Solar and Stellar Astrophysics
Stellar masses and ages in Gaia Data Release 4 from the Final Luminosity Age Mass Estimator algorithm
Orlagh L. Creevey, Laia Casamiquela, Yveline Lebreton et al. (+23 more)
The masses and ages of
stars are key quantities for understanding exoplanetary,
stellar, and
galactic evolution. In the context of
Gaia, these parameters provide insights into the
stellar populations, helping to trace the formation and history of the
Galaxy. As part of the
Gaia Data Processing and Analysis Consortium (DPAC), the Final Luminosity Age Mass
Estimator (FLAME) pipeline processes
Gaia data to derive
stellar parameters comprising luminosities, radii, masses and ages. This paper discusses the methods and data used in FLAME for
Gaia Data releases and the expected performances of FLAME for the 4th
Gaia Data Release. FLAME comprises two main components: the first one, which is analytical, is used to estimate luminosity, radius, and radial velocity correction due to gravitational
redshift by exploiting the atmospheric, astrometric, and photometric parameters produced within
Gaia. The second is a model inference based on two main approaches: a classical minimization approach, and a
Bayesian framework. It aims to derive mass, age, and evolutionary stage. The two step implementation offers flexibility in handling photometric properties that are prone to systematic errors. Tests with simulated data, the Sun, and well characterised samples of
stars show that the methods in FLAME perform as expected, producing results in statistical agreement with the literature. We provide new
stellar fundamental parameters for some high velocity
stars,
stars with very low mass companions, and a selection of
stars in the Plato Field of View. In
Gaia Data Release 4 approximately 500 million sources will have results from the pipeline. [abridged]
Read the full abstract ▾
All authors Orlagh L. Creevey, Laia Casamiquela, Yveline Lebreton, Christophe Ordenovic, Frederic Thevenin, Morgan Fouesneau, Rene Andrae, Coryn A. L. Bailer-Jones, Frederic Pailler, Bernard Pichon, Carine Babusiaux, Angelique Barbier, Nicolas Baudeau, Nathalie Brouillet, Santi Cassisi, Bengt Edvardsson, Oleg Kochukhov, Georges Kordopatis, Alessandro C. Lanzafame, Andreas Korn, Szabolz Meszaros, Camila Navarrete, Clement Robin, Rosanna Sordo, Caroline Soubiran, Daniel R. Reese
Statistical Mechanics · Cross-listed from q-bio.PE
Demographic senescence as multi-level selection in miniature
Ananda Shikhara Bhat and Hanna Kokko
Multi-level selection and senescence do not at first sight have much in common. Here, we demonstrate that the emergent mortality patterns generated by demographic senescence can be understood as the product of multi-level selection. We formulate a two-level Moran type process and use its scaling limits to illustrate that a simple mathematical framework that models multi-level selection in group-structured populations also models damage accumulation patterns and resultant mortality curves in ageing organisms. To verbally make the connection, observe that defectors spread within a group consisting of cooperators and defectors; when groups compete against each other, defector-rich groups suffer, and between-group selection causes such groups to be systematically under-represented. Exactly analogously, senescing individuals accumulate damage to physiological sub-systems, and `damage begets damage'; individuals who are more damaged are more likely to die, hence damage-rich individuals are systematically under-represented in later age classes. Thus, emergent senescence patterns in complex, integrated organisms are formally equivalent to the patterns generated by a within-generation multi-level selection process in which intra-organismal sub-systems play the role of particles, organisms play the role of collectives, and selective disappearance plays the role of group selection.
Read the full abstract ▾
Applied Physics · Cross-listed from eess.SP
ADC-Aware End-to-End Optimization of a Dynamic Metasurface Antenna with Strong Mutual Coupling for Monostatic Scene Classification
Philipp del Hougne
Dynamic metasurface
antennas (DMAs) enable programmable wave-domain signal processing that can be jointly optimized with downstream digital processing in an end-to-end manner. Existing studies, however, typically assume ideal analog-to-digital conversion (ADC) and often rely on simplified electromagnetic models. Here, we study ADC-aware end-to-end optimization of a monostatic sensing pipeline based on a DMA with strong mutual coupling (MC). We model the wave domain using an MC-aware multiport-network model whose parameters were experimentally estimated for a fabricated chaotic-cavity-backed DMA with 96 one-bit-programmable meta-elements. We perform ADC-aware end-to-end optimization of the DMA configurations and digital classifier, either with awareness of a fixed uniform ADC or, optionally, with jointly learned ADC decision thresholds, and compare against baselines that assume an ideal ADC and/or ignore MC. Our results show that ADC awareness is essential in low-resolution ADC regimes: with one-bit ADCs and eight DMA configurations, deploying an ideal-ADC-trained system with a uniform one-bit ADC reduces the test accuracy from 95.5% to 56.0%, whereas ADC-aware training with the same fixed uniform one-bit ADC achieves 87.2%. We also show that without MC awareness the accuracy drops to the random-guess level. Learning non-uniform ADC thresholds provides at most modest additional gains over fixed uniform ADCs in the considered DMA-based sensing pipeline.
