General Relativity and Quantum Cosmology
Cosmological implications of f(T, B) gravity: constraints from recent observations
Laxmipriya Pati, Santosh V. Lohakare and S. K. Maurya
In this work, we examine the theoretical framework of modified teleparallel
gravity with the inclusion of the boundary term in the action and investigate its cosmological implications by considering the power-law model $f(T, B) = -T + \alpha (-B)^{\beta}$, with the aim of addressing the late-time accelerated expansion and the dark energy. In this context, $T$ denotes the torsion scalar and $B$ represents the boundary term, whose presence allows for departures from standard teleparallel dynamics and provides a unified description that connects torsion and
curvature-based formulations, reproducing $f(T)$ and $f(R)$
gravity in appropriate limits. The viability of the model is assessed by confronting its theoretical predictions with observational data while constraining the cosmological and model parameters through a Markov Chain Monte Carlo (MCMC) analysis using
cosmic chronometers (CC), the Pantheon Plus sample (PPS), and the DESI
baryon acoustic oscillation (BAO) Data Release 2 (DR2)
datasets, and comparing its performance with the standard $\Lambda$CDM model. The Akaike Information Criterion (AIC) analysis shows that the combined CC+PPS
dataset strongly favors the $f(T, B)$ model, suggesting an improved phenomenological fit to late-time observations relative to $\Lambda$CDM. Our result further shows an alleviation of H0 tensions, although a dedicated analysis is required to establish its full statistical significance. Furthermore, the background cosmological quantities indicate that the model exhibits a dynamical phantom-divide crossing while remaining consistent with late-time observations and yielding a viable expansion history and characteristic dark energy
evolution.
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Astrophysics of Galaxies
How can we finally see the first light? Status and perspective in the search for Population III stars
Alessandra Venditti, Daniel Schaerer, Erik Zackrisson et al. (+26 more)
Finding the first (Population III or Pop III)
stars is one of the fundamental quests of astronomy, aiming to deliver the missing link in how
stars form at early
cosmic times. Yet their initial mass function, formation sites and feedback remain highly uncertain, as well as the timing and
topology of the transition to metal-enriched
star formation. The observability of their peculiar spectral features is also debated, due to their short lifetime and faintness. This review summarizes current theoretical expectations for Pop III
star formation, and the main observational strategies that have been adopted to constrain their properties across
cosmic time, including near-field cosmology studies, direct searches for extremely metal-poor
star-forming complexes and/or hard-ionizing spectral signatures at high and intermediate
redshifts, and prospects for identifying Pop III activity up to
Cosmic Dawn. The combination of JWST spectroscopy, time-domain searches,
lensing surveys,
stellar archaeology, absorption-line studies, as well as improved simulations, is yielding a growing number of observational candidates and narrowing the allowed parameter space for the first
stars, setting the stage for a “golden era” of Pop III searches.
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All authors Alessandra Venditti, Daniel Schaerer, Erik Zackrisson, Yoshihisa Asada, Harley Katz, Stefania Salvadori, Eros Vanzella, Julian B. Muñoz, Anatole Storck, Andrew J. Bunker, Alessandro Trinca, Dirk Scholte, Fabio Pacucci, Pablo G. Pérez-González, Seiji Fujimoto, Corinne Charbonnel, Roberto Maiolino, Andrea Ferrara, Mauro Giavalisco, Raffaella Schneider, Josephine Baggen, Hakim Atek, Volker Bromm, Karina Caputi, Laure Ciesla, Pratika Dayal, Chiaki Kobayashi, Marco Castellano, Paola Santini
Chemical Physics
Irreducible Representations as Multireference Indicators for Diradicaloid Systems
Emmalyn A. Sarver and Lukas Muechler
Multireference behavior in molecules often arises when a small gap between frontier orbitals results in mixing of closed and open-shell configurations. Standard multireference diagnostics of this regime usually rely on correlated wavefunctions, natural-orbital occupations, or reduced density
matrices. Here, we examine a complementary,
symmetry-based criterion for a model system. For a time-reversal-invariant
Hamiltonian, a
symmetry-preserving, closed-shell Slater determinant must transform as the trivial irreducible representation of its point group. Therefore, a nontrivial, many-electron irreducible representation excludes such a description. We compare two pathways within the same model to demonstrate this. Along the control pathway, the frontier orbitals remain separated and the ground state retains a trivial irreducible representation over the weak-to-intermediate interaction regime. Along the obstructed pathway, a high-
symmetry point produces a frontier-orbital degeneracy, resulting in a singlet ground state with two-configuration character and a nontrivial irreducible representation. Exact diagonalization, a two-state effective model, and the Frobenius norm of the two-particle cumulant provide a consistent picture in this regime, demonstrating that irreducible representations can serve as a low-cost diagnostic of multireference character in diradicaloid models. While
symmetry is not a quantitative measure of correlation strength, it does offer a computationally inexpensive screening tool to identify obstructions to a single-reference description.
