Instrumentation and Methods for Astrophysics
Open Science in Astrophysics: Citation Benefits of Open Code, Open Data, and Open Access
Parth Joshi and Rupert Croft
We analyze the relationship between open-accessibility in data, code, and paper text in astrophysics using a sample of 53,194 peer reviewed papers published between January 2021 and April 2025, drawn from NASA's Astrophysics Data System (ADS). We measure eleven quantities: open accessibility of text, open-code status, open-data status, number of grants received, code size, programming
language, data repository size, citation count, number of authors, paper length, and publication date. We break down citation advantages based on six astrophysical sub-fields:
Solar System,
Planet,
Stellar, ISM, High Energy, and
Galaxies+Cosmology, determined by keywords. This is accomplished by tuning a multivariate least-squares regression model with alongside partial correlations and non-parametric tests to isolate the contribution of each facet of openness. After controlling for the aforementioned quantities, we find significant citation advantages associated with all three forms of openness: open data (+32%, p < 10^-24), open access (+26%, p < 10^-67), and open code (+16%, p = 0.003). The open-data citation advantage is present in all six sub-fields, and especially in
Galaxies+Cosmology and ISM, which have the strongest cultures of sharing simulation outputs and observational data products. Open-code and open-data sharing rates are highest in
Galaxies+Cosmology and HEA (~0.9% and ~2.9%), reflecting their more developed community data infrastructure, and lowest in
Solar System and ISM, where data is distributed on platforms not taken into account by this study. Our findings support the long held notion that public access comes with concrete personal incentives for authors in terms of citations.
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Solar and Stellar Astrophysics
SPHEREx 0.75 to 5 $\mu$m Spectra for a Sequence of Nearby Brown Dwarfs
Zafar Rustamkulov, J. Kirkpatrick, Rachel Akeson et al. (+21 more)
The SPHEREx all-sky survey has now measured the R$\sim$40-100 infrared spectra of thousands of nearby brown
dwarfs in the chemically rich 0.75-5 $\mu$m range. The survey's wide spectral coverage and high S/N permits flux measurements that capture several broadband molecular absorption features, and upwards of 80$\%$ of the total bolometric luminosity of most brown
dwarfs. Atmospheric models are known to yield systematic disagreements in the inferred temperatures and radii of brown
dwarfs, necessitating benchmarking against observations. In this work, we present SPHEREx spectra across a broad sequence of 37 nearby field brown
dwarfs, ranging from L0 to Y4 ($\sim$2500-250 K) and compare them to theoretical expectations. We additionally compile spectra for separate low-
gravity and low-
metallicity objects, and show how they trend with constant spectral type. We fit the measured spectra to the well-known forward model grids Sonora Diamondback, Elf Owl, BT-Settl, ATMO2020 and ATMO2020++ and compare their goodness-of-fit as a function of wavelength, spectral type, and treatment of clouds and chemistry. We find that the models continue to struggle to simultaneously fit the J/H/K peaks and the 4 $\mu$m opacity window, especially in L/T transition objects. The largest deviations appear around the chemistry-sensitive CO$_2$ and CO features. Despite these offsets, the models broadly capture their trends across the L/T transition, with the observed sample of field
dwarfs strongly preferring the weak vertical mixing ($k_\mathrm{zz}$ = 10$^4$ cm$^2$s$^{-1}$) Elf Owl models over strong mixing. The spectra shown here along with future SPHEREx data will help guide improvements to models.
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All authors Zafar Rustamkulov, J. Kirkpatrick, Rachel Akeson, Michael W Werner, Matthew Ashby, Tzu-Ching Chang, Shuang-Shuang Chen, Asantha Cooray, Brendan Crill, Olivier Dore, C. Dowell, Andreas Faisst, Howard Hui, Woong-Seob Jeong, Miju Kang, Phil Korngut, Carey Lisse, Daniel Masters, Gary Melnick, Chi Nguyen, Roberta Paladini, Volker Tolls, Yujin Yang, Michael Zemcov
Materials Science
A general-purpose atomic cluster expansion interatomic potential for niobium
Aleksei Egorov, Ralf Drautz and Thomas Hammerschmidt
Niobium, a body-centered cubic transition metal, poses a challenge for interatomic potentials, which struggle to capture its properties, such as
phonons, high-pressure behavior, energy barriers to dislocation glide, and others. To tackle this challenge, we constructed a general-purpose atomic cluster expansion (ACE) potential for niobium. We trained our ACE on thousands of density functional theory (DFT) structures spanning a diversity of local environments. We validated it across a range of properties and compared it with existing empirical and machine learning (ML) potentials, including a novel universal ML potential. The resulting ACE balances accuracy, efficiency, and robustness, enabling large-scale exploration of niobium with near-DFT precision. Finally, our ACE held its own in a stringent test: a near-million-atom molecular dynamics simulation of fracture
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General Relativity and Quantum Cosmology
Reference Frames and Gravitational-Wave Polarizations: Symmetry Classification and Preferred-Frame Phenomenology
Jie Zhu and Hao Li
Gravitational wave (GW) polarizations are traditionally classified in a fixed frame ($E(2)$ classification), which does not account for how polarization patterns change under Lorentz boosts. In this work, we derive the explicit transformation laws for all six GW polarizations under longitudinal and transverse boosts. For
gravity theories devoid of preferred frames, we propose a
symmetry-based classification of the GW polarizations they admit. Among our key findings, we demonstrate that a propagating mode with five degrees of freedom strictly locks its longitudinal and breathing scalar amplitudes via the universal relation $A_l/A_b = -2(1-k^2/\omega^2)$. For theories with a preferred frame, we analyze Bumblebee