Optics
Enhanced Third-Harmonic Generation in a Bound State in the Continuum Assisted Multiband All-Dielectric Metasurface
Partha Mondal, Hadeel Alamoudi, Rodrigo P. Sanchez et al. (+4 more)
Multiband Fano resonances are demonstrated in the near-infrared (near-IR) using an all-dielectric metasurface whose unit
cell consists of four silicon nanoblocks on a glass substrate. An in-plane asymmetry triggers
symmetry-protected quasi-bound states in the continuum (QBICs), producing multiple high-Q resonances. Their origin is identified through multipolar decomposition of the scattering cross section and field distributions at the resonances. The strong field localization at these resonances enables efficient multiband third-harmonic (TH) generation in the ultraviolet (UV), with a maximum simulated conversion efficiency of $8.5 \times 10^{-3}$ at a peak pump intensity of $1.6\,\mathrm{GW/cm^{2}}$. The metasurface is fabricated in symmetric and asymmetric configurations, and its linear and nonlinear responses are measured under normal incidence. A TH conversion efficiency of $1.2 \times 10^{-6}$ is obtained at a peak pump intensity of $3.25\,\mathrm{GW/cm^{2}}$. These results establish a route to multiband photonic devices, including multiwavelength
lasers, multiband harmonic generation, and single-
photon sources for
quantum photonics.
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All authors Partha Mondal, Hadeel Alamoudi, Rodrigo P. Sanchez, Redha H. Al Ibrahim, Boon S. Ooi, Iman Roqan, Hakan Bagci
Quantum Physics
Designing robust molecular spins for quantum technologies with theoretical chemistry
Timothy J. Krogmeier, Pranay Venkatesh, Mikayla Z. Fahrenbruch et al. (+3 more)
Molecular
spins represent a versatile platform for
quantum information science, with the potential to offer chemically tunable, addressable
qubits. However, achieving this requires understanding and mitigating
quantum decoherence. This Chapter provides a theoretical overview of current state-of-the-art chemical theory connecting ab initio electronic structure with open
quantum system dynamics to guide the rational design of long-lived molecular
qubits. Beginning at the electronic level, multi-reference and relativistic electronic structure methods to parameterize effective
spin Hamiltonians are discussed, with a primary focus on accurately capturing $g$-tensors, zero-field splitting, and hyperfine interactions. These parameters feed into models of
spin-
phonon and
spin-
spin coupling to quantify $T_1$ and $T_2$ relaxation across various environmental regimes. This Chapter evaluates a hierarchy of dynamical methods, ranging from factorization to
matrix product state approaches, balancing computational cost against accuracy and generalizability. Ultimately, mapping these theoretical models to molecular architecture can establish design principles, such as isotopic substitution and spatial
spin delocalization, to understand and extend coherence lifetimes.
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All authors Timothy J. Krogmeier, Pranay Venkatesh, Mikayla Z. Fahrenbruch, Anthony W. Schlimgen, Andres Montoya-Castillo, Kade Head-Marsden
Optics
Nonlinear wave dynamics in photonic time crystals
Fabio Biancalana
Maxwell's wave equation in the presence of a cubic nonlinearity and a periodically time-varying refractive index (a photonic time
crystal) is reduced, for spatially monochromatic waves, to a nonlinear Mathieu equation. Near the principal momentum gap this equation admits an autonomous two-dimensional reduction whose complete
Hamiltonian phase portrait can be obtained analytically. We derive the two homoclinic separatrices corresponding to temporally localised momentum gap
solitons, identify the nonlinear centres and the critical
Hamiltonian value $H_c$, and calculate the point of maximum linear parametric gain. We then consider spatially localised pulses and show how the nucleation of multiple spatiotemporal gap
solitons can produce a broad supercontinuum in momentum space; for stronger seeds, transient extreme nonlinear localisation can accompany an abrupt additional broadening of this momentum spectrum. These results establish a direct connection between Floquet amplification, nonlinear saturation, homoclinic dynamics, and momentum space spectral broadening in nonlinear photonic time
crystals.
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Physics Education
Development of the RIOT 2 for use in LA-supported classrooms
Gina M. Quan, Cassandra Paul, Nithin Keshavamurthy et al. (+3 more)
This paper describes the development of the RIOT 2, an observational tool that can be used to study classrooms in which there are multiple members of an instructional team. The RIOT 2 is based on the Real-time Instructor Observational Tool (RIOT), which characterizes the behavior of an instructor over time. While the RIOT was previously developed for classrooms with only one instructor, our team has developed a version to observe classrooms supported by Learning Assistants (LAs). LA are undergraduate peer educators who facilitate discussions in active-learning classrooms. Unlike the RIOT, the RIOT 2 allows for the categorization of LA-instructor interactions. In this paper, we describe the development of RIOT 2 and present some initial data collected using the RIOT 2. While our data are preliminary, they illustrate how the RIOT 2 may be useful for future research and practice. This work is part of a broader research effort to understand how LA-faculty partnerships impact what LAs and instructors do in the classroom.