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Astrophysics of Galaxies
Far-infrared observations of dust in Ly$\alpha$ emitters at z=2-6
Rahul Rana, Julie L. Wardlow, Thomas M. Cornish et al. (+3 more)
The bright Ly$\alpha$ line is regularly used to identify high-
redshift star-forming
galaxies known as Ly$\alpha$ emitters (LAEs). However, Ly$\alpha$ is affected by resonant scattering and
dust absorption making interpretation of its brightness challenging without additional observations. We use SCUBA-2, PACS and SPIRE data to investigate the far-infrared emission, Ly$\alpha$ escape fraction ($f{esc}$(Ly$\alpha$)) and infrared excess (IRX=LIR/LUV) in $\sim$4000 LAEs at z=2.2-6 from SC4K. Five LAEs, all hosting AGN, are individually detected with fluxes $S_{850}$ = 3.7-5.5 mJy at 850$\mu\mathrm{m}$. Stacking is used to probe the average emission from all individually undetected LAEs, though the stacks are undetected at all wavelengths (e.g. $S_{850}$ < 0.09 mJy; 3$\sigma$). We group the sample into bins of
redshift,
stellar mass, Ly$\alpha$ luminosity and AGN status. Most subsets are undetected but LAEs containing AGN and that have high
stellar masses ($M_{\star} = 10^{10} - 10^{12}\, M_{\odot}$; including and excluding AGN) are detected at most wavelengths, suggesting that
stellar mass and AGN heating may be enhancing the
dust visibility. Individually detected LAEs and detected stacks have $f{esc}$(Ly$\alpha$)=1-7%, while all undetected stacks $\geq$ 10%. All LAEs together average over > 21% and display significant scatter, suggesting a clumpy ISM
dust distribution. Non-zero $f{esc}$(Ly$\alpha$) in massive and AGN-hosting LAEs suggests ionizing
photons may escape even from dusty
galaxies, challenging the idea that dusty
galaxies are poor leakers. Examination of the IRX-$\beta_{UV}$ relation shows LAEs have higher IRX than typical
star-forming
galaxies at similar
redshifts. However, our detections tend to favour more massive, AGN-hosting systems and deeper observations are therefore needed.
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All authors Rahul Rana, Julie L. Wardlow, Thomas M. Cornish, Pascale H. Desmet, David Sobral, João Calhau
Instrumentation and Methods for Astrophysics
Rubin M1M3 Dynamic performance : stability and actuation during operations
HyeYun Park, Petr Kubánek, Kshitija Kelkar et al. (+20 more)
The Vera C. Rubin Observatory is preparing to commence the Legacy Survey of Space and Time with the fully integrated Simonyi Survey
Telescope. To verify that the primary/tertiary (M1M3) mirror system is ready to meet the demanding survey requirements, dynamic tests of the 8.4 m, 53 ton M1M3 system were conducted to assess safety, stability, and image quality under realistic operating conditions. The M1M3 is supported by 156 pneumatic force actuators and positioned, relative to its mirror
cell, by six hardpoint actuators that together must counteract gravitational and inertial loads during rapid
telescope motion. The Rubin Observatory
telescope mount is capable of moving at a rate that meets its nominal motion requirements, and can approach it maximum allowable values that are 50 percent higher. Even at just 20 % of its operational speed, it is an exceptionally fast motion for such a large structure. After slewing, the system must stabilize and dampen vibrations within 5 seconds to ensure image quality during observations. Achieving this rapid settling requires precise control of 156 force actuators, which must adjust dynamically with changes in
telescope elevation to compensate for
gravity effects. We present results for M1M3 from a comprehensive series of TMA dynamical tests spanning the operational envelope of slew velocities and accelerations. The analysis evaluates elevation axis balancing and lookup table updating as we install the M1M3 mirror; slew-and-settle behavior, force response and stability of the pneumatic actuator system across
telescope attitudes including responses to the earthquake. The results demonstrate the readiness of the M1M3 subsystem for routine survey operations and provide validation data for ongoing performance modeling.
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All authors HyeYun Park, Petr Kubánek, Kshitija Kelkar, Ignacio Sevilla-Noarbe, Andrea Jeremie, Brian Stalder, Bruno C. Quint, David Sanmartim, Dominique Boutigny, Douglas R. Neill, Erik Dennihy, Felipe Daruich, Freddy Muñoz Arancibia, Kevin Fanning, Kevin Reil, Laura Toribio San Cipriano, Malhar Sonaniskar, Marina S. Pavlovic, Noah Gonzalez, Paulina Venegas, Sandrine Thomas, Tiago Ribeiro, Yijung Kang
Materials Science
Topological Hall plateau in quasi-2D kagome magnet YMn$_6$Sn$_6$
Sambit Jena, Nastaran Salehi, Manuel Pereiro Lopez et al. (+5 more)
We examine the impact of the Dzyaloshinskii–Moriya interaction (DMI) in kagome magnets and show that a predominantly planar DMI together with
ferromagnetic exchange stabilizes a disordered skyrmion phase in quasi-two-dimensional (2D) YMn$_6$Sn$_6$. Within an {\it{ab initio}} framework combining density functional theory and
spin-dynamics simulations, we generate realistic
spin textures of disordered skyrmion and find that this phase persists for $B_{\rm ext} \leq 0.5$~T, with a decreasing skyrmion size as
magnetic field increases. We demonstrate the emergence of topological
Hall plateau in the range $-0.5 \leq B_{\mathrm{ext}} \leq 0.5$~T, driven by nearly uniform scalar
spin chirality and the resulting constant real-space Berry
curvature. This response is anti-symmetric with
magnetic field while magnitude and sign of these plateau are determined by a complex interplay between Hund's coupling strength and chemical potential signifying the role of Dirac points and van Hove singularities. In addition, we reveal topological
magnon excitations in the disordered skyrmion phase of quasi-2D YMn$_6$Sn$_6$.
