cable on the Texas Gulf Coast. We exploit this illumination through direct processing of the uncorrelated wavefield, long-duration frequency-wavenumber stacking, and a multi-aperture strategy that preserves high-frequency spatial localization while resolving low-frequency modes. Constant-wavenumber slices enable spatially consistent multimode tracking across successive array centers. The resulting dispersion spans approximately 0.3-4.5 Hz and supports 400 one-dimensional inversions along a 51-km cable segment. These profiles form a pseudo-2D shear-wave velocity model extending from the near seafloor to approximately 2 km depth. Broad shallow low-velocity intervals are consistent with softer incised-valley fill within stiffer Pleistocene deposits. The results demonstrate that existing seabed fiber infrastructure, when coupled with strong shallow-water passive illumination, can deliver broadband regional shear-wave imaging, while higher-frequency active sources remain necessary to resolve the uppermost several meters.
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High Energy Physics (Theory)

Elastic stiffness of three-dimensional black holes and wormholes from Liouville line defects

Jeevan Chandra and Boris Post

We study elastic deformations of thin-shell black holes and wormholes in AdS$_3$ gravity. These geometries are sourced by line defects in the dual conformal field theory, and their shape and mass distribution define elastic moduli of the gravitational saddle. We compute the quadratic response of the partition function to these deformations, defining stiffness kernels for both transverse shape fluctuations and inhomogeneous mass-density fluctuations. The computation of the stiffness kernels can be realized as a hyperbolic response to a conformal welding problem which reduces to the universal Schwarzian response in the heavy-shell limit. The stiffness kernels are two-point functions of defect-local operators in CFT: the displacement operator, which measures the response to shape deformations, and a mass-density operator, which measures the response to local changes in the shell density. We compute the spectrum of these operators in the semiclassical limit, in various black hole and wormhole backgrounds. The spectrum can be discrete or continuous depending on the existence of a non-compact direction transverse to the shell in the geometry. We also provide a Lorentzian interpretation for the stiffness kernels using linear response theory and compute the relaxation time scales towards the corresponding transient deformations in the dual holographic CFT. Lastly, we compute the effect of these elastic deformations on black hole microstate statistics and black hole entropy.
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Cosmology and Nongalactic Astrophysics

Large deviations for halos and voids: beyond perturbative non-gaussianities

Martin Teuscher, Ruth Durrer, Julien Grain et al. (+2 more)

The excursion-set formalism provides a key connection between primordial density fluctuations and the abundance of cosmic structures such as dark matter halos and voids, traditionally assuming Gaussian random walks. In this work, we extend this framework to fluctuations whose distribution presents strongly non-Gaussian tails. Such tails are beyond the reach of perturbative approaches to primordial non-Gaussianity based on moment expansion. We address the problem with rigorous, analytical derivations relying on the large deviation principle, suited for the study of rare fluctuations. We derive new first-passage time distributions for random walks with non-Gaussian statistics and obtain updated predictions for the halo mass function. We also study the two-barrier problem relevant to cosmic void formation, leading to a new analytical prediction for the void size function, with improved accuracy on large scales. Our results demonstrate the potential of large deviation techniques as a bridge between inflationary scenarios, often leading to strongly non-Gaussian tails, and late-Universe observables.
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All authors Martin Teuscher, Ruth Durrer, Julien Grain, Killian Martineau, Aurélien Barrau

Instrumentation and Detectors

Radiopurity material assays and radiation exposure projections for superconducting qubit measurements at SNOLAB