Read the full abstract ▾
Materials Science
Anomalous bulk dealloying below the parting limit
Weiyue Zhou, Hooman Gholamzadeh, Lei Ding et al. (+9 more)
Dealloying has been extensively studied both as a corrosion degradation mechanism in structural materials, including those used in
nuclear, aerospace, or marine environments, and as a versatile method to fabricate porous materials for catalysts and other functional applications. Classical dealloying theory in aqueous environments predicts a critical reactive-element concentration (parting limit) for continuous selective dissolution at temperatures where bulk
diffusion does not dominate; this threshold is commonly reported around 50~60 at.%. Yet recent studies show that molten salt environments can generate extensive bulk dealloying below this threshold. Despite the importance of this anomalous dealloying behavior in many energy systems and electrochemical applications, its fundamental origin remains elusive. Here, we address this critical gap, revealing a grain boundary (GB)-assisted bulk dealloying mechanism. Using three-dimensional (3D) reconstruction of the dealloyed regions correlated with crystallographic and elemental analyses, we directly map the 3D GB-void architecture and reveal that
diffusion-induced recrystallization (DIR) generates a high-density GB network, which then promotes molten-salt infiltration and can drive bulk dealloying far-below the conventionally reported parting limit, producing a distinctive morphology reminiscent of discontinuous precipitation (DP). Understanding this dynamic GB-void interplay is crucial for the prediction and control of dealloying in complex electrochemical environments.
Read the full abstract ▾
All authors Weiyue Zhou, Hooman Gholamzadeh, Lei Ding, Kevin Daub, Mehdi Mosayebi, Travis Casagrande, Yingxin Zhu, Miaomiao Jin, Mark R. Daymond, Yang Yang, Michael P. Short, Suraj Y. Persaud
High Energy Physics (Phenomenology)
Soft-Dimuon Signature from Two-Component Scalar Dark Matter at the LHC
Alexander Belyaev, Manimala Chakraborti, Shu Chen et al. (+4 more)
We explore the potential of the Large
Hadron Collider to probe a two-component scalar dark matter scenario in the opposite-sign dimuon plus missing transverse energy final state, accompanied by a hard jet. The signal features a soft dimuon system with an invariant mass well below $m_Z$. We consider a 3-
Higgs Doublet Model with one active and two inert scalar doublets, where a $Z_2 \times Z_2'$
symmetry stabilises the lightest neutral scalar in each inert sector, yielding two scalar DM candidates. The relevant parameter space is mapped in terms of the two DM masses and the mass splittings between each DM candidate and its corresponding next-to-lightest scalar state. We perform a detector-level Monte Carlo analysis and design a dedicated cut-based selection, including a transverse-mass requirement adapted to the signal
topology. For a representative
benchmark, we obtain $S/B\simeq 9.8%$ and a statistical-only significance of $S/\sqrt{B}=1.35$ at Run 3 with ${\cal L}=300~{\rm fb}^{-1}$, increasing to $S/\sqrt{B}=4.93$ under a statistical-only extrapolation to ${\cal L}=4~{\rm ab}^{-1}$. Before the full selection, the two dark sectors generate a double-bump structure in the dimuon invariant-mass distribution. After the cuts optimised for inclusive sensitivity, however, this feature is not statistically robust enough to establish the two-component origin of the signal. The
benchmark is underabundant and is interpreted as a subdominant two-component DM scenario, while the
collider analysis remains independent of its cosmological abundance. Although the numerical study is carried out in the I(2+1)HDM, the results are applicable to weakly interacting sectors with similar electroweak associated production and cascade decays, where a heavier state separated from the DM candidate by less than $m_Z$ produces a soft
muon pair via an off-shell $Z$
boson.
Read the full abstract ▾
All authors Alexander Belyaev, Manimala Chakraborti, Shu Chen, Atri Dey, Venus Keus, Rakhi Mahbubani, Stefano Moretti
Physics and Society
Unequal Access to Power in Corruption Networks: Evidence from Colombia
Giovanna Rodríguez-García, María Elizabeth Mesa-Pineda and José R. Nicolás-Carlock
Corruption is embedded in networks of access, coordination, and protection, yet little is known about how gender shapes actors' positions within them. This article examines whether corruption networks in Colombia's territorial press reproduce gendered patterns of exclusion. Drawing on an access-to-power perspective, we argue that women's lower presence may reflect unequal incorporation into the spaces where exchanges are organized. Empirically, we use Transparencia por Colombia's Radiografía de Hechos de Corrupción, integrating case- and actor-level information to build co-participation networks. We analyze gender differences in composition, position, recurrence, and institutional access to resources. Results show that these networks are strongly masculinized: men dominate actors and ties, and women appear less often among recurrent actors. However, women are not absent from connected or dense areas, suggesting uneven rather than absolute exclusion. The findings shift
attention from whether women are ”less corrupt” to how unequal access to power structures participation in corruption networks.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Constraining leptonic and hadronic gamma-ray emission from HESS J1825-137 and its environment
Rubens Costa Jr. and R. C. Anjos
We present a broadband spectral analysis of the $\gamma$-ray emission from the
pulsar wind nebula HESS~J1825$-$137, combining observations from
Fermi Large Area
Telescope (
Fermi-LAT), High Energy Stereoscopic System (H.E.S.S.), High-Altitude Water Cherenkov Observatory (HAWC), and Very Energetic Radiation Imaging
Telescope Array System (VERITAS) across the $\sim 0.1$~GeV–$160$~TeV energy range. The spectral energy distribution is modelled under purely leptonic, purely hadronic, and lepto-hadronic scenarios using the Naima radiative modeling framework with Markov Chain Monte Carlo parameter estimation. Model comparison via the
Bayesian Information Criterion reveals that the baseline GeV–TeV data favour a purely leptonic interpretation, while the inclusion of simulated Cherenkov
Telescope Array Observatory (CTAO) observations or Large High Altitude Air Shower Observatory (LHAASO) ultra-high-energy (UHE; $E_{\gamma} \ge 100\,\mathrm{TeV}$) measurements shifts the preference toward models incorporating a hadronic component ($\Delta\mathrm{BIC} = -28.87$ and $-7.89$, respectively). The inferred electron energy budget for the baseline GeV–TeV
dataset, $W_e = 4.25 \times 10^{48}$~erg, is consistent with previous estimates reported in the literature. The
proton energy budget, $W_p \approx 2.5 \times 10^{48}$~erg, is energetically compatible with $pp$ interactions in the dense molecular environment adjacent to the nebula. These results demonstrate that precise spectral measurements above $\sim 10$~TeV, where Klein–Nishina suppression of inverse Compton emission creates a window for hadronic processes, are essential to establish the dominant emission mechanism in this source.