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All authors Gina M. Quan, Cassandra Paul, Nithin Keshavamurthy, Owen Knight, Aarav Ghai, Kamalbabu Rupanagudi
Instrumentation and Methods for Astrophysics
Performance Analysis of the Asgard/NOTT Nulling Interferometer: Optimizing Observing Modes for High-contrast Detection
J. P. Scott, S. Ertel, T. A. Stuber et al. (+21 more)
We evaluate the performance of three beam-combination schemes, single-Bracewell, asymmetric dual-Bracewell, and symmetric dual-Bracewell, for the forthcoming Asgard/NOTT nulling interferometer at the Very Large
Telescope Interferometer. Utilizing the SCIFYsim end-to-end simulator, we assess the instrument's performance by deriving the precision of calibrated null measurements as a function of
stellar magnitude and simulating observations of varying hot exozodiacal
dust (HEZD) distributions and a hot Jupiter. The study reveals distinct trade-offs for each observing mode. The single-Bracewell mode provides high throughput and preserves spatial information but suffers from poor error suppression. The asymmetric dual-Bracewell mode offers the strongest error suppression for detecting point-like sources, but it inherently suppresses symmetric astrophysical signals such as expected from HEZD. The symmetric dual-Bracewell mode provides a middle ground with modest error suppression while being sensitive to symmetric emission. We conclude that utilizing a combination of all three observing modes provides a robust strategy for detecting HEZD, constraining the structure of its distribution, and identifying false positives from
stellar companions.
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All authors J. P. Scott, S. Ertel, T. A. Stuber, D. Defrère, R. Laugier, J. C. Augereau, P. Chingaipe, G. Garreau, X. Haubois, M. Ireland, F. Kirchschlager, S. Kraus, F. Martinache, M-A. Martinod, K. Missiaen, S. Morel, J. Morren, K. Ollmann, P. Priolet, G. Raskin, M. Salman, N. Schuhler, W. Verstraeten, S. Wolf
High Energy Physics (Phenomenology)
Beyond $\Delta m^2$: Absolute Mass Sensitivity in Neutrino Oscillations
Gustavo F. S. Alves, André L. C. de Gouvêa, Joshua Kaler et al. (+2 more)
Conventional wisdom says that
neutrino oscillations measure only mass-squared differences and not the absolute
neutrino mass scale. This is true, however, only at leading order in the expansion parameters $m_i/E$, the ratios of the
neutrino masses $m_i$ ($i=1,2,3$) to the
neutrino energy $E$. At next-to-leading order, the oscillation phase includes terms proportional to $m_i^4-m_j^4 = \Delta m^2_{ij}(m_i^2+m_j^2)$, and is therefore sensitive to the absolute mass scale. In this paper, we derive the next-to-leading-order corrections using a wave-packet treatment and taking into account the
neutrino-production kinematics. We then apply this result to reactor antineutrinos and find that the JUNO experiment is sensitive to
neutrino masses of a few hundred keV. While not competitive with existing bounds from beta decay, electron capture, and cosmology,
neutrino oscillations provide a novel, complementary probe of the
neutrino mass scale, with sensitivity to a different combination of
neutrino masses.
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All authors Gustavo F. S. Alves, André L. C. de Gouvêa, Joshua Kaler, Shirley Weishi Li, Pedro A. N. Machado
Soft Condensed Matter
Ion-Pairing Enhancement under Osmotic Stress: Disentangling the Effects of Ion and Water Activities
Jay Prakash Singh and Viatcheslav Freger
The dependence of ion pairing on osmotic stress may strongly affect the performance of ionic materials and membranes whose interior is often osmotically stresses, yet quantitative understanding of this dependence and, specifically, the effects of water and ion activities is limited. Motivated by this gap, we analyze the enhancement of ion pairing with osmotic pressure for concentrated aqueous KCl, NaCl, and LiCl solutions using molecular dynamics simulations. Based on rigorous thermodynamic relations, we separate the contributions of ion non-ideality to the pairing constant, varying with osmotic pressure, from other effects including water release and type of ion-pair. Our analysis reveals that ion non-ideality indirectly generates a stronger effect on pairing than the direct one of water release. However, its effect is moderated and may even be reversed for more hydrated pairs by a similarly large and opposite effect of ion-pair non-ideality assigned to varying dielectric properties of the solution and water restructuring upon pairing. The interplay between these contributions, including large and pair type-specific hydration effects on the cost of pairing, explains the observed opposing trends: pairing decreases with osmotic pressure for more hydrated solvent-separated pair types while increasing for contact pairs. The trend becomes more pronounced for more hydrated smaller cations, but was fairly independent of the water model used. The results further suggest that dielectric effects enhanced in ionic materials-and, as a result, larger variations of ion-pair non-ideality, compared with aqueous solutions, should have a more significant impact on pairing than water release.
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Astrophysics of Galaxies
The CMZ Asymmetries: Feeding or Feedback?
John Bally
Three-fourths of the dense gas and
dust in the CMZ is located at positive longitudes and positive radial velocities. The majority of compact 24 micrometer wavelength sources are at negative longitudes. These two asymmetries indicate either a recent asymmetric injection of gas along the bar
dust lanes, or that most of the molecular gas is contained in a small number of massive, gravitationally bound clouds, or a major feedback episode which dissociated an entire sector of the CMZ's dense gas.