Y. Ahmed, B. Binoy, R. Bunker et al. (+21 more)

Interactions of cosmic rays and other forms of ionizing radiation pose a significant challenge to the reliable operation of state-of-the-art quantum devices and error correction in quantum computing based on superconducting circuits which are typically fabricated on semiconductor substrates. Shielded by 2 km of rock overburden, the Cryogenic Underground TEst facility (CUTE) at SNOLAB provides a unique ultra-low radiation environment to probe the performance of quantum technologies with a particular interest in quantum coherence studies. In this article, we present the findings of an extensive material assaying program in preparation for the first underground operation of superconducting qubits at SNOLAB. The radioactivity levels identified by the material assays enter a thorough Monte Carlo study based on the Geant4 particle physics tracking code. From these simulations, we estimate the rates of energy deposits from radiogenic sources expected for a quantum-device assembly operated in the CUTE facility. We further characterize the spectral components of the projected background and identify the dominant particle interaction types. Finally, we outline how crystal dynamics simulations using the G4CMP solid-state physics extension for Geant4 can inform the community-wide efforts to identify effective strategies to mitigate the effects of high-energy particle impacts.
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All authors Y. Ahmed, B. Binoy, R. Bunker, D. Chauhan, P. Delsing, R. Germond, J. Hall, Z. Hong, A. Iqbal, V. Iyer, A. Klepikova, A. Kubik, S. P. Mantry, A. C. Masuskapoe, C. C. Monk, G. Peng, P. Qin, W. Rau, T. Reynolds, M. Stukel, C. M. Wilson, B. Zatschler, S. Zatschler, A. Zuniga

Strongly Correlated Electrons

Quantum Fisher information of magnetic quantum phase transition on Kondo lattice

Yuan Fang, Lei Chen, Mounica Mahankali et al. (+4 more)

Strange metals exemplify highly collective quantum many-body systems that call for new means of characterization, and there is considerable potential for quantum information approaches contributing to the cause. We investigate multipartite entanglement across the quantum phase transition of a Kondo lattice model using the quantum Fisher information (QFI). We show that the QFI associated with the spin components transverse to the order parameter characterizes the destruction of heavy quasiparticles in the Kondo-destroyed magnetic-ordered phase. The physical origin of this observation is elucidated through an analysis of the antiferromagnetic Heisenberg model. We propose to test the results in terms of both unpolarized and polarized inelastic neutron scattering measurements in the ordered part of the heavy fermion phase diagram. Our findings illustrate how different operators of a many-body system can be employed to not only witness multipartite entanglement in different sectors and but also elucidate the overall physics across different parts of the phase diagram.
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All authors Yuan Fang, Lei Chen, Mounica Mahankali, Fang Xie, Yiming Wang, Shouvik Sur, Qimiao Si

Fluid Dynamics

Data-driven identification of multiscale self-similarity and asymptotic matching

Kaixin Zhu, Nikos Bempedelis and Konstantinos Steiros

A central problem in fluid mechanics is the identification of self-similarity, which reveals the underlying scaling behaviour of a flow. Recently, a data-driven framework proposed by Bempedelis et al. (2025 J. Fluid Mech., vol. 1020, A11) has enabled the extraction of single-scale self-similarity from data, without prior knowledge of the governing equations. However, many physical systems are inherently multiscale and therefore require more general approaches. Building on this foundation, we develop an algorithm for the systematic identification of multiscale self-similarity. The algorithm is first applied to two canonical fluid-mechanical problems: turbulent channel flow and late-stage homogeneous decaying turbulence characterised by classical dissipation laws. In both cases, the algorithm successfully identifies inner and outer self-similarity from numerical data and recovers the corresponding similarity expressions. In the intermediate region of both problems, the algorithm identifies similarity expressions that are independent of both the inner and outer scales, providing a novel data-driven route to recovering the corresponding scaling laws: the logarithmic law in turbulent channel flow and the -5/3 law in late-stage homogeneous decaying turbulence. Moreover, the algorithm uncovers corrections to both laws: one linked to the power-law scaling proposed by Barenblatt (1993 J. Fluid Mech., vol. 248, 513–520), and the other yielding an improved approximation of the energy spectrum. The algorithm is then applied to early-stage homogeneous decaying turbulence, characterised by the nonclassical dissipation law. It identifies the same inner similarity as in the late stage, but different outer similarity expressions.
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High Energy Physics (Phenomenology)

Order-reversed Kubo formulas in relativistic kinetic theory

Sangyong Jeon, Juhee Hong and Alina Czajka

Using the stress-energy tensor response functions obtained in the Anderson-Witting model of kinetic theory with non-zero mass, we verify that these response functions satisfy the required analytic conditions and are fully consistent with the recently derived Kubo formulas in Ref.[1].
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High Energy Physics (Phenomenology)

Learning Standard Model structure from LHC data with Riemannian flow matching

Midori Kato, Kevin A. Urquía-Calderón, Inar Timiryasov et al. (+1 more)