Read the full abstract ▾
Quantum Physics
Learning Low-Energy Subspace Overlaps in Many-Body Systems with Measurement-Based and Coherent Quantum Strategies
Shamminuj Aktar, Rishabh Bhardwaj, Tanmoy Bhattacharya et al. (+1 more)
Predicting the overlap of
quantum states with specified low-energy subspaces is a key diagnostic for
quantum many-body dynamics, with direct applications in state preparation, subspace-based
algorithms, and the study of thermalization. We study the supervised prediction of subspace overlaps O_K between time-evolved states and K-dimensional low-energy eigenspaces of a 10-
qubit Heisenberg
spin chain following a local perturbation. We compare two
quantum information extraction strategies: measurement-based learning, in which classical shadow features are processed by convolutional neural networks, and coherent
quantum learning, in which
quantum convolutional neural networks process the state directly. We further introduce physics-informed variants for both approaches, including
Hamiltonian-aware shadows and QCNN gates aligned with the Heisenberg exchange structure. Across five
dataset configurations spanning weak, moderate, and strong quench regimes, physics-informed QCNNs achieve stable performance, with mean test-set coefficients of determination R^2 = 0.753-0.846. Shadow-based methods show stronger regime dependence: they outperform QCNNs in the moderate-quench regime, reaching R^2 = 0.886, but underperform in weak and strong quenches at default shot budgets, where the best shadow results are R^2 = 0.615 and 0.672, respectively. Hardware validation on Quantinuum and IBM noise models shows that arbitrary state preparation is the dominant limitation, requiring approximately 2,044 two-
qubit gates and causing near-complete depolarization before inference. These results identify a regime-dependent tradeoff between measurement-based and coherent
quantum learning, with shadow methods excelling when the target remains locally accessible and physics-informed QCNNs providing more robust performance across dynamical regimes.
Read the full abstract ▾
All authors Shamminuj Aktar, Rishabh Bhardwaj, Tanmoy Bhattacharya, Stephan Eidenbenz
High Energy Physics (Phenomenology)
Production of Magic States via $Z$ Bosons and Dark Photons
Carlos Alvarado, Alfredo Aranda, César Bonilla et al. (+2 more)
The production of magic states is studied in two settings. The first is the electroweak (EW) sector of the Standard Model (SM). The second is an extension featuring a new broken $U(1)$ gauge
symmetry and a Dirac
fermion charged under it. This setup resembles a dark $U(1)$ scenario, with the additional
fermion playing the role of a dark matter candidate that annihilates into SM particles through its coupling to the new gauge
boson. In the EW sector, the low-energy regime reproduces earlier magic production results obtained for
Quantum Electrodynamics, whereas the high-energy and $Z$-resonance regimes generate new magic distribution functions and non-trivially reorganize the stabilizer state classes, with Bhabha scattering exhibiting the strongest sensitivity to electroweak effects. Also, a subset of fixed stabilizer states is identified, for which the magic distributions remain unchanged across the different energy regimes. In the dark sector, the main effect of the new massive mediator is the appearance of new magic distributions functions for Moller-like, Bhabha-like, and inverse pair-annihilation processes in the low-energy limit. These reach the maximal magic value at the SM-to-dark
fermion mass ratios $m_f/m_\chi \to 0$ and $m_f/m_\chi\to 1.83929$.
Read the full abstract ▾
All authors Carlos Alvarado, Alfredo Aranda, César Bonilla, Yahir Lua, Ethan Rodríguez-Martínez
Instrumentation and Methods for Astrophysics
Leveraging Multimodality for Real-Time Classification of Transients and Variables found by the Zwicky Transient Facility
Ved G. Shah, Nabeel Rehemtulla, Adam A. Miller et al. (+13 more)
Modern time-domain surveys such as the Zwicky Transient Facility (ZTF) generate hundreds of thousands of alerts each night, making real-time decisions for follow-up observations a central challenge in time-domain astronomy. Robust early classification is crucial for making informed decisions, but is hindered by sparse light curves and degeneracies between classes. In this work, we leverage multimodality to substantially improve real-time classification and demonstrate the practicality of our approach by deploying our model on the ZTF alert stream. Building on the Online Ranked Astrophysical CLass
Estimator (ORACLE), we introduce the ORACLE-2 models, which combine light curves, metadata, and images for real-time hierarchical classification. Using both real and simulated
datasets, we show that incorporating additional modalities consistently improves classification performance. On observations from ZTF's Bright Transient Survey, our best-performing model, ORACLE-2 Omni, achieves a macro F1 score of 0.73 – an improvement of up to 11% over models using light curves and metadata alone, and up to 40% over light-curve-only models, with the strongest gains realized at early times. To demonstrate applicability to the Legacy Survey of Space and Time, which will increase alert volume by more than an order of magnitude, we train a light curve + metadata variant on the simulated ELAsTiCC
dataset. This model achieves a macro F1 score of 0.88, an improvement of up to 13% over the light-curve-only variant, matching the performance of other state-of-the-art models. Finally, we quantify the trade-offs between performance and throughput, identifying regimes where
multimodal approaches offer the greatest benefit. These results show that combining multiple modalities improves early-time classification, enabling more effective triage of high-volume alert streams for current and future time-domain surveys.