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High Energy Physics (Theory)
Aliou Togo, Yang Yu, Kaniba Mady Keita et al. (+2 more)
We investigate
holographic superconductors using modern optimisation techniques inspired by machine learning. The critical temperature is obtained by minimising the variational functional for the
eigenvalue $\lambda^2$ with two complementary trial functions: a simple cosine ansatz $F(z)=\cos(a z)$ and a flexible exponential
polynomial $F(z)=\exp(\sum_{n=2}^{N} a_n z^n)$, both of which automatically satisfy the standard boundary conditions. For the cosine ansatz, we perform a one-parameter minimisation and obtain $\lambda^2(\Delta)$ and $T_c/\sqrt{\rho}$ over a wide range of $\Delta$, including the exact values at $\Delta=1$ and $\Delta=2$ to high accuracy. The exponential
polynomial ansatz, with up to 19 coefficients, is optimised using a multi-start L-BFGS-B
algorithm with warm-starting, yielding even better agreement with known exact results. Our numerical data for $\lambda^2(\Delta)$ and $T_c/\sqrt{\rho}$ match the analytical predictions from the literature, confirming the robustness of the variational approach. This work; therefore, demonstrates that a combination of analytic trial functions and modern numerical optimisation provides a powerful, flexible, and efficient tool for exploring
holographic superconductors, and can be readily extended to include backreaction or other sectors in this field.
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All authors Aliou Togo, Yang Yu, Kaniba Mady Keita, Jian-Pin Wu, Younouss Ham`eye Dicko
Instrumentation and Methods for Astrophysics
MORFEO control strategy
Guido Agapito, Lorenzo Busoni, Cédric Plantet et al. (+7 more)
The ESO Extremely Large
Telescope (ELT) will offer unprecedented sensitivity and resolution in the near-infrared, marking a new era for ground-based astronomy. Among its key imaging instruments is MORFEO coupled with MICADO. MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations), formerly known as MAORY, is the largest astronomical adaptive optics system ever designed. It features 12 wavefront sensors and three deformable mirrors, for a total of over 20,000 subapertures and over 6,000 actuators. MORFEO represents one of the greatest upcoming challenges in the field of astronomical adaptive optics. While the design builds upon the heritage of previous AO systems, several architectural choices are entirely new, driven by the unique scale and requirements of this instrument. One of the main challenges is delivering high and uniform wavefront correction across the MICADO field of view. To meet this goal, the MORFEO control strategy adopts a specific approach: sodium
laser guide
stars are used to sense modes above focus only, since differences in beacon altitude can introduce significant aberrations. Natural guide
stars are instead employed to measure and correct for tip, tilt, plate scale variations, and field-averaged focus. In this work, we present the MORFEO control strategy and provide performance estimates across different observing scenarios.
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All authors Guido Agapito, Lorenzo Busoni, Cédric Plantet, Giulia Carlà, Alfio Puglisi, Jean-Pierre Véran, Marco Falotico, Gabriele Umbriaco, Edoardo Redaelli, Paolo Ciliegi
Quantum Physics
Scalable Test of Genuine Multipartite Entanglement via Partially Randomized Measurements
Jan Wojcik, Pawel Chrabkowski and Wieslaw Laskowski
Certifying genuine multipartite
entanglement in
quantum systems can require a number of measurements that grows exponentially with the system size. Here we introduce a criterion based on correlation-tensor subsector lengths restricted to local measurement planes and show that it can be evaluated using partially randomized measurements without an explicit exponential dependence on the number of
qubits. We derive the corresponding bounds for $k$-separable states and illustrate the criterion using representative families of multipartite entangled states. Finally, we demonstrate the practical applicability of the method on an ion-trap
quantum computer by certifying genuine five-partite
entanglement.
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Soft Condensed Matter
Benchmarking the flow of epithelial cell monolayer with self-aligning deformable active membranes
Marcos Pasa, Carine P. Beatrici, François Graner et al. (+2 more)
Collective
cell migration emerges from the interplay between motility, deformability and mechanical interactions, yet incorporating these ingredients into computationally efficient tissue models remains challenging. Here, we
benchmark self-aligning deformable active membranes in a confined-flow geometry that mimics epithelial monolayer migration around a circular obstacle. In this model,
cells are represented as deformable, adhesive membranes whose self-propulsion direction relaxes towards their velocity. By systematically varying the self-
alignment timescale,
cell-
cell adhesion and inlet forcing, we characterize the resulting flows through collective
alignment, relative density, neighbor rearrangements and spatial velocity fields. The model captures a broad spectrum of tissue behaviors, ranging from disordered,
liquid-like flows to highly aligned, solid-like states. Compared with a related multiparticle model, self-aligning active membranes achieve stronger collective
alignment, exhibit a more systematic density response and access states closer to both limits of the solid-
liquid spectrum. We further show that increasing the target shape index promotes
cell elongation and accelerates tissue flow, directly linking
cell-scale deformability to tissue-scale transport. Finally, we compare simulated velocity profiles with experimental measurements from in vitro migrating MDCK epithelial
cell monolayers and find qualitative agreement across multiple horizontal and vertical transects around the obstacle. These results establish self-aligning deformable active membranes as a versatile framework for connecting
cell mechanics, shape adaptation and self-
alignment to collective tissue migration in confined geometries.