In this work we demonstrate that a single transformer-based generative model can capture Standard Model structure spanning five decades of invariant mass, from the sub-GeV regime to the TeV continuum, a range that no single Monte Carlo sample covers. To achieve this we design ShellFlow, a Riemannian conditional flow matching model that, given the recorded event composition, generates each particle on its on-shell manifold. Its only physics priors are the on-shell condition and the invariant-mass formula. The model is trained on $\sim 10^{9}$ real $pp$ collision events from the ATLAS Open Data 13~TeV release and told nothing else. From a single training run, the model learns to reproduce all of the following: intra-particle kinematics, the dilepton resonances ($J/\psi$, $\Upsilon$, $Z$) at their PDG positions, the leptonic Weinberg angle, the $W$ and top-quark masses, and inter-particle correlations that enter no training objective. A substantial fraction of the Standard Model is thus learnable directly from recorded collision data.
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All authors Midori Kato, Kevin A. Urquía-Calderón, Inar Timiryasov, Oleg Ruchayskiy

Mesoscale and Nanoscale Physics

Excitonic structure in CsPbBr$_3$ nanocubes, nanorods and nanoplatelets: the effect of dimensionality

Jose L. Movilla, Josep Planelles and Juan I. Climente

We present a theoretical study comparing the excitonic ground state properties of CsPbBr$_3$ nanocrystals with different dimensionality: nanorods (quasi-1D), nanoplatelets (quasi-2D) and nanocubes (quasi-3D). All three systems are described on equal footing, by means of a general variational effective mass model, which captures the influence of quantum confinement, dielectric confinement, electron-hole correlations and polaronic effects (within a Haken model). The strongly confined directions squeeze the exciton (X) wavefunction and enhance Coulomb attractions along the weakly confined directions. This stimulates superradiance, thus making radiative recombination rates speed up from cubes to platelets and to rods, in line with recent experiments. The anisotropic local field factor is a secondary, yet non-negligible, mechanism further enhancing radiative rates. X binding energies are also determined primarily by the directions of strong confinenement, which is also consistent with experiments. Weakly confined directions become however influential for small aspect ratios. Dielectric confinement plays a major role in determining the binding energies, and less so in the interparticle-distances. For all dimensionalities, the biexciton (XX) geometry is that of a distorted tetrahedron, rather than squared or linear distributions that would result in Coulomb-governed 2D and 1D structures.
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High Energy Astrophysical Phenomena

X-ray polarization of Z-type neutron star low-mass X-ray binaries – II. Spectropolarimetric analysis

Andrea Gnarini, Francesco Ursini, Giorgio Matt et al. (+8 more)

IXPE has provided for the first time detailed energy- and time-resolved X-ray polarimetry of Z-type neutron star low-mass X-ray binaries (NS-LMXBs) as they move along their color-color diagrams (CCDs). These sources can reach the highest polarization observed for NS-LXMBs in the 2-8 keV range when they move along the horizontal branch. In a previous paper, we characterized the spectral state of a sample of Z-sources using the CCD and estimated the polarization with model-independent analysis. Here, we present detailed spectropolarimetric analysis for each source on each branch using data from IXPE, NICER, and NuSTAR. The continuum X-ray emission of all the sources is well described with a combination of thermal accretion disk emission plus a harder Comptonized component. In addition, reflection features, in particular the relativistically broadened Fe line, are observed for our sources, except GX 5-1. For most of the sources and branches, the main contribution to the X-ray emission and polarization is due to Comptonization: moving from the horizontal branch (HB) to the normal branch (NB), the polarization degree (PD) in the 2-8 keV band varies from about 6% to 3-4%, while the PD is loosely constrained in the flaring branch (FB), due to the shorter exposures. These PD values are significantly higher than theoretical expectations for typical spreading or boundary layer configurations. The polarization of the disk is generally lower (below 3%) but still higher than predictions for an electron scattering-dominated, plane-parallel atmosphere above the disk observed at the corresponding inclination. Moreover, the polarization angle (PA) of the disk seems to be significantly misaligned and not perpendicular to that of Comptonization. We find no correlation between the polarization signal and the inclination, nor with the contribution of reflected photons throughout the Z-track.
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All authors Andrea Gnarini, Francesco Ursini, Giorgio Matt, Stefano Bianchi, Fiamma Capitanio, Massimo Cocchi, Sergio Fabiani, Ruben Farinelli, Philip Kaaret, Lorenzo Marra, Antonella Tarana