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All authors Sambit Jena, Nastaran Salehi, Manuel Pereiro Lopez, Olle Eriksson, Narayan Mohanta, Karthik V Raman, Tanay Nag, Banasree Sadhukhan
General Relativity and Quantum Cosmology
Cosmology with a Non-minimally Coupled Dark Matter Fluid II. Cosmological Perturbations
Samuele Silveravalle, Andrea Lapi, Francesco Benetti et al. (+1 more)
We extend our study of a cosmological scenario in which dark matter is non-minimally coupled to
gravity at the fluid level. In previous work, we showed that this interaction can drive an early phase of accelerated expansion, addressing the horizon and flatness problems, and can also lead to a cosmological bounce in the presence of negative spatial
curvature. Here we analyse the
evolution of linear perturbations in this framework. We derive the equations governing scalar, vector and tensor perturbations, and obtain analytic solutions in the relevant cosmological regimes. We find that perturbations generated during the accelerated expansion phase produce a strongly blue scalar power spectrum and are therefore incompatible with observations. By contrast, if
primordial fluctuations are generated during the contracting phase of a bouncing solution, the model yields an approximately scale-invariant scalar power spectrum while keeping the tensor-to-scalar ratio compatible with current bounds. Although our treatment relies on simplifying approximations that should be refined in future work, these results indicate that an observationally viable
primordial spectrum can be obtained only with a bouncing solution, and hence with a non-singular early-time
evolution.
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All authors Samuele Silveravalle, Andrea Lapi, Francesco Benetti, Stefano Liberati
High Energy Physics (Phenomenology)
The left-cut for partial waves in terms of physical amplitudes
Alexandre Salas-Bernárdez
We derive a novel representation of the partial wave amplitude over the left-hand cut for $2 \to 2$ scattering. We express the left-hand cut of arbitrary isospin and angular momentum partial waves as an integral of right-hand cut imaginary parts. This formulation provides an explicit, exact extraction of the logarithmic branch cut structures, offering a valuable tool to systematically quantify left-hand cut uncertainties in unitarization methods such as the Inverse Amplitude Method or $N/D$ approaches.
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High Energy Astrophysical Phenomena
Anomalous Air Showers and What They Reveal About Hadronic Interactions and Cosmic-ray Masses
Stijn Buitink, Vital De Henau, Sjoerd Bouma et al. (+28 more)
The identification of the sources and acceleration mechanisms of
cosmic rays require precise measurements of their mass composition. Currently, the most reliable method is to measure the atmospheric depth at which
cosmic ray air showers in our atmosphere reach their maximum (\Xmax). However, the hadronic interaction properties that govern the longitudinal development of air showers are not precisely known, which is a major source of systematic uncertainty on the mass composition. SKA-Low will observe
cosmic rays in the 10$^{16}$ - 10$^{18}$ eV energy range with unprecedented resolution and bandwidth. This allows for a much more detailed reconstruction of the longitudinal shower
evolution, which can be used to gain better understanding of the hadronic interactions, as well as the primary mass composition. After the first interaction of the
cosmic ray with an atom in an air molecule, the secondary particles still carry a significant fraction of the total energy. When one of these particle travels very far before interacting again, it produces a sub-shower that can be recognized as a secondary bump in the longitudinal profile. Simulations have demonstrated that SKA-Low can resolve such double bump profiles by virtue of its high
antenna density and broad bandwidth. In this chapter, we demonstrate how double-bump showers and other anomalous longitudinal developments can be used to constrain hadronic interaction properties, and to determine the mass composition of
cosmic rays in the
Galactic-to-extragalactic transition region.
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All authors Stijn Buitink, Vital De Henau, Sjoerd Bouma, Justin Bray, Arthur Corstanje, Edwin Dickinson, Brian Hare, Andreas Haungs, Haoning He, Jörg Hörandel, Tim Huege, Clancy James, Philipp Laub, Xingyu Li, Hermann-Josef Mathes, Katharine Mulrey, Anna Nelles, Subhadip Saha, Felix Schlüter, Olaf Scholten, Ralph Spencer, Christopher Sterpka, Karen Terveer, Satyendra Thoudam, Gia Trinh, Paulina Turekova, Darko Veberic, Keito Watanabe, Chao Zhang, Pengfei Zhang, Yi Zhang
Strongly Correlated Electrons
Gibbs-state phases beyond microscopic symmetry breaking: A phase invariant for the 3D toric code
Haruki Watanabe
Do phases of Gibbs states admit a classification beyond
symmetry breaking? We study the three-dimensional toric code with transverse and longitudinal fields that explicitly break both microscopic higher-form
symmetries. We introduce the connected correlation $f_W$ of two locally decoded winding Wilson loops. Nonzero asymptotic $f_W$ rules out shallow local preparation from product states. An asymptotic optimization over the observables and physical recovery channels defines an invariant $\mathcal{F}$, which we prove constant within phases defined by two-way local channels with product ancillas and sublinear causal radius. The invariant equals one for the canonical zero-temperature state of the field-free toric code.
Quantum Monte Carlo tests the conjectured thermodynamic values $f_W=1$ at weak fields and low temperature and $f_W=0$ elsewhere. The fixed-decoder correlation provides a lower bound on $\mathcal{F}$, so the results suggest an extended region with $\mathcal{F}=1$. Product states, including the infinite-temperature state and fully polarized infinite-field limits, have $\mathcal{F}=0$ exactly and therefore lie in a different phase from states with $\mathcal{F}=1$.
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General Relativity and Quantum Cosmology
Modified Cosmology from Mass-to-Horizon Relation: Background Evolution
Pranav Prasanthan, Hussain Gohar and Vincenzo Salzano
We investigate the cosmological implications of the mass-to-horizon relation, which provides a unified framework for thermodynamically consistent generalized horizon-
entropy functionals. Using the Cai-Kim formulation of the first law of thermodynamics, we derive the corresponding modified Friedmann equations and examine the resulting background
evolution. We find that cosmological viability sharply restricts admissible deviations from the Bekenstein-Hawking area law: phenomenologically acceptable scenarios are confined to a narrow neighborhood of the standard
entropy, while more pronounced deviations generically spoil the standard radiation-matter-dark-energy sequence. Power-law
entanglement corrections can give rise to a moderate early-dark-energy component, but only within a tightly constrained region of parameter space, whereas
quantum-
gravity corrections are suppressed by the Planck scale and remain observationally irrelevant. Consequently, all viable models predict a $\Lambda$CDM-like cosmological background at the present epoch. These findings demonstrate that background cosmology alone imposes stringent constraints on thermodynamically consistent generalized
entropy constructions of this class.