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All authors Marcos Pasa, Carine P. Beatrici, François Graner, Leonardo G. Brunnet, Emanuel F. Teixeira
Astrophysics of Galaxies
Old Disks Die Hard: How Does AGN Feedback Suppress Disk Formation in Milky Way Mass Galaxies?
Patricia Fofie, James S. Bullock, Sarah Wellons et al. (+3 more)
The connection between a
galaxy's visual shape and its
star formation rate is one of the oldest established trends in
galaxy evolution, yet the origin of this trend remains unsettled. We analyze two Milky-Way mass
halos simulated with FIRE-2
galaxy formation physics, each run without AGN and with up to three implementations of AGN feedback. We use them to study how and why AGN
star formation suppression affects morphological
evolution over
cosmic time. Both runs without AGN feedback produce prominent, thin,
star-forming spiral disks at $z=0$. Each of the AGN runs has less late-time
star formation, and ends up with a higher spheroid fraction and a lower thin-disk mass fraction. In two instances, the AGN runs produce quenched lenticular
galaxies with no cool gas at $z=0$. The main reason for these morphological differences is that AGN feedback becomes effective just after the onset of disk formation, at “
spin up," in every run. This time-differentiated impact suppresses the formation of disk
stars, especially thin-disk
stars, preferentially because thin-disk formation occurs late. The spheroidal components are assembled early in all runs, before AGN feedback is effective, and are therefore similar in mass and size across runs.
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All authors Patricia Fofie, James S. Bullock, Sarah Wellons, Jorge Moreno, Francisco J. Mercado, Andrew Wetzel
Instrumentation and Detectors
Optical Characterization Measurements of Commercial Polyvinyltoluene Scintillators for Accurate Geant4 Detector Modeling
Fergus Martin Huggins, Micah S. Johnson and Matthew Quinn Buckner
Accurate Monte Carlo simulation of plastic scintillator detectors requires precise wavelength-dependent optical properties. We present measurements of wavelength-dependent refractive index $n(\lambda)$ and bulk absorption length $L_{\mathrm{abs}}(\lambda)$ for six commercial polyvinyltoluene (PVT)-based scintillators (Saint Gobain BC-400, BC-404, BC-408, BC-418, BC-422, and BC-430) at five wavelengths between 372 and 660 nm. Using a precision refraction apparatus and variable-thickness transmission measurements, we characterize material-specific dispersion that deviates substantially from both the manufacturer specification and literature values for pure PVT. Illustrative Geant4 simulations of a BC-422 detector demonstrate a 7.2% reduction in photocathode energy-deposition threshold events when using our measured $n(\lambda)$ compared to the constant manufacturer value, highlighting the practical importance of accurate optical property data for detector design and calibration. We successfully measure absorption lengths for BC-430 at four wavelengths between 372 and 505 nm (2.2-12.4 mm) and for all materials at 372 nm (2.2-38 mm), while establishing lower bounds exceeding 750 mm for weakly absorbing formulations at longer wavelengths.
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Materials Science
Defect-controlled twin activation in crystallographically equivalent magnesium micropillars
Hexin Wang, Fatim Zahra Mouhib, Chunhua Tian et al. (+6 more)
Tensile twinning plays a central role in accommodating <c>-axis plasticity in Mg. In bulk Mg, it typically shows a relatively deterministic response with a low critical stress, whereas in confined volumes it exhibits broad yield-stress distributions that complicate the prediction of small-scale mechanical behavior. Here, site-specific compression tests are performed on 4 $\mu$m-diameter pillars fabricated in a parent Mg
crystal and an adjacent {10-12} twin. The two regions share the same [11-20] compression axis but experienced different prior deformation histories, allowing the influence of the residual microstructural state to be examined at fixed crystallographic orientation. Among 27 pillars, most parent-region pillars yield near 300 MPa, whereas pillars from the twin region span approximately 30 to 300 MPa. Interrupted tests combined with cross-sectional EBSD link individual load drops to discrete twin formation and further show that a pillar containing a pre-existing twin yields at approximately 80 MPa through the migration of the existing twin boundary. Molecular dynamics simulations of 30 nm-diameter pillars resolve possible atomistic pathways at the nanoscale. The simulations illustrate how contact geometry and pre-existing twin embryos alter event selection, and how an activated twin advances rapidly, while coherent twin boundary migration proceeds through disconnection motion accompanied by crystallographically required atomic shuffles. The results attribute the experimental scatter to the local availability of embryos and mobile interfaces, such that the first plastic event is governed by the twinning pathway accessible from the local microstructural state rather than by a single characteristic critical stress. Deformation history can therefore strongly modify the distribution of first plastic events even when the loading orientation is fixed.