Read the full abstract ▾
All authors Ved G. Shah, Nabeel Rehemtulla, Adam A. Miller, Sushant Sharma Chaudhary, Michael W. Coughlin, Antoine Le Calloch, Matthew J. Graham, Joahan Castaneda Jaimes, Theophile Jegou du Laz, Ashish A. Mahabal, Frank J. Masci, Josiah Purdum, Reed Riddle, Jesper Sollerman, Anastasia Wei, Mansi M. Kasliwal
High Energy Astrophysical Phenomena
Dense, multi-phase accretion disk atmosphere in the low-luminosity state of black hole transientV4641 Sgr
Zuobin Zhang, Rob Fender, James H. Matthews et al. (+11 more)
We present soft X-ray spectroscopy of the black-hole X-ray binary V4641~Sgr with the XMM-Newton Reflection Grating Spectrometer (RGS). The RGS spectrum shows narrow emission features from N\,vi–vii and O\,vii–viii superimposed on a partially covered disk blackbody continuum. A blind Gaussian search confirms the presence of significant lines at the expected rest wavelengths. He-like triplet ratios (high $G$, low $R$) and full photoionization modelling both indicate a dense, photoionized
plasma. Small redshifted velocities of $\sim 540$–$720\ \mathrm{km\ s^{-1}}$ are suggested, which are consistent with quasi-static or slowly flowing gas away from the observer after accounting for systematics. Photoionization modelling requires two xstar components with an intermediate ionization parameter ($\log\xi \simeq 3.1$) and a low ionization parameter ($\log\xi \simeq 0.36$), respectively. The simultaneous EPIC-pn spectrum suggests highly ionized Fe emission structures, hinting at an additional, more highly ionized component. These results imply the existence of a radially extended, multiphase, and dense disk atmosphere in the source. We compare the source with other X-ray binaries showing similar emission lines. V4641~Sgr shares a similarly high inclination with other sources; however, the presence of low ionization emission lines distinguishes it from the rest.
Read the full abstract ▾
All authors Zuobin Zhang, Rob Fender, James H. Matthews, Jiachen Jiang, Honghui Liu, Alessandra Ambrifi, Teo Muñoz-Darias, Maxime Parra, Megumi Shidatsu, Menglei Zhou, Yuexin Zhang, Abdurakhmon Nosirov, Cosimo Bambi, Justine Crook-Mansour
Instrumentation and Methods for Astrophysics
The Rubin Observatory Target-of-Opportunity System in the First Year of Operations
Sean Patrick MacBride, R. Lynne Jones, Peter Yoachim et al. (+41 more)
The NSF/DOE Vera C. Rubin Observatory is a discovery machine, with unprecedented survey speed, which can be used to identify exotic astrophysical transients. In its
prime mission, the ten year Legacy Survey of Space and Time will use 3% of its total time for Target of Opportunity observations, which includes response to gravitational wave events, high energy
neutrinos, potentially-hazardous asteroids, and other astrophysical phenomena. Target of Opportunity observations exist outside of the usual LSST operational mode, requiring special
attention to maximize performance. We review the Rubin Target of Opportunity system during its first year of Rubin Observatory operations, the Targets of Opportunity pursued since LSST first light, and the overall efficiency of the system.
Read the full abstract ▾
All authors Sean Patrick MacBride, R. Lynne Jones, Peter Yoachim, Tiago Ribeiro, Leanne P. Guy, Shreya Anand, Erin Leigh Howard, Ian S. Sullivan, Daniel L. Wang, Eric C. Bellm, Robert Armstrong, W. M. Wood-Vasey, Alex Drlica-Wagner, Kenneth Herner, Gautham Narayan, Tatiana Acero-Cuellar, Federica Bettina Bianco, Igor Andreoni, Bruno O. Sánchez, John Banovetz, Anastasia Alexov, Erik Dennihy, Robert D. Blum, Yousuke Utsumi, Marcelle Soares-Santos, Robert H. Lupton, Keith Bechtol, Željko Ivezić, Kris Mortensen, Paulina Venegas, Yijung Kang, Alysha B. Shugart, Narayan Khadka, Kshitija Kelkar, Danica Žilková, Kevin Fanning, Christopher W. Walter, Chris Weaver, Fabian Araneda-Baltierra, Andreja Gomboc, J. Anthony Tyson, Colin Orion Chandler, Pedro H. Bernardinelli, Devanshi Singh
Quantum Physics
Classification and Exact Local Masking in Finite-Field Clifford Dual-Unitary Circuits
Basanta R Pahari
We classify two-qudit Clifford dual-
unitary gates over the finite field $\mathbb{F}_q$, where the local dimension $q$ is a
prime power, and apply the classification to exact local masking and operator transport in homogeneous brickwork
circuits. Under ordered one-qudit Clifford equivalence, the dual-
unitary locus contains $q-2$ perfect-tensor cores, one rank-one core, and one SWAP core. Homogeneous repetition separates these cores into five distinct transport phases. The one-site Weyl edge channels determine exact local-masking distances. Writing $d_r(t)$ for the masking distance against output observers controlling at most $r$ sites, perfect-tensor
circuits attain \[ d_1(t)=4t, \qquad d_2(t)=4t-2, \] whereas delayed erasers satisfy \[ d_1(t)=4t-2, \qquad d_2(t)=4t-4 \] for $t\geq 2$. Consequently, sufficiently short
quantum messages are completely hidden from every one- or two-qudit output subsystem, even when the input is entangled with a reference, while remaining exactly recoverable from the full output. For $q=3$, we construct an explicit perfect-tensor Clifford gate from two inverse SUM gates. Exhaustive Weyl-support searches for $t=1,2,3$ reproduce the predicted masking distances. For a coherent perturbation of this gate, local leakage scales linearly with the perturbation strength, whereas the infidelity of recovery using the ideal inverse scales quadratically near the perfect point.