High Energy Astrophysical Phenomena

Eccentricity as a Magnifying Glass: Precision Population Inference Enabled by Eccentric Neutron Star-Black Hole Mergers

Alberto Salvarese, Hsin-Yu Chen, Aaron Zimmerman et al. (+1 more)

The formation history of compact binary systems remains one of the key open questions in astrophysics. Theoretical studies generally favor isolated binary evolution for neutron star-black hole (NSBH) systems, which tends to produce nearly circular orbits. However, recent analyses of the gravitational-wave event GW200105 indicate that its source has measurable eccentricity, suggesting that alternative formation channels may also contribute. It has been shown that the intrinsic parameters of eccentric NSBH mergers, such as the component masses and spins, are much better measured than circular mergers with LIGO-Virgo-KAGRA (LVK) observatories. We explore how such eccentricity-enhanced parameter measurements can affect the inference of NSBH formation channels. We find that sharper measurements of the effective spin parameter $\chi_{\rm eff}$ increase the fraction of systems for which negative values can be confidently identified, allowing for the clear measurement of a spin-orbit misaligned event every $\sim 2.5$ eccentric NSBH detections for an isotropically distributed population in the fifth LVK observing run (O5). Improved neutron star (NS) mass measurements provide better constraining power for NS mass distributions, potentially revealing structure and tightening the bounds that can be drawn on their upper and lower masses. Similarly, the recovery of a metallicity-dependent BH mass distribution is improved by eccentricity-enhanced measurements. Finally, we show that the proposed population-level eccentricity distribution for dynamical-formation channels can be tested by the end of O5.
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All authors Alberto Salvarese, Hsin-Yu Chen, Aaron Zimmerman, Snehal Tibrewal

High Energy Astrophysical Phenomena

Impact of eccentricity and higher-modes on neutron star-black hole parameter estimation

Snehal Tibrewal, Aasim Jan, Aaron Zimmerman et al. (+1 more)

Detections of gravitational waves from neutron star-black hole systems provide avenues for studying extreme matter, constraining binary formation channels, and testing the nature of compact objects in strong gravity. Eccentric signatures in the signal further enhance this potential by improving parameter estimation and offering clues about binary formation. Because eccentricity is primarily imprinted during the inspiral phase, it is often weakly constrained or missed entirely in binary black hole observations; in contrast, neutron star-black hole systems produce longer in-band signals, enabling more precise measurements of eccentricity and leaving a distinct imprint on parameter inference. In this work, we present a systematic parameter-estimation study exploring the impact of eccentricity on inference using injections simulated with the state-of-the-art eccentric waveform model SEOBNRv5EHM. We find that for systems like GW200105_162426, the measurement precision of eccentricity and correlated parameters improves as eccentricity increases, yielding tighter constraints at larger eccentricities. For the highest eccentricity considered in this study, $e=0.25$, we recover eccentricity with $1\sigma$ uncertainty as low as $4\times10^{-4}$. In addition, the constraints on effective spin $\chi_\mathrm{eff}$ and mass ratio $q$ improve relative to the quasi-circular case by factors of $\sim13$ and $\sim20$, respectively. On the other hand, we find no significant improvement in extrinsic parameters such as luminosity distance and sky localization, suggesting that for systems like GW200105_162426, the additional information provided by eccentricity in this sector is either negligible or degenerate with the information provided by higher-order modes.
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All authors Snehal Tibrewal, Aasim Jan, Aaron Zimmerman, Hsin-Yu Chen

High Energy Physics (Theory)

Gravitational index of the D1-D5-P black string

Silvia Georgescu, Sameer Murthy and Andrew Svesko

We present saddle-points of the Euclidean Gravitational Path Integral (GPI) corresponding to the supersymmetric index of the D1-D5-P black string. These saddles are complex, supersymmetric, non-extremal solutions of 10-dimensional IIB supergravity theory with arbitrary inverse temperature $\beta$. The solutions carry fixed monopole charges $Q_1$, $Q_5$, $Q_n$, and angular momentum $J_L$ equal to the extremal supersymmetric black string. Crucially, the solutions have fixed angular velocity $\Omega_{R} = - 2 \pi i /\beta$, which is the chemical potential dual to $J_R$. This implements the insertion of $(-1)^{F}$ in the GPI. The Gibbons-Hawking on-shell action is temperature-independent and agrees with the supersymmetric index of the extremal black string carrying the same monopole charges. Upon taking a finite-temperature near-horizon decoupling limit, we obtain solutions of the form $S^3$ fibered over BTZ. Although these near-horizon solutions have finite holomorphic and anti-holomorphic modular parameters, their on-shell action reproduces the Cardy formula of the holomorphic elliptic genus of the dual D1-D5 SCFT$_2$.
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Chemical Physics