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All authors Hexin Wang, Fatim Zahra Mouhib, Chunhua Tian, Sang-Hyeok Lee, Henry Ovri, Julien Guénolé, Sandra Korte-Kerzel, Talal Al-Samman, Zhuocheng Xie
Atomic Physics
Precision calculations of the hyperfine constants and isotope and isomer shifts in low-lying states of 229Th3+
S.G. Porsev and M.S. Safronova
We present high-precision calculations of the hyperfine constants, isotope shift, and isomer shift in low-lying states of Th3+ relevant to spectroscopy of the 229Th
nuclear isomer. The removal energy and hyperfine constants are calculated using a relativistic coupled-cluster method including single, double, and triple excitations, demonstrating the importance of higher-order correlation effects. The isotope shift of the 5f_5/2 -7s transition is evaluated using both the CI+MBPT and CI+all-order methods, providing an estimate of the theoretical uncertainty. We find that the isotope shift is dominated by the field shift, with the mass shift contributing negligibly. Combining the calculated field-shift coefficient with the measured difference in the
nuclear mean-square charge radii of the ground and isomeric states, we predict the 7s isomer shift to be (Delta E^(m,g))= 0.9(1) GHz. These results provide
benchmark atomic data for Th3+ and support ongoing precision spectroscopy of 229Th and the development of a
nuclear clock.
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Superconductivity
Complete Suppression of Thermomagnetic Instabilities in Nb Superconducting Films by Combined Metallic Layers and Ion Irradiation
D. Carmo, A. M. H. de Andrade, R. Giulian et al. (+3 more)
Thermomagnetic instabilities in superconducting films can trigger flux avalanches that disrupt the critical state and impair the performance of superconducting devices. Here we investigate the stabilization of Nb thin films subjected to a perpendicular
magnetic field by two complementary approaches: the addition of normal-metal overlayers and Ar ion irradiation. Magnetization measurements and magneto-optical imaging show that the metallic layers suppress the onset of avalanches at low applied fields, whereas ion irradiation reduces the high-field portion of the instability region by shifting the upper threshold for avalanche activity to lower fields. When combined in the same sample, these two partial stabilization effects lead to complete suppression of thermomagnetic instabilities. In particular, a Nb film coated with a 1~\(\mu\)m-thick Cu layer after irradiation at a fluence of \(5\times10^{16}\)~ions/cm\(^2\) exhibits smooth magnetization curves and avalanche-free flux penetration. This combined treatment restores stable critical-state behavior and provides a practical route for stabilizing Nb superconducting films in thin-film superconducting technologies.
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All authors D. Carmo, A. M. H. de Andrade, R. Giulian, A. A. M. Oliveira, W. A. Ortiz, F. Colauto
High Energy Astrophysical Phenomena
The second Arcminute Microkelvin Imager - Large Array Gamma-ray burst radio afterglow catalog
L. Rhodes, D. Ibrahim, N. Sqalli et al. (+13 more)
Radio observations of gamma-ray burst afterglows provide insight in to the different emitting regions within the jet, its hydrodynamics and burst environment. In this paper, we present the second iteration of the Arcminute Microkelvin Imager - Large Array (AMI-LA) Gamma-ray burst (GRB)
radio afterglow catalog. The catalog consists of 1035 observations of 210 bursts. Our observations range from 0.04 to 900days post-burst. We detect
radio emission associated with 19 events with flux densities spanning 0.1-40mJy, and present a detailed analysis of six events whose light curves have not been published elsewhere. In our individual afterglow analyses, we find that our
radio counterparts show evidence of reverse shock emission 60% of the time. Two of the detected afterglows show evidence of scintillation which we use to place source size limits at tens of days. Of the whole catalog, 50 events have
redshift measurements which we use to find the
radio afterglow luminosity distribution for our sample. Our luminosity distribution spans five orders of magnitude, a larger range than seen in optical and X-ray bands, indicative of the strong dependence of the
radio counterparts on the GRB's physical parameters.
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All authors L. Rhodes, D. Ibrahim, N. Sqalli, G.E. Anderson, R. Fender, A.J. van der Horst, J.S. Bright, A.K. Hughes, D.R.A. Williams-Baldwin, D.A. Green, D. Haggard, A. Horesh, Y. Perrott, P. Scott, T. Staley, D. Titterington
High Energy Physics (Phenomenology)
Gravitational Waves from Dimension-6 Assisted Peccei - Quinn Phase Transitions
Nico Benincasa and Kristjan Müürsepp
We consider a simple model-independent extension of the minimal KSVZ
axion model, augmenting the Peccei - Quinn effective potential with a dimension-6 operator invariant under the Peccei - Quinn
symmetry. We show that this operator can trigger a first-order phase transition and study its cosmological consequences. We map out the parameter space, consistent with present observational constraints, in which the phase transition produces a gravitational wave signal observable at current and future interferometers, and we investigate the resulting dark matter phenomenology. Finally, we present specific ultraviolet completions that generate the dimension-6 operator, each leading to distinct phenomenological signatures, which motivates our model-independent approach.