Read the full abstract ▾
Astrophysics of Galaxies
Precision near-IR spectroscopy for understanding AGN physics and shed light on the H0 tension – SHARP Science Book
M. Signorini, V. N. Bennert, E. Dalla Bontà et al. (+3 more)
The persistent tension between early- and late-Universe measurements of the Hubble constant (H0) remains on of the most significant challenges in modern cosmology. The Spectroastrometry and Reverberation Mapping (SARM) method offers a promising, calibration-independent approach to address this issue by combining time-delay measurements of the Broad-Line Region (BLR) with interferometric angular size determinations. Current implementations of SARM, however, are limited by the difficulty of performing near-infrared reverberation mapping (RM) on the same emission lines observed by
GRAVITY, restricting applications to only a few bright AGN. We propose using the capabilities of SHARP, the next-generation near-infrared spectrograph for the Extremely Large
Telescope (ELT), to overcome these limitations. SHARP's sensitivity and multi-object spectroscopy will enable (1) efficient long-term monitoring of existing
GRAVITY targets with minimal time investment, and (2) systematic RM campaigns for the fainter AGN that will be observed by
GRAVITY+. These advances will give us precise infrared lags for tens of AGN, enabling
geometric distance measurements and a robust, calibration-free determination of H0. Beyond cosmology, SHARP will allow detailed studies of BLR structure and kinematics in the infrared, advancing our understanding of AGN physics and with repercussion on the measurements of Supermassive Black Holes (SMBH) masses.
Read the full abstract ▾
All authors M. Signorini, V. N. Bennert, E. Dalla Bontà, F. Ricci, T. Treu, L. Villafaña
Astrophysics of Galaxies
The evolution of high-z proto-star clusters into local globular clusters
A. Della Croce, E. Vesperini, R. Pascale et al. (+4 more)
The James Webb Space
Telescope (JWST) detected numerous massive and relatively compact
stellar clumps around proto-
galaxies at high
redshift (z>0.5). Their properties suggest that these systems may represent proto-globular clusters (GCs), but their possible connection to local old GCs is poorly understood. In this Letter, we explore the dynamical
evolution of proto-
star clusters, building the missing evolutionary link between high-z systems observed by JWST and local GCs. Our simulations include the effects of
stellar interactions,
stellar evolution, and the strong time-dependent cosmological
tidal field in which these proto-
star clusters evolve. We also explore the role of multiple
stellar populations and
stellar-mass black holes (BHs), two fundamental ingredients in
stellar cluster dynamics. We show that systems hosting multiple populations (as routinely observed in local GCs) are more likely to endure the early strong
tidal field than single-population clusters. In addition, after 12 Gyr, such systems have properties consistent with those of
Galactic GCs. Our work confirms that the high-z clumps observed by JWST can be the progenitors of the local GCs. Finally, we show that a population of
stellar-mass BHs within a proto-
star cluster favors its disruption, but that surviving systems can retain a sizable population of BHs.
Read the full abstract ▾
All authors A. Della Croce, E. Vesperini, R. Pascale, A. Askar, F. Calura, E. Dalessandro, M. Giersz
Materials Science
Dominant-pair free energies predict phase selection in high-entropy alloys
Dennis Boakye and Chuang Deng
Phase selection in multicomponent
alloys is governed by the competition between entropic stabilization of disordered solutions and enthalpic driving forces for chemical ordering. However, widely used parametric criteria reduce it to a single scalar, carrying no explicit free energy for any competing ordered phase. Herein, we develop a thermodynamic framework based on the semi-empirical macroscopic atom model and the Dinsdale
lattice stability database to fill this gap. We show that a dominant-pair mechanism, in which the Al-transition-metal interaction family dominates the ordering enthalpy, enables the complex multicomponent B2-ordering problem to be reduced to an effective pseudo-binary system with an analytically evaluated Bragg-Williams free energy. Combined with a minimum-free-energy classifier, the framework predicts the lowest-energy phase as a function of composition and temperature. This provides continuous phase stability maps rather than the single-value predictions of conventional descriptors. Demonstrated on high-
entropy alloys using a
dataset of 269 experimentally characterized samples, the model outperforms widely used phase-selection criteria in the class-balanced macro-F1 metric and achieves 77.9% on the well-posed three-class task, outperforming the valence electron concentration criterion. The model is general by construction and computationally efficient for predicting phase stability in multicomponent
alloys over a broad range of compositions and temperatures.
Read the full abstract ▾
Earth and Planetary Astrophysics
Prospects for Panspermia via Interstellar Objects like 3I/ATLAS
Shokhruz Kakharov and Abraham Loeb
We study the feasibility of natural and directed panspermia via interstellar objects (ISOs) like 3I/ATLAS. The paper is organized around two questions. First, could natural panspermia occur if microbes or biomolecules survived inside shielded ice and were later exposed during perihelion and outbound activity? Second, could directed panspermia occur if a technological civilization planted life-bearing material inside or onto an icy ISO so that it later transported life through the Milky Way? We combine data on 3I/ATLAS with order-of-magnitude thermal, biological, and mission constraints. SPHEREx provides the volatile and organic context through CO$_2$, H$_2$O, CO,
dust, and a broad C–H feature, while JWST/MIRI provides the first direct CH$_4$ detection in an interstellar object and confirms an unusual volatile inventory, including enhanced CO$_2$:H$_2$O and CH$_4$:H$_2$O ratios. We distinguish dormant interstellar cruise from active perihelion. Natural panspermia is plausible as microbes can survive or repair damage in ice films, veins, or frozen
matrices at very low metabolic rates. Methane production is more nuanced. Frozen survival metabolism would require $\sim10^{14}$–$10^{15}$ kg of biomass to match the JWST CH$_4$ rates, but active methanogenic archaea in warm,
liquid, substrate-rich settings can produce methane many orders of magnitude faster, reducing the required biomass in optimistic laboratory-rate comparisons. Directed panspermia faces a different challenge: a direct 60 km s$^{-1}$ impact releases $1.8\times10^9$ J kg$^{-1}$, hundreds of times the specific energy of TNT, and would destroy a biological capsule. 3I/ATLAS-like objects are therefore best treated as test cases for panspermia diagnostics rather than as evidence for life. Natural panspermia requires preservation plus a credible
liquid-water or near-surface activation pathway.