Nonadiabatic excited-state dynamics with quantum Monte Carlo-trained machine learning: azomethane as a stringent test

Alfonso Annarelli, Emiel Slootman and Claudia Filippi

We introduce quantum Monte Carlo (QMC)-trained multi-state machine-learned (ML) force fields for nonadiabatic excited-state dynamics, targeting photochemical processes in which the electronic character changes along the reaction path and a consistent correlated description is required. In this framework, variational Monte Carlo wave functions combine compact selected configuration-interaction expansions with a Jastrow factor that explicitly accounts for dynamical correlation, while neural networks convert the stochastic QMC data into smooth potential energy surfaces for large surface-hopping ensembles. We apply this approach to azomethane, a demanding test case involving torsional relaxation through conical-intersection regions and C–N bond dissociation on the hot ground state. Benchmark calculations support the accuracy of the QMC reference data and show robust force convergence across isomerization and dissociation geometries. The QMC-trained dynamics preserves the expected photoisomerization mechanism, strongly reduces the excessive C–N breaking obtained with complete active space self-consistent field, and predicts a small but non-negligible prompt dissociation component after internal conversion, with a timescale consistent with femtosecond-resolved mass-spectrometry experiments. These results establish QMC-ML as a practical route to nonadiabatic photochemical dynamics with accurate wave-function reference data.
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Computational Physics

CADAQUES: A Cost-Aware Dual Architecture for Query-Efficient Autonomous Discovery

Jorge Bravo-Abad

Autonomous discovery systems couple a resource that answers queries (a simulator, instrument, or analytic model) to an algorithm that selects what to query next. Most software frameworks for this loop inherit the control structure of numerical optimization: campaigns run for a fixed number of iterations, query costs are absent from the programming interface, and decision-making is treated as free. In practice, queries may differ in cost by orders of magnitude, and planners built on large language models or expensive surrogates consume resources of their own. Here we present CADAQUES, an open-source Python framework built on one architectural principle: cost is a first-class primitive of the discovery loop. CADAQUES separates the loop into two structural protocols, an Oracle that answers queries and a Driver that proposes them, and charges both evaluations and decisions against a common vector-valued budget spanning wall time, CPU hours, monetary cost, and language model tokens. An append-only ledger records, for each transaction, the cost declared before execution and the cost settled afterwards, making their discrepancy an observable property of the campaign. We evaluate the architecture by locating the critical temperature of the two-dimensional Ising model from noisy finite-size estimates against the exact thermodynamic-limit reference. In this noisy setting, strategies that concentrate around the best observed result can be misled by noise-induced peaks, whereas a schedule that explores with cheap low-fidelity queries and refines with higher-fidelity ones yields lower and less variable errors than high fidelity throughout, at the studied budget scale. Metering adds tens of microseconds per iteration, three orders of magnitude below the cheapest oracle query. The framework is MIT-licensed and archived at Zenodo (doi:10.5281/zenodo.21293589).
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Atmospheric and Oceanic Physics

Global kilometer-scale climate simulations: new opportunities for climate services

David Saint-Martin, Olivier Geoffroy and Gildas Dayon

Climate services are essential for risk management and economic planning. This paper presents a century-long simulation performed with the ARP-GEM global atmosphere model at 2.6 km horizontal resolution. This simulation was specifically designed to complement and extend the set of simulations used in the latest version of the French climate services. A key feature is its global coverage at kilometer-scale resolution, enabling the representation of phenomena that depend on such fine scales. This is especially relevant for French climate services, as many processes - particularly over islands and resolution-sensitive regions - are currently overlooked in global simulations. Additionally, France's overseas territories are globally dispersed, and this approach allows their representation within a single framework. A limitation of this simulation is the use of prescribed sea surface temperatures due to the lack of ocean coupling; this will be addressed in future work. The present study demonstrates the feasibility of this approach and highlights the benefits of this new generation of climate modeling for climate services.
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Quantum Physics