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Quantum Physics
Efficient Hamiltonian Truncation: Fast Matrix Construction and Quantum Krylov Diagonalization
Rachel Houtz, Marco Knipfer, Konstantin Matchev et al. (+2 more)
Hamiltonian truncation offers a nonperturbative route to
quantum field theory, yet its accuracy is limited by the rapid expansion of the truncated
Hilbert space, which drives up computational cost. We tackle this bottleneck with a hybrid strategy that pairs classical and
quantum algorithms: 1) we develop an efficient basis-generation scheme built on integer partitions; 2) we speed up the construction of the sparse
Hamiltonian matrix using
symmetry-aware
algorithms; and 3) we explore
quantum Krylov diagonalization as a route to the low-lying spectrum. Benchmarking against the free massive scalar and $\phi^4$ theories in two spacetime dimensions, we achieve substantial gains in the computational efficiency of
Hamiltonian truncation and chart a path toward future
quantum implementations.
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All authors Rachel Houtz, Marco Knipfer, Konstantin Matchev, Alexander Roman, Mia West
Materials Science
Thickness-dependent secondary-electron emission from suspended MoS$_2$ membranes in the helium ion microscope
Cyan Kim, David Lister, Philip Jackle et al. (+1 more)
Secondary-electron (SE) emission in the helium ion microscope (HIM) becomes sensitive to membrane thickness when the sample is thin enough for He-ion transmission and when the SEs emitted from the bottom surface are collected. We correlated the total SE intensity of suspended, nanometer-thick MoS$_2$ flakes on lacey carbon with thickness measured independently by electron energy-loss spectroscopy. The response peaks at 40-55 nm, with an apparent back-to-front SE signal ratio reaching 4.7. The peaked, thickness-dependent component is attributed primarily to SE emission at the bottom surface of the flake, rather than to transmitted ions striking instrument surfaces. Applying SRIM ionization profiles, an asymmetric SE-escape model with a longer escape depth on the exit side reproduces the response. We find an effective exit-side escape depth of approximately 10 nm, five times the assumed 2 nm entrance value, suggesting that deposited energy reaches the exit surface far more efficiently than the entrance surface or that the SRIM model's energy deposition profile is shifted by an effect such as channeling. The correlation provides a rapid thickness screen for suspended membranes and a route to testing low-energy ion-solid interaction models in thin materials.
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All authors Cyan Kim, David Lister, Philip Jackle, Karen L. Kavanagh
Atomic Physics
Strong-field Herman-Kluk propagator method for high-harmonic generation in molecules
Phi-Hung Tran, Hao Quan Truong, R. Esteban Goetz et al. (+1 more)
We extend our recently developed semiclassical strong-field Herman-Kluk (SFHK) propagator method to calculate high-order harmonic generation (HHG) in diatomic molecules driven by few-cycle intense
laser fields. On the example of applications to H2 and N2, we show that our method, based on a combination of the Herman-Kluk propagator and the strong-field approximation, can provide very accurate results for both HHG yield and phase, nearly identical to those from the exact numerical solutions of the time-dependent Schrodinger equation. To compare with experimental measurements, averaging over molecular orientations must be performed. Here we demonstrate a distinct and powerful advantage of the SFHK, as its Monte Carlo sampling for the integration over the
alignment distribution can be efficiently combined with the integration over the initial momentum distributions of electron wave-packet right after the tunnel exit. Therefore, the total number of trajectories used for the
alignment-averaged HHG spectrum does not increase much compared to that for a single fixed
alignment. Similar to atomic targets, the main computational task in the SFHK is to solve the classical
Hamiltonian equations for the active electron in the combined electron-target ion potential and electron-
laser interaction. The motion of the center of each electron wave packet in the continuum, represented by a coherent state, is governed by an independent classical trajectory so that the computation can be parallelized very efficiently.
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All authors Phi-Hung Tran, Hao Quan Truong, R. Esteban Goetz, Anh-Thu Le
Accelerator Physics
Generalized space-charge solver for three-dimensional converging or diverging beams
Ji Qiang
Nonlinear space-charge effects play a critical role in the dynamics of high-intensity, high-brightness beams. While conventional space-charge forces scale inversely with the square of the relativistic Lorentz factor ($\gamma$) as beam energy increases, this suppression may not apply to all components of the electromagnetic force. In this paper, we present a generalized space-charge solver that accounts for contributions from transverse currents in three-dimensional (3D) converging or diverging beams. We demonstrate that these additional forces from transverse currents lack an explicit dependence on $\gamma$, potentially rendering them significant in specific high-energy applications. We provide a semi-analytical solution for a 3D converging or diverging beam with the Gaussian density distribution and identify the regimes in which these transverse current forces become comparable to conventional space-charge forces. Furthermore, we present a numerical solution for the generalized model applicable to arbitrary density distributions. Finally, we evaluate the impact of these forces on strongly converging electron beams within the interaction regions of the FCC-ee and ILC, as well as the second bunch compressor of LCLS-II-HE; our results indicate that these extra forces do not significantly alter the final electron beam quality in these specific cases.