Read the full abstract ▾
Atomic Physics
New Bounds on Exotic Long-Range Spin-Spin Interactions
Nathan B. Clayburn, Andrew Glassford, Thomas Uelmen et al. (+8 more)
Many proposed extensions to the Standard Model of particle physics introduce new
bosons that can mediate forces which couple to particle
spin. Here we describe a search for such forces coupling
spin-polarized
neutrons and
protons in our magnetometer to
spin-polarized electrons within Earth. We measure these interactions by varying the orientation of an optical $^{199}$Hg-$^{133}$Cs free-precession comagnetometer mounted upon a precision rotation platform. From these measurements, we establish upper bounds on the dimensionless coupling constants associated with the axial-axial potential $V_2$ and the axial-vector potential $V_{11}$ as a function of the force's range $\lambda$. For the electron-
neutron and electron-
proton potential $V_2$ at infinite range, we find $|g_A^eg_A^n| \leq 3.0 \times 10^{-48}$ and $|g_A^eg_A^p| \leq 3.0 \times 10^{-47}$. For $V_{11}$, we find our most stringent bounds to be $|g_A^eg_V^n| \leq 2.2 \times 10^{-25}$ and $|g_A^eg_V^p| \leq 2.2 \times 10^{-24}$ at $\lambda \approx 10^3$ km. Our results represent an improvement over previous results by up to a factor of 17 and set the most stringent bounds on long-range axial-axial and axial-vector couplings between electron
spins and
neutron and
proton spins.
Read the full abstract ▾
All authors Nathan B. Clayburn, Andrew Glassford, Thomas Uelmen, Ashley R. Kyung, Yana Boneva, Saif Salim, Alison S. Weiss, Flanagan Waldherr, Claire Carlin, Stephen K. Peck, Larry R. Hunter
Fluid Dynamics
A High-Order Arbitrary Lagrangian-Eulerian Discontinuous Galerkin Method for the Boltzmann Equation in Nearly Incompressible Flows
Atakan Aygun, Onur Ata, Tim Warburton et al. (+1 more)
We propose the arbitrary Lagrangian-Eulerian (ALE) form of the Galerkin-Boltzmann formulation for the simulation of nearly incompressible flows with moving boundaries. The continuous Boltzmann equations are mapped to a reference state to compensate the mesh motion with an advection term. The resulting system is discretized in space using the discontinuous Galerkin method on unstructured meshes. A semi-analytic Runge-Kutta time discretization is used to overcome the stiffness introduced by the continuous Boltzmann equations. The well-known
geometric conservation law is shown to be satisfied by the time and space discretizations and consistent update of
geometric factors of the discretization. The implementation is on the GPU accelerated kernel library libParanumal and validated by a free stream preservation and moving Taylor-Green
vortex test cases. Then, the capabilities are shown using a plunging symmetric airfoil in two-dimensions and moving carangiform fish in three-dimensions using perfectly matched layers.
Read the full abstract ▾
All authors Atakan Aygun, Onur Ata, Tim Warburton, Ali Karakus
Quantum Physics
Wavefunctions localization, and the Wigner's Friend Paradox in a Framework of Discrete-Space Hypothesis
W. A. Zúñiga-Galindo
We present a resolution of the Wigner's Friend paradox within a framework of
quantum mechanics (QM) on the hybrid space RxQ_{p}, where Q_{p} denotes the field of p-adic numbers, regarded as a model of discrete microscopic space at the Planck-Bronstein scale. In this framework, wavefunction collapse is not an independent postulate but a dynamical consequence of the Schrödinger equation with non-local
Hamiltonians: wavefunctions localize onto compact supports during measurement interactions, producing definite pointer readings without the intervention of observers or the exchange of information between subsystems. We model both Wigner and his Friend as classical apparatuses and show that each produces a definite reading through independent applications of the collapse mechanism, thereby eliminating the conflict between their descriptions of reality. The framework is consistent with the principal no-go
theorems in finite- and infinite-dimensional
Hilbert spaces associated with extended Wigner's Friend scenarios – including those of Frauchiger-Renner, Brukner, Bong et al., and Guérin et al. – since it requires no
agents capable of recording or
reasoning about outcomes, thereby vacating the observer-dependent assumptions that drive those
theorems. We illustrate the collapse mechanism explicitly through a toy model of a particle in a box, comparing the standard description with the new one. The non-locality intrinsic to QM on L2(RxQ_{p}) permits realism at the cost of locality, and the Absoluteness of Observed Events holds in our framework without requiring observer independence.
Read the full abstract ▾
Materials Science
Structure-Dependent Chemical Order Modification in Strained Alloy Nanoparticles
Yue Wang, Zibo Chen, Evropi Toulkeridou et al. (+2 more)
Alloy nanoparticles (nanoalloys) exhibit tuneable physicochemical properties that depend sensitively on their atomic arrangement, making control over chemical ordering a central challenge in nanomaterials design. While most theoretical studies consider nanoalloys in
vacuum, practical systems are typically supported, where strong cluster-substrate interactions can introduce significant
lattice strain. Here, we investigate strain as a control parameter for chemical ordering in bimetallic nanoalloys using atomistic molecular dynamics and Monte Carlo simulations. By imposing controlled tensile and compressive strain through an implicit anchored interface, we systematically probe the response of NiPt nanoparticles with distinct structural motifs. For truncated octahedral particles, we find that chemical ordering and segregation behaviour remain remarkably robust even under large strains, indicating that intrinsic thermodynamic preferences dominate. In contrast, icosahedral nanoparticles exhibit pronounced strain-induced chemical redistribution, with a significant increase in surface Ni concentration under tensile strain. This behaviour is attributed to the combined effects of intrinsic
geometric frustration and a high fraction of undercoordinated sites in icosahedral structures. Our results demonstrate that strain can selectively modulate chemical ordering in nanoalloys in a structure-dependent manner, establishing a general framework for understanding strain-induced chemical ordering in nanoalloys.