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Quantum Physics
Work Statistics Under Quantum-Jump and Quench Dynamics in Monitored Ising Chains
Manali Malakar and Alessandro Silva
We investigate work statistics in monitored transverse-field Ising chains subjected to both a
quantum quench of the transverse field and either
stochastic quantum jumps or controlled measurement sequences. For generalized measurements, we derive a trajectory-resolved generating function for work statistics in the two-point energy measurement scheme. Evaluating it using a fermionic Gaussian-state formalism, we show that, under
stochastic jump dynamics, the work distribution crosses over from a comb-like structure to an essentially Gaussian form with shrinking sub-Gaussian tails, as the number of detection events grows. For controlled jump protocols, the energy added by each jump is constant when successive jumps are causally disconnected but decreases and then saturates when they lie within each other's light cone, leading to linear growth of average work in the former case and a transient sublinear regime followed by linear growth with a reduced slope in the latter. For monitored quenches, continuous observation washes out the fine structure of the isolated-quench distribution and again drives the statistics toward Gaussian behavior. Together, these results establish work statistics as a trajectory-resolved diagnostic of measurement-induced energy injection and of the emergence or breakdown of additivity in monitored many-body dynamics.
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Optics
Demodulating Digital Holograms with Unknown Uniform Phase-shifts by Spiral Phase Transform
Pavel Trochtchanovitch
The Spiral Phase Transform (SPT) is a generalization of the
Hilbert transform for 2D signals and, as such, can be used for AC signal demodulation. However, phase demodulation with the SPT is complicated by a multiplicative term that depends on the fringe directional map. We derived an analytical formula for the twofold directional map and applied the SPT for the blind reconstruction of phase-shifted digital holograms. Possible phase ambiguities in the unfolded directional map were resolved by satisfying the spatial uniformity condition of the phase shifts. The method was experimentally verified using on-axis and off-axis digital holograms of specularly reflecting subjects.
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Nuclear Theory
High-order perturbative calculations of nuclear ground states: Automated evaluation of many-body diagrams
Zhen Li, Alexander Tichai, Achim Schwenk et al. (+1 more)
We advance the many-body perturbation theory (MBPT) calculations of the ground-state energy and radius of closed-shell
nuclei beyond third order. Using automated diagram generation and evaluation up to fifth order, we present ground-state properties of selected closed-shell
nuclei up to $^{78}$Ni with two- and three-nucleon interactions derived from
chiral effective field theory. A clear convergence trend is observed for the ground-state energy enabling calculations at improved accuracy. We further investigate in detail the decomposition of the fourth-order contributions. For the ground-state energy, the magnitude of the fourth-order contribution is typically less than half of the third order, and a typical cancellation among different classes of diagrams is observed. Finally, we perform a comprehensive comparison between MBPT and non-perturbative in-medium similarity renormalization group (IMSRG) calculations, with the goal to provide insight into many-body uncertainties associated with the IMSRG(2) truncation.
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All authors Zhen Li, Alexander Tichai, Achim Schwenk, Nadezda A. Smirnova
Astrophysics of Galaxies
SchwarMAX: a GPU-friendly Schwarzschild orbit-superposition modelling framework
HanYuan Zhang, David Chemaly, Eugene Vasiliev et al. (+3 more)
The Schwarzschild orbit-superposition method is a highly flexible dynamical modelling tool. It constrains the mass distribution of a
galaxy using line-of-sight velocity and photometric observations. However, constructing such a dynamical model of a
galaxy is computationally expensive. We present SchwarMAX, a new publicly available GPU implementation of the Schwarzschild orbit-superposition method. The GPU-native code is significantly faster than other implementations, with entire model construction taking around a second on GPU A100. Using SchwarMAX, we can explore the distributions of both baryonic and dark matter in a
galaxy across a high-dimensional parameter space. We demonstrate its performance using mock integrated-field spectroscopic unit data generated from an N-body simulated barred
galaxy. We explore the 12-dimensional space of disc, bar and
halo parameters using Markov Chain Monte Carlo. The density profiles and the bar pattern speed of the
galaxy are recovered with good accuracy. We show that the code can be applied to barred
galaxies across a wide range of inclination angles and can be easily extended to other
stellar systems, such as elliptical and
dwarf galaxies.
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All authors HanYuan Zhang, David Chemaly, Eugene Vasiliev, Vasily Belokurov, N. Wyn Evans, Juntai Shen
Cosmology and Nongalactic Astrophysics
The Quiescent Sloshing Core of Abell 496 with XRISM
Angie Veronica, Thomas H. Reiprich, Naomi Ota et al. (+9 more)
Gas motions provide insight into the dynamical history and physical processes within
galaxy clusters. We investigate the kinematics of the ICM in the core of A496, a nearby, X-ray bright, strong cool-core cluster, using high-resolution data from the Resolve micro-calorimeter on board XRISM. We compared our measurement with other Resolve cluster core measurements and further compared our results with simulations and multiwavelength observations. From an optical
redshift analysis, we found that the BCG is at rest with respect to the systemic velocity of the cluster. Despite multiple previously detected cold fronts and harboring a weak central
radio source, Resolve observation shows that the core of A496 is dynamically quiescent. The ICM is moving with respect to the BCG with a LOS bulk velocity of $v_{\rm bulk}=-69_{-20}^{+25}\,\mathrm{km\,s}^{-1}$. We measured a turbulent velocity of $\sigma_{\rm v}=78_{-16}^{+18}\,\mathrm{km\,s}^{-1}$, the lowest value reported by the instrument on a cluster core to date. This value is in good agreement with the velocity dispersion of the H$\alpha$ filament in the core, which may indicate condensation of ICM in the wake of the
radio bubble. Assuming isotropic
turbulence, the ICM turbulent velocity corresponds to a subsonic 3D Mach number of $0.15_{-0.03}^{+0.04}$ and a non-thermal pressure fraction of $1.2_{-0.5}^{+0.6}\,\%$. The mechanical AGN feedback from the recent activity of the central
radio source is estimated to contribute about 7-9% to the ICM heating. The 1D LOS bulk velocity from the SLOW constrained Universe simulation is consistent with the measured value, suggesting that AGN feedback has a negligible contribution. The A496 SLOW turbulent velocity, as in other reported Resolve–simulation comparisons, is higher, but remains within $1.5\sigma$ uncertainty. A496 may represent one of the most quiescent sloshing cores observed so far.