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High Energy Astrophysical Phenomena
High-Energy Neutrinos from Supernova Shock Breakouts in Circumstellar Media: Light Curves, Spectra, and Contribution to the Extragalactic Neutrino Background
Tal Wasserman, Eli Waxman and Kohta Murase
Enhanced mass loss from core-collapse
supernova (SN) progenitors shortly before explosion appears to be common, creating a compact, optically thick circumstellar medium (CSM) at $\sim10^{14}-10^{15}$ cm. We derive an analytic description of the light curves and spectra of high-energy
neutrinos emitted by nonrelativistic SN shock breakouts through such CSM, as a function of shock velocity and CSM parameters, accounting for the
evolution of the hydrodynamic structure and the electromagnetic (EM) spectrum as the shock transitions from being radiation-mediated to collisionless. This
evolution determines the time-dependent
neutrino production efficiency, the maximum
proton/
neutrino energy, and the pair-production optical depth. A significant fraction of the
neutrino energy is typically emitted within a few days of explosion, during breakout and before the EM light curve peak, with $1-100$ TeV
neutrinos carrying $\approx10\%$ of the energy of shock-accelerated
protons. The escape of high-energy
photons ($>1$~GeV) is suppressed by pair-production for compact CSM configurations. If enhanced mass losses are common, and assuming that shock-accelerated
protons carry $\approx10\%$ of the collisionless shock energy, CSM SN breakouts may significantly contribute to the observed high-energy
neutrino background, without overproducing a corresponding high-energy gamma-ray background. SNe producing $>1$
neutrino events in a $1\left(10\right){\rm km^2}$ detector are expected at a rate of $\sim0.05\left(1\right){\rm yr^{-1}}$.
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Mathematical Physics · Cross-listed from math.PR
Asymptotically complete free-energy dissipation: a coarse MLSI holds at any positive temperature
Jonas Köppl and Yannic Steenbeck
Everybody learns in school that an out-of-
equilibrium system coupled to a heat bath at a fixed temperature evolves to thermodynamic
equilibrium as time goes on, and the free energy will only decrease on its way there. At least since Holley's 1971 work, mathematicians know this too, in the modest context of classical Ising Glauber dynamics. But does the free energy also asymptotically decrease to the free energy of an
equilibrium state? A typical school kid would say "yes, of course", but since the free energy is only lower semicontinuous, this question is less straightforward than it initially seems. To the best of our knowledge, apart from the uniqueness regime, where one can make use of classical functional inequalities, this question has not previously been resolved rigorously. We prove the asymptotically complete dissipation of the free energy for the classical Ising Glauber dynamics by introducing a coarse modified log-Sobolev inequality, which holds at every positive temperature, in particular in the phase-coexistence regime.
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Statistical Mechanics
Far-from-equilibrium scaling of non-abelian Goldstone modes
Carl Philipp Zelle, Gustav John, Orla Supple et al. (+2 more)
We identify a broad class of nonthermal phases generated by the interplay of continuous
symmetry breaking and weak nonequilibrium driving. Extending Kardar-Parisi-Zhang (KPZ) physics beyond the single $SO(2)$ chronon associated with periodically broken time translations, we construct nonequilibrium nonlinear sigma models for $SO(2)\times O(N)$
symmetry, describing non-Abelian time
crystals with coexisting temporal and internal order. This
symmetry structure arises naturally in driven
quantum materials, active matter, and optically induced periodic states. For rotating and oscillating phases, we derive the Goldstone theories and show that chronon-$O(N)$ couplings remain finite deep in the ordered regime. One-loop renormalization group analysis reveals a KPZ-like dimensional structure: in $d=1,2$, arbitrarily weak nonequilibrium perturbations destabilize the
equilibrium fixed point and generate strongly coupled nonthermal fixed points, realizing emergent
equilibrium breaking. By contrast, for $d > 2$, weak perturbations are irrelevant and effective
equilibrium is restored. A central result is unconventional weak dynamic scaling in the rotating phase: strongly coupled Goldstone sectors acquire distinct universal dynamical exponents despite belonging to the same order parameter. We characterize this scaling analytically and corroborate it through direct simulations in $1+1$ dimensions. In the oscillating phase, we recover and extend weak-scaling regimes known from drifting
polymers. Finally, compactness and topological defects ultimately destroy long-range order but leave experimentally accessible nonthermal scaling windows. Together, these results extend KPZ universality to non-Abelian
symmetry breaking.
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All authors Carl Philipp Zelle, Gustav John, Orla Supple, Romain Daviet, Sebastian Diehl
Quantum Physics
Open system probes of renormalization group flow
Andrew Keefe, Brenden Bowen, Saptarshi Biswas et al. (+3 more)
Open system probes can provide an efficient means to characterize
quantum many-body systems by employing them as engineered environments. The key idea is to map long-range spatial correlations of the environment onto dynamical correlations in the
evolution of a simple
quantum probe. Using the example of a
qubit coupled to a transverse-field Ising model, we show how the non-Markovian rate or spectral flow can be used to identify stable and unstable fixed points, infer scaling dimensions of relevant fields, and deduce the renormalization group flow induced by deformations around any fixed point.