Reverse engineering of single-qubit quantum gates

Gustavo Fernandes da Costa, Leonardo K. Castelano and Emanuel Fernandes de Lima

In this work, we address the problem of designing single-qubit quantum gates by means of a linearly-polarized field. We show that any desired one-qubit gate corresponding to a special unitary matrix can be generated by a modulated sinusoidal field. The only approximation involved is the rotating-wave-approximation. The formula for the control field is obtained by inverting the equation of motion for the evolution operator and imposing the conditions for the desired gate. We give a simple procedure to obtain closed analytical formulas for the fields in terms of a priori chosen dynamical functions. Additionally, these dynamical functions can depend on tunable free parameters intentionally introduced to meet a desired performance criteria.
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High Energy Physics (Theory)

Localized Vector Modes on Local Cosmic Strings

Sergio Alameda-Calvo, Jose J. Blanco-Pillado and Jose Queiruga

We investigate the dynamics of vector excitations localized on cosmic strings in the Abelian-Higgs model. These confined gauge field fluctuations behave as massive vector degrees of freedom propagating along the string. We show that they remain bounded for all values of the scalar self coupling $\lambda$, including parameter regimes in which the previously studied conventional shape mode is no longer present. After determining their spectra and spatial profiles, we analyze their decay through nonlinear coupling to bulk radiation. Their amplitudes exhibit the characteristic power law relaxation associated with non-linear radiation. For sufficiently large $\lambda$ the scalar radiation channel becomes kinematically inaccessible and the decay is instead mediated by quasinormal modes which can be interpreted as Feshbach resonances of the string. We then study the full $3+1$ dimensional dynamics of the vector-excited string. Field theory simulations reveal a parametric instability between the vector mode and the Goldstone sector. In contrast to the shape mode, the vector mode resonantly excites both transverse directions simultaneously. In addition, we build an effective model that captures the instability and identifies the nonlinear couplings responsible for it. Our results show that vector excitations constitute a long-lived massive degree of freedom with a non-trivial role in the dynamics of local strings.
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High Energy Astrophysical Phenomena

Discovery of $\gamma$-Ray Pulsations from the Extreme-Spin-Down Millisecond Pulsar PSR J0435+3233

Mengqing Zhang, Shengbin Pei and Pengfei Zhang

Motivated by the recent discovery of PSR~J0435+3233, a millisecond pulsar with an exceptionally large period derivative of $\dot{P}=4.9\times10^{-17}\ {\rm s\,s^{-1}}$ and a high spin-down luminosity of $\dot{E}=5.89\times10^{37}\ {\rm erg\,s^{-1}}$, we analyze $\sim$17~yr of observations obtained with the Fermi Large Area Telescope for the pulsar. We identify the cataloged source 4FGL~J0435.5+3232, located only $0.01^{\circ}$ from the radio timing position, as the $\gamma$-ray counterpart of PSR~J0435+3233. Using $\gamma$-ray events collected within the validity interval of the radio timing ephemeris, we detect its $\gamma$-ray pulsations at a $\sim6.8\sigma$ confidence level. In this interval, the phase-resolved analysis shows that the pulsed emission is concentrated predominantly within the rotational-phase of $\phi\sim0.44$–$0.69$. We also derive its $\gamma$-ray luminosity of $L_{\gamma}=6.26\times10^{32}\ {\rm erg\,s^{-1}}$, assuming a distance of 1.2~kpc and isotropic emission. This luminosity corresponds to an apparent $\gamma$-ray efficiency of $\eta_{\gamma}\sim1.1\times10^{-5}$, revealing an exceptionally low $\gamma$-ray output despite the pulsar's young-pulsar-like rotational-energy budget. Our detection establishes PSR~J0435+3233 as a $\gamma$-ray MSP, and the striking combination of its high spin-down power and low apparent $\gamma$-ray efficiency provides a new probe of particle acceleration, radiation beaming, and viewing geometry in the magnetospheres of millisecond pulsars with extreme rotational properties.
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