Read the full abstract ▾
All authors Yue Wang, Zibo Chen, Evropi Toulkeridou, Joseph Kioseoglou, Panagiotis Grammatikopoulos
Quantum Physics
TCL4 Asymptotic Redundancy and Canonically Consistent Master Equations
Dragomir Davidovic
Left alone, open
quantum systems relax toward a Kubo–Martin–Schwinger (KMS)
equilibrium state, yet the inner workings of this process remain opaque. It remains unclear why the intricate fourth-order time-convolutionless (TCL4) population generator reproduces the comparatively simple second-order stationary state corrections. Even more surprisingly, stationary-state corrections of such precision can be compressed into a simple virtual coherence pathway: an open
quantum systems analogue of virtual transitions, in which populations communicate through coherences that are never occupied. Here we show that this simplification arises through a sequence of stationary-state-preserving transformations that progressively eliminate asymptotically redundant components while preserving the stationary state, ultimately yielding the virtual coherence pathway. This resolves the longstanding stationary-state problem of the Redfield equation and reveals that much of the apparent complexity of the TCL4 generator is asymptotically redundant.
Read the full abstract ▾
Solar and Stellar Astrophysics
Spectroscopic Monitoring of Metal Lines in Polluted White Dwarfs
Laura K. Rogers, Michael M. Shara, Amy Bonsor et al. (+12 more)
The disruption and
accretion of planetary material onto white
dwarfs is expected to be inherently dynamic and
stochastic, potentially driving variability in the
accretion rate and therefore the shape and depth of the photospheric metal absorption lines. This paper presents an 18-year optical spectroscopic monitoring campaign of five warm (11,000-23,000K) polluted white
dwarfs with sinking timescales of days-months, observed using Magellan/MIKE and SALT/HRS to directly test this prediction. At four of the five systems, no statistically significant variability is detected over baselines of 15-18 years corresponding to hundreds to thousands of
diffusion timescales, with inferred
accretion rates stable to within 15-30% (1$\sigma$) showing remarkably stable
accretion on decadal timescales. This implies that either the processes maintaining the
accretion of the disrupted planetary material are stable on the same timescales, or that currently uncharacterized photospheric processes act to smooth observable abundance variations on these timescales. The one exception, WD 0106$-$328, shows statistically significant variability in the 4481A Mg II doublet from the ground-based data. Yet no significant equivalent width or abundance changes are seen between two Hubble Space
Telescope ultraviolet spectra taken in 2016 and 2025, despite probing a larger set of transitions. This may imply that the ground-based observations witnessed a
stochastic excursion from a stable baseline
accretion rate, rather than a sustained change in the bulk
accretion rate.
Read the full abstract ▾
All authors Laura K. Rogers, Michael M. Shara, Amy Bonsor, Siyi Xu, Érika Le Bourdais, Patrick Dufour, John Debes, Omri Nolan, Ted von Hippel, Erik Dennihy, Simon Hodgkin, Andrew Swan, Mariona Badenas-Agusti, Mark C. Wyatt, Tim Cunningham
High Energy Physics (Theory)
From geometry to phenomenology
Stefan Weinzierl
Precision calculations in
quantum field theory rely very often on perturbation theory and thus on the computation of Feynman integrals. Feynman integrals are also fascinating objects from a mathematical point of view and show deep connections to algebraic geometry. Cutting-edge Feynman integrals usually have geometries of "mixed" type, for example parts of it may correspond to a K3-surface, other parts may correspond to curves of a certain genus and the simplest parts correspond to points. In this talk I will discuss how to extract the
geometric information from a Feynman integral and how this information can be used to compute more efficiently Feynman integrals. Non-trivial mixed geometries already occur in $2 \rightarrow 2$-processes at two-loops, like Drell-Yan, Bhabha and Moller scattering.
Read the full abstract ▾
Quantum Physics
A universal time-of-arrival signature of Bose–Einstein condensation
Mathieu Beau and Timothey Szczepanski
We show that Bose–Einstein condensation produces a cusp in the time-of-arrival (TOA) statistics of a harmonically trapped gas released into free fall. In the semiclassical long time-of-flight regime, with $\epsilon=\sigma_V/\sqrt{2gH}\ll1$, both the mean and standard deviation of the arrival time distribution, which are governed by the longitudinal velocity variance, remain continuous, but acquire a cusp whose one-sided slope ratio is universal within the ideal-gas far-field limit, $\mathcal{R}_\infty=2.5556\ldots$, and equals the trapped-gas specific-heat ratio $C(Tc^-)/C(Tc^+)$. Finite atom number rounds the cusp and weak interactions perturb it only weakly, leaving a measurable time-domain signature of condensation.
Read the full abstract ▾
High Energy Physics (Experiment)
High-mass new scalars at the LHC, with H in the final state
Andre Sopczak
The search for new particles, conducted at the LHC by the ATLAS and CMS collaborations, covers several production and decay modes, leading to a large variety of final states that could be observed in both detectors. This review focuses on the production of new heavy scalars that have a
Higgs boson in the final state. Three cases are covered: resonant production of a heavy scalar $X$ decaying into a
Higgs boson and a lighter scalar $S$, heavy neutral
Higgs boson decaying into another neutral
Higgs boson and a $Z$
boson, and a heavy charged
Higgs boson production with subsequent decay into another neutral
Higgs boson and a $W$
boson. The reviewed searches are based on the complete LHC Run-2
dataset and partial Run-3
dataset.