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All authors Andrew Keefe, Brenden Bowen, Saptarshi Biswas, Albion Lawrence, Nishant Agarwal, Archana Kamal
Statistical Mechanics
Far-from-equilibrium topological phase transition in one dimension
Ze-Min Huang, Gustav John and Sebastian Diehl
We uncover a mechanism for far-from-
equilibrium topological phase transitions, via a one-dimensional compact phase model evolving deterministically from random initial conditions. It rests on
topology and
symmetry rather than on phenomenological postulates: phase compactness permits
vortices, and a homogeneous fixed point suppresses their nucleation, with the fixed point itself implied by phase-shift
symmetry. The competition between
vortex-induced disordering and relaxation toward homogeneity drives a continuous nonequilibrium transition, whose universality class we identify as directed percolation (DP). We demonstrate this by constructing the corresponding effective field theory and numerically confirming DP critical scaling through dynamical-scaling analysis.
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Astrophysics of Galaxies
Abundant Heavy Black Hole Seeds from Moderate Lyman-Werner Radiation
Ryan Hazlett, Eli Visbal, Greg L. Bryan et al. (+1 more)
The existence of high-
redshift quasars may indicate that massive black hole seeds formed via supermassive Population III
stars in atomic-cooling
halos with large gas inflow rates; however, the dependence of this process on
halo assembly rate and radiative background remains poorly constrained. We present a large suite of 65 high-resolution cosmological zoom-in simulations of 15 pristine
halos spanning a wide range of Lyman-Werner radiation backgrounds and
halo assembly histories. We introduce a novel method to estimate the final Population III
stellar mass from radial gas infall profiles at the onset of runaway collapse and validate it against simulations from the literature that explicitly follow protostellar
accretion with sink particles, reproducing protostellar masses to within a factor of $\sim2$. We find a clear transition in gas inflow rates between
halos exposed to $J_{\rm 21} \lesssim 1$ and $J_{\rm 21} \gtrsim 10$, with the latter frequently sustaining inflow rates above the adopted threshold for supermassive
star formation and producing estimated
stellar masses up to $10^{5} \, M_{\odot}$. In contrast, the
halo assembly timescale, $M_{\rm Halo}$/$\dot{M}_{\rm Halo}$, shows no statistically significant correlation with predicted
stellar mass, despite
halo assembly rates spanning $0.01$-$7 \, M_{\rm \odot} \, {\rm yr}^{-1}$. The Lyman-Werner radiation field therefore is a stronger predictor of sustained high
accretion within our parameter space. Finally, a semi-analytic model applied to cosmological volumes shows that
halos exposed to intermediate Lyman-Werner backgrounds ($1 \lesssim J_{\rm 21} < 10$) are orders of magnitude more common than those in the high-$J_{\rm 21}$ tail. If sustained high
accretion extends into this intermediate regime, heavy black hole seeds may form in substantially more common environments than required by classical direct-collapse scenarios.
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All authors Ryan Hazlett, Eli Visbal, Greg L. Bryan, Mihir Kulkarni
High Energy Astrophysical Phenomena
No Evidence for Nearby Circumstellar Material in the Type Ia Supernova 2025rbs
Aravind P. Ravi, Griffin Hosseinzadeh, Stefano Valenti et al. (+28 more)
We present a high-resolution spectral time series of the Type Ia
supernova (SN) 2025rbs discovered in the nearby
galaxy NGC 7331. The Automated
Planet Finder (APF) at Lick Observatory and the MAROON-X/IGRINS-2 at Gemini North were used to obtain echelle spectra between -5 and 15 days with respect to the epoch of maximum light. Several unsaturated NaID absorption components along the line of sight are identified, but there is no evidence of time variance in any of them. We measure the equivalent width of the observed diffuse interstellar band around 5780 A and constrain the extinction along the line of sight to SN 2025rbs as $A_V = 0.64\,\pm\,0.32$ mag, corresponding to a moderate reddening of $E(B-V) = 0.21\,\pm\,0.10$ mag (assuming $R_\mathrm{V}$ = 3.1). The observed Ca II H & K interstellar absorption roughly traces NaID in velocity space, suggesting a common origin. Quantitative comparisons between the column densities of Na and Ca gas in these host clouds ($N_{NaID}$ / $N_{Ca II}$ of order unity) argue against their origin in the
Galactic halo gas and instead support absorption due to the interstellar gas of NGC 7331. Time invariance of all the observed absorption features suggests a lack of nearby circumstellar material ($\lesssim$ 10$^{16}$ cm) around the progenitor system of SN 2025rbs. This supports a progenitor scenario for SN 2025rbs with minimal ambient circumstellar gas, consistent with a double-degenerate CO white
dwarf binary system.
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All authors Aravind P. Ravi, Griffin Hosseinzadeh, Stefano Valenti, Saurabh W. Jha, Jennifer Andrews, David J. Sand, Benjamin J. Fulton, William D. Vacca, Melissa L. Graham, Alexei V. Filippenko, Noah Franz, Jeniveve Pearson, Moira Andrews, K. Azalee Bostroem, Collin Christy, Yize Dong, Sebastian Gomez, Daichi Hiramatsu, Emily Hoang, D. Andrew Howell, Brian Hsu, Daryl Janzen, Lindsey A. Kwok, Michael J. Lundquist, Darshana Mehta, Nicolas Meza-Retamal, Curtis McCully, Manisha Shrestha, Bhagya Subrayan, Lauren Weiss, Weikang Zheng