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All authors Angie Veronica, Thomas H. Reiprich, Naomi Ota, Jakob Dietl, Frederick Groth, Klaus Dolag, Efrain Gattuzz, Florian Pacaud, Elke Roediger, Jeremy S. Sanders, Benjamin Seidel, Yuanyuan Zhao
Instrumentation and Detectors
Fast and bright scintillators for ultrafast materials dynamics using 4th generation synchrotron
Zhehui Wang, Dana Dattelbaum, Rachel Huber et al. (+13 more)
We present recent advances in fast and bright scintillators for ultrafast X-ray phase contrast imaging of dynamic materials experiments at the upgraded Advanced
Photon Source (APS-U), a fourth generation synchrotron. APS-U enables hard X-ray imaging at frame rates of at least 13 MHz (corresponding to 77 ns or shorter interframe intervals), creating a new need for scintillators with faster response and higher light output than lutetium yttrium oxyorthosilicate (LYSO). For indirect imaging and diffraction with ultrafast cameras, commercial lanthanum bromide (LaBr3) and cerium bromide (CeBr3) are promising candidates. These materials exhibit decay times approximately a factor of two shorter than LYSO (around 40 ns) and lutetium oxyorthosilicate (LSO), while maintaining comparable light yield per incident X-ray
photon. However, their implementation at APS-U requires addressing several challenges, including material limitations due to hygroscopicity, efficient optical coupling to imaging systems, and high
quantum efficiency for conversion of scintillation light, predominantly at wavelengths below 400 nm, into detectable electronic signals. We report results from material characterization, detector integration and packaging, and beamline experiments of materials with impact. In addition, emerging scintillator classes, including perovskites and high-
entropy materials, are discussed as potential alternatives for next-generation ultrafast X-ray diagnostics.
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All authors Zhehui Wang, Dana Dattelbaum, Rachel Huber, Quanxi Jia, Yuelin Li, Katie Liu, C. L. Morris, Brad D. Price, Robert Reinovsky, Adam Schuman, Nicholas Sinclair, Maria Spiropulu, Yoshimasa Toyoda, Christina Wang, Li-Yuan Zhang, Ren-Yuan Zhu
High Energy Astrophysical Phenomena
JWST Observations of Calcium-Strong Transients: I. Complex Nebular He Emission in SN 2024uj
Saarah Hall, Lindsey A. Kwok, Aravind P. Ravi et al. (+29 more)
We present the first JWST observations of a Calcium-Strong Transient (CaST), SN 2024uj, a rare class of
supernovae (SNe) with observable properties that are consistent with both thermonuclear explosions of white
dwarfs (WDs) and the core collapse of massive
stars. SN 2024uj is offset by $\sim6.6$ kpc from its host and exhibits a double-peaked light curve consistent with shock cooling of nearby circumstellar material. At early times, its optical spectra resemble those of normal SNe Ib, but strong [Ca II] $\lambda\lambda$7291, 7324 emission emerges between $+$2 and $+$17 days after maximum light. Radiative-transfer models of a massive stripped He
star cannot reproduce this early forbidden Ca emission, even with artificially enhanced surface Ca, whereas it arises naturally in thermonuclear scenarios. The $+$150 d JWST/NIRSpec spectrum reveals highly asymmetric, multicomponent He I at both 1.083 and 2.058 $\mu$m. The He extends to $\gtrsim+$5000 km/s, with a strong, narrow peak at $+$1500 km/s, indicating that He is distributed throughout the ejecta with a concentration offset from center. This He distribution overlaps central [Ca II] and [O I], implying a degree of mixing difficult to produce in a massive
star explosion. The He peak might further trace interaction with a shocked, ejected companion in a thermonuclear system. The NIRSpec spectrum also shows molecular CO emission and a rising continuum that, together with a 10 $\mu$m photometric detection, indicates
dust emission extending into the mid-infrared. Given the remote environment, early forbidden Ca, mixed He/Ca/O ejecta, and possible companion signature, we favor a thermonuclear origin for SN 2024uj involving at least one low-mass, partially He-rich WD.
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All authors Saarah Hall, Lindsey A. Kwok, Aravind P. Ravi, Adam A. Miller, Luc Dessart, W. V. Jacobson-Galán, Huei Sears, Moira Andrews, K. Azalee Bostroem, Thomas G. Brink, Joseph Farah, Alexei V. Filippenko, Ryan J. Foley, Griffin Hosseinzadeh, D. Andrew Howell, Saurabh W. Jha, Conor Larison, Chang Liu, Colin W. Macrie, Kate Maguire, Curtis McCully, Nicolas E. Meza-Retamal, Maryam Modjaz, Megan Newsome, Estefania Padilla Gonzalez, David J. Sand, Steve Schulze, Giacomo Terreran, C.-G. Touchard-Paxton, Stefano Valenti, Yi Yang, WeiKang Zheng
Quantum Physics
Optically Active Single Hole Spin in ZnSe
Amirehsan Alizadehherfati, Yuxi Jiang, Kelsey J. Mirrielees et al. (+7 more)
Semiconductor hole
spins offer a pathway to extended coherence times by decoupling from
nuclear magnetic noise, while their
spin-orbit coupling enables fast all-electrical control. In ZnSe, however, realizing this potential has been limited by p-doping challenges. Here, we circumvent this limit by optically activating acceptors within the ZnSe
quantum well. We isolate a single-hole
spin bound to a shallow acceptor, confirmed by antibunching and accessed via the fast (244 ps) radiative recombination of a bound
exciton.