Read the full abstract ▾
Physics and Society
Synchronization and Swarming of Two-Mode Stochastic Oscillators
Szabolcs Vitus and Ferenc Járai-Szabó
Synchronization and swarming are canonical manifestations of self-organization, observable across scales from cellular processes to animal flocks. This study investigates the collective dynamics of a novel
agent-based model where individuals exhibit both spatial mobility and internal, two-mode
stochastic oscillatory states. By introducing a local, distance-dependent coupling between the
agents' spatial configuration and their internal state transitions, we establish a mutual feedback loop that drives complex pattern formation. Through large-scale numerical simulations, we identify seven distinct morphological configurations, ranging from stationary Filled-disk states to highly disordered Intense-motion regimes. By performing a rigorous quantitative analysis of the rotational energy and radial dispersion, we transcend simple morphological classification and demonstrate that the system organizes into discrete, quantized topological attractors. We derive a macroscopic scaling law, $\Omega \propto r^{-1/2}$, which proves that the emerging rotating states are not rigid-body rotations, but rather composite differential
vortex structures characterized by spontaneous
chiral symmetry breaking. Our results suggest that these stable, quantized dynamical states are fundamental features of systems governed by bidirectional spatial-phase feedback, offering a robust framework for designing autonomous, decentralized robotic swarms.
Read the full abstract ▾
Computational Physics
A Scoping Review of Physics Informed Machine Learning for Wave Propagation Modeling in Seismology
Óscar Rincón-Cardeño, Gregorio Pérez-Bernal, Silvana Montoya-Noguera et al. (+1 more)
Standard numerical methods accurately simulate seismic waves but are computationally expensive, particularly for inverse problems. Some machine-learning-based alternatives have emerged, promising to reduce cost while preserving physical accuracy. This scoping review, drawing on OpenAlex and Scopus, maps physics-informed machine learning applications to seismic wave propagation based on partial differential equations, classifying selected studies by problem type (forward or inverse) and learning strategy to uncover trends, patterns, and gaps. Results show that these methods have been applied to both forward modeling and inversion, often matching standard numerical accuracy at lower cost. We identified three mechanisms for incorporating physical knowledge into models: observational, inductive, and learning bias. We implemented a PyTorch replication of the original PINN framework to test methodological reproducibility of a representative method, obtaining results consistent with and, in most cases, more accurate than those originally reported. Based on the reviewed literature, we identified limitations in benchmarking consistency, training cost, and scalability to three-dimensional and experimentally validated problems. We conclude that while standard numerical methods remain foundational, physics-informed machine learning serves as a complementary tool valuable for inverse problems and surrogate modeling, with future work needing consistent benchmarking, hybrid formulations, and validation under realistic geophysical conditions. The continued development of these methods, particularly through hybrid formulations and reproducible benchmarking, may broaden their role in seismological workflows, although realizing this potential will need addressing current limitations in scalability.
Read the full abstract ▾
All authors Óscar Rincón-Cardeño, Gregorio Pérez-Bernal, Silvana Montoya-Noguera, Nicolás Guarín-Zapata
Quantum Physics
Superconducting Spiral Inductors for RF Reflectometry: Operation at Elevated Temperatures and Magnetic Fields
Euan Parry, Murat Cubukcu, Patrick Reuvekamp et al. (+3 more)
Superconducting spiral inductors are emerging as key components for
radio-frequency (RF) reflectometry, a widely used readout technique for
semiconductor spin qubits. Future scalable
quantum-computing architectures are expected to operate at elevated temperatures and
magnetic fields, placing new demands on the performance and stability of superconducting
circuit elements. Here, we present a systematic study of NbTiN spiral inductors under temperatures of several kelvin and
magnetic fields approaching 1 T. By combining weakly coupled resonator measurements with independent two-port inductance extraction, we separate inductive and capacitive contributions to device behaviour and directly identify the origin of resonance shifts and quality factor degradation. Furthermore, we establish practical design metrics linking geometry, temperature sensitivity, and
magnetic-field robustness. These results provide a general framework for benchmarking superconducting inductors and guiding the design of future RF-reflectometry
circuits for practical
quantum technologies.
Read the full abstract ▾
All authors Euan Parry, Murat Cubukcu, Patrick Reuvekamp, Manoj Stanley, Jonathan D. Fletcher, Alessandro Rossi
Disordered Systems and Neural Networks · Cross-listed from cs.LG
Scaling Up Thermodynamic AI Models
Andrew G. Moore
Thermodynamic computing devices based on the Ising model show great promise for low-power AI inference and edge computing, but scalable methods for training large models for such hardware remain limited. Prior theory shows that the time-averaged behavior of high-temperature Gibbs-sampled Ising systems can implement feed-forward neural inference. We turn this theoretical correspondence into a scalable and purely backpropagation-based
algorithm for training deep convolutional networks for thermodynamic inference on Ising machine hardware. Our image classification models achieve accuracies of 94.9% on CIFAR-10 and 76.0% on CIFAR-100 under binary Gibbs sampling. We then develop and experimentally validate a mathematical theory relating inference cost to accuracy and controlling autocorrelation times. Subsequently, we calculate asymptotic results showing that inference cost is bounded by a well-controlled tradeoff with performance and exhibit
algorithms for computing optimal inference schedules. Finally, we discuss implications for hardware development and the future of high-temperature thermodynamic AI models.
Read the full abstract ▾