Magnetic and Raman spectroscopy of the ground state reveal an effective hole g-factor of 0.7 and an optical resonance linewidth of 26.7 GHz. Complementary first-principles simulations, together with the experimental results, provide evidence that points toward nitrogen as the most likely acceptor
impurity. These results introduce a promising new platform for optically active
spin qubits and single-
photon sources in ZnSe.
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All authors Amirehsan Alizadehherfati, Yuxi Jiang, Kelsey J. Mirrielees, Nils von den Driesch, Christine Falter, Yurii Kutovyi, Amirehsan Boreiri, Douglas L. Irving, Alexander Pawlis, Edo Waks
Lattice Field Theory
Monte Carlo reconstruction of symmetry-twisted partition function ratios: the critical 3D Ising
José Matos
We introduce a Monte Carlo strategy for directly estimating partition function ratios between distinct global sectors of a
lattice theory. It enlarges the configuration space to sample an interpolating family whose endpoints are the desired sectors, and uses flat histogram methods to reconstruct the corresponding free energy difference. Although the construction is more general, we focus here on the three-dimensional Ising model on the slab $\mathbb{R}^{2}\times S^{1}_{L_{z}}$ at the bulk critical point, comparing the untwisted periodic sector with the $\mathbb{Z}_{2}$-twisted antiperiodic sector. A large-volume and aspect ratio extrapolation gives the
symmetry-twisted thermodynamic Casimir difference $\Delta_{\mathbb{Z}_{2}}=0.327(2)$ directly, without
lattice derivatives or bulk subtractions. This provides an independent twisted sector probe of tensions observed in periodic sector thermodynamic Casimir observables. More generally, the method gives direct but selective numerical access to CFT compactification data, including estimates of the effective thermal screening scale and the $\mathbb{Z}_{2}$-odd sector energy gap on $T^{2}$.
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Astrophysics of Galaxies
AGN radiative feedback as the main regulator of [O III] outflow activity and obscuration in X-ray AGN
Carolina Andonie, Andrea Merloni, Catarina Aydar et al. (+12 more)
Large-scale ionised
outflows and
nuclear obscuration are fundamental manifestations of AGN activity, yet direct observational evidence linking these phenomena remains scarce. We use the eROSITA Final Equatorial Depth Survey, among the largest uniform optical spectroscopic
datasets of X-ray AGN, to investigate how AGN
accretion rate affects ionised
outflow kinematics and X-ray obscuration. Our sample comprises 2.840 AGN at z<0.82 with high-quality SDSS spectra. Through optical spectral fitting, we measure Eddington ratios ($\lambda_{Edd}$) and [O III] emission-line kinematics, tracing ionised
outflows. In addition, we use archival eROSITA X-ray spectroscopy with X-ray stacking analyses to constrain the obscuration of the sample, $N_H$. We find that (1) 35% of the entire sample hosts a [O III]
outflows ($W_{80}>600$ km/s), with the
outflow incidence increasing with the AGN luminosity from 15% at $L_{AGN}<10^{44}$ erg/s up to 60% at $L_{AGN}>10^{46}$ erg/s; (2) the
outflow incidence increases with Eddington ratio from 29% at $\log \lambda_{Edd}<-2.3$ to 50% at $\log \lambda_{Edd}>-1.7$; and (3) the AGN obscuration decreases with Eddington ratio, as sources with $\log\lambda_{Edd}>-1.7$ are 5 times less obscured than lower Eddington ratios AGN. In addition, we find that 1% of the sample populates the "forbidden region" of the $N_H-\lambda_{Edd}$ plane, where the
outflow incidence peaks at 52%, consistent with a short-lived feedback phase. Notably, when matching the Eddington ratios samples in AGN luminosity, these trends vanish, implying that radiation pressure drives changes in
outflow activity and obscuration, while the black hole mass does not play a significant role. Our results are in agreement with AGN radiative feedback scenarios, where the Eddington ratio regulates the AGN environment by driving powerful,
galaxy-wide
outflows and shaping the amount of circumnuclear material.
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All authors Carolina Andonie, Andrea Merloni, Catarina Aydar, Benny Trakhtenbrot, Johannes Buchner, Brivael Laloux, Mara Salvato, Peter Boorman, David M. Alexander, Marcella Brusa, Pietro Baldini, Tiago Costa, Victoria A. Fawcett, Zsofi Igo, Kirpal Nandra
Mesoscale and Nanoscale Physics
An analog ac voltage amplifier based on a single straintronic magnetic tunnel junction
Cael Johnson, Rahnuma Rahman and Supriyo Bandyopadhyay
Magnetic tunnel junctions (MTJs) are known for their digital applications (
memory and logic). A special class of them called "straintronic"
magnetic tunnel junctions (s-MTJ) has lately emerged as a potential platform for analog applications because their conductance can be varied continuously with mechanical strain generated with a gate voltage. The conductance versus gate voltage (transfer) characteristic always has a linear region and that can be leveraged for a variety of analog applications. Here, we discuss one such application, namely analog voltage amplification. If the s-MTJ's gate voltage is fixed around the midpoint of the linear region and a small ac voltage is superimposed on it, then the ac voltage can be amplified without distortion as long as its amplitude is small enough to avoid gate voltage excursion beyond the linear region. Unlike a transistor-based voltage amplifier whose amplification is determined solely by the transistor's internal parameters - namely the transconductance and Early resistance - here the amplification can be varied by an external power supply voltage. We examine the maximum allowed amplitude and frequency of input signal for distortion-free amplification by modeling the magnetization dynamics and derive an expression for the amplification.
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Chemical Physics
A differential derivation of the Obara-Saika relation for Gaussian electron repulsion integrals
Charles C. Forgy and David A. Mazziotti
The Obara-Saika (OS) method is one of the most widely used techniques in
quantum chemistry for evaluating electron repulsion integrals (ERIs) via a set of recurrence relations that build higher angular momentum integrals from lower-order ones. The original derivation by Obara and Saika proceeded by directly relating integrals of differing angular momentum. In this work, we present a compact novel derivation of the OS vertical recurrence relation based solely on differential relations between Gaussian basis functions, expanding on a method suggested in earlier work. By explicitly deriving the required derivative expressions we identify all non-zero primitive terms contributing to the full ERI to develop a hierarchical formulation of the OS recursion relations. This approach has pedagogical value as a rigorous and self-contained derivation. Additionally, the resulting organization exposes independent primitive derivative quantities and may be useful for code generation and parallel implementations on modern GPU architectures.
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Quantum Physics
Velocity of a Quantum Particle in a Classically Forbidden Region
Christian Beck, Sheldon Goldstein, Dustin Lazarovici et al. (+2 more)
Recently, Sharoglazova et al. [Nature 643, 67 (2025)] proposed a procedure for determining the speed of a
quantum particle in the classically forbidden region of a potential step, and implemented it in a beautiful experiment. The inferred speeds disagree significantly with the Bohmian velocities, which the authors presented as an experimental challenge to Bohmian mechanics. This is puzzling because the speeds are inferred from particle populations in coupled waveguides for which Bohmian mechanics and standard
quantum mechanics make identical predictions. We resolve the puzzle by a detailed theoretical analysis of the experimental setup. We show that the speed inference rests on an assumption that fails in the relevant (evanescent) regime according to both Bohmian mechanics and standard
quantum mechanics – namely that the inter-waveguide tunneling time is set by the transverse coupling and is not affected by
entanglement with the longitudinal degree of freedom. We also consider a second speed estimate suggested by Sharoglazova et al., which is based on the Büttiker dwell time formula for particles in the forbidden region. We show that the authors applied the formula incorrectly, and that a correct application yields exact agreement with the predictions of Bohmian mechanics. Our analysis includes explicit calculations of Bohmian trajectories, dwell times, and longitudinal speeds in the two-dimensional waveguide model of the experiment.
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All authors Christian Beck, Sheldon Goldstein, Dustin Lazarovici, Roderich Tumulka, Nino Zanghi
Astrophysics of Galaxies
The Stellar "Snake"-V: the census within 3 kpc in the Solar Neighborhood
Xiang-Ming Yang, Ju-Yong Zhang and Hai-Jun Tian
We present a
Gaia DR3 source-level catalogue of
Stellar Snake complexes within 3 kpc of the Sun. We define a
Stellar Snake as a mutually coherent association of
stellar overdensities, characterised by consistent positions, kinematics, orbital invariants, and ages, rather than a single gravitationally bound object. Moving beyond catalogue searches seeded by known open clusters, our framework operates directly on
Gaia sources to recover extended, low-density substructures and interconnecting
stellar bridges. The multi-stage pipeline extracts statistically significant, non-overlapping base nodes, infers homogeneous parameters using a PointNet point-cloud regressor, and links these nodes into large-scale macro-structures in a nine-coordinate feature space spanning positions, velocities, age log t, and derived dynamical quantities (E, L_Z). After FoF-
topology checking and boundary resolution, the final catalogue contains 1,180
Stellar Snake candidates with 4,196 base nodes and 692,408 unique member-
star entries. Derived parameters are compared with external open-cluster catalogues and spectroscopic
benchmarks. We introduce a graph-relation Snake Reliability Index (SRI) with Gold/Silver/Bronze grades to quantify structural coherence. A spatial-kinematic partition diagnostic identifies candidate subdivisions and provides core scores. At the population level, the catalogue shows an age–
metallicity pattern in the jointly inferred parameters, a declining upper envelope of observed member-
star entries toward older inferred ages, and a projected association between young Snake nodes, nearby spiral-arm loci, and the Radcliffe Wave. This homogeneous inventory provides an observational foundation for probing the formation, coherence, and dynamical
evolution of hierarchical
stellar complexes in the Milky Way.
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High Energy Physics (Theory)
Escape from Ostrogradsky via Hidden Ghost Parity
Sam Bateman and Neil Turok
We present a counterexample to Ostrogradsky's famous "no go"
theorem as usually interpreted in
quantum field theory (QFT), namely a four-derivative, UV-complete QFT with a consistent perturbative expansion which describes high energy scattering processes. We carefully quantize the theory on an $\textit{indefinite}$ space of states - a Krein space - using covariant methods which ensure perturbative causality and unitarity (in the form of the optical
theorem) to all orders. We generalize the Born rule to Krein spaces and prove that all tree level transition probabilities are positive in spite of the presence of ghosts. A key role in the proof is played by a hidden "ghost parity"
symmetry which becomes explicit when the theory is embedded in a two-derivative, two-field $O(1,1)$-symmetric perturbative field theory.
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Astrophysics of Galaxies
Search for Quasar Pairs with ${\it Gaia}$ Astrometric Data. III. Discovery of 9 dual and projected quasars
Qihang Chen, Zizhao He, Zhuojun Deng et al. (+3 more)
We report the low-resolution long-slit spectroscopic observations and confirmations of 11
quasar pair candidates, which are selected from the MGQPC catalog presented in the first paper of our series work (hereafter, Paper-I) and the early version of this catalog. The spectroscopic follow-up was carried out with 5 spectrographs equipped on 3
telescopes, and the major discoveries include 6 dual
quasars and 3 projected
quasars. One of the dual
quasars has a high
redshift of $\sim$ 3.1. The LQ hypothesis of 3 dual
quasars cannot be completely ruled out. We investigated the reason why previous spectroscopic surveys missed several new
quasars. We discussed a projected
quasar with a wide-separation
lensing configuration, as well as two
quasar-
star projections that mimic the configuration of lensed
quasars. The photometric
redshifts for the 11 observed candidates were extracted from the second paper of our series work (hereafter, Paper-II) to illustrate their positive role in mitigating contamination from projected
quasars and
quasar-
star projections. We also reviewed and discussed the confirmation strategies for dual and lensed
quasar candidates, and outlined future confirmation strategies for them in the context of the era dominated by large-scale spectroscopic and imaging surveys.
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All authors Qihang Chen, Zizhao He, Zhuojun Deng, Liang Jing, Xingyu Zhu, Jianghua Wu
Earth and Planetary Astrophysics
Planet formation in chemically diverse and evolving discs II. Chemical fingerprints in planetary atmospheres
E. Pacetti, D. Turrini, E. Schisano et al. (+13 more)
Giant planets form in protoplanetary discs, where the coupled dynamical and chemical
evolution of gas and solids determines the composition of the material they accrete. We investigate how
planet formation and migration shape the
primordial elemental makeup of
giant-
planet atmospheres. Our aim is to link atmospheric compositions to
planets' formation pathways and the time-dependent chemical properties of their natal discs. We couple 1D models of viscously evolving discs - incorporating radial
dust drift and volatile chemistry - with N-body simulations of planetesimals interacting with a growing and migrating
giant planet. Four chemical scenarios and three representative grain sizes (0.1, 20, and 100 micron) are explored. We track the
accretion of carbon, oxygen, nitrogen, and sulphur to derive atmospheric elemental ratios normalised to
stellar values (* denotes
stellar normalisation). We identify three atmospheric classes corresponding to distinct
accretion regimes: gas-dominated, characterised by N/O* > C/O* > C/N* and unconstrained or substellar S/N* (near-
stellar C/S*); planetesimal-dominated, showing N/O* < C/O* < C/N*, S/N* >= C/N*, and C/S* <= C/O*; and drift-enhanced, exhibiting N/O* < C/O* < C/N* and markedly superstellar volatile-to-refractory ratios. N/O*, C/N*, and S/N* vary systematically with migration extent, although degeneracies arise for
planets forming beyond the CO and N2 snowlines; C/O* remains largely insensitive.
Metallicity alone does not uniquely trace the solid-to-gas
accretion balance in drift-dominated regimes. Variations in the disc's chemical state and
dust size imprint distinctive volatile-ratio patterns across these classes, providing complementary constraints on disc properties. This multi-element framework establishes predictive trends to guide the interpretation of atmospheric spectra from facilities like JWST and Ariel.
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All authors E. Pacetti, D. Turrini, E. Schisano, S. Molinari, C. Walsh, C. P. Dullemond, S. Fonte, R. S. Klessen, U. Lebreuilly, P. Hennebelle, S. L. Ivanovski, R. Politi, D. Polychroni, P. Simonetti, L. Testi, V. Cottini
High Energy Physics (Phenomenology)
Putting Jet Substructure on Track(s)
Kyle Lee, Ian Moult and Wouter J. Waalewijn
One of the main advances in analysis strategies at the Large
Hadron Collider (LHC) has been the ability to study the detailed structure of energy flow within high transverse momentum jets, a field referred to as jet substructure. Jet substructure has provided new ways to search for new physics, measure Standard Model parameters, and study the dynamics of the strong
nuclear force. To push to the next level of precision, and to make measurements of increasingly subtle correlations, requires exquisite angular resolution achieved through the use of tracking information. In this paper we leverage recent progress in our understanding of factorization
theorems and renormalization group techniques to present the first complete calculations of jet substructure observables at the LHC on tracks. We compute projected energy correlators up to four points at next-to-leading collinear logarithmic accuracy, matching the state of the art for jet substructure observables, but extending to tracks. This marks a significant step in enhancing the
collider physics program, enabling precise and systematically improvable comparisons between experimental measurements and theoretical calculations, made possible by the exceptional angular resolution of tracking.
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Strongly Correlated Electrons
Single-worldline theory for a dissipative Mott transition
Oscar Bouverot-Dupuis, Alberto Rosso and Laura Foini
In one dimension at zero temperature, local baths with spectral exponent $s$ can stabilize a compressible, non-superfluid dissipative phase between the Mott
insulator and Luttinger
liquid. The dissipative-to-Mott transition is accessible neither to perturbative renormalization-group methods nor to the free-
fermion description of the conventional Mott transition. Here, we show it is governed by the worldline of a single doped excitation, whose geometrical roughness determines the critical exponents. Without dissipation, this worldline undergoes Brownian motion, recovering $\beta=\nu=1/z=1/2$. Dissipation turns it into a long-range interacting interface, yielding continuously varying exponents $\beta=\nu=1/z=s-1$ for $1<s<3/2$, and $\beta=\nu=1/z=0$ for $s<1$. The same theory identifies $s=3/2$ as the threshold above which the dissipative phase disappears. Large-scale Monte Carlo simulations of both the single-worldline theory and the original many-body model quantitatively support these predictions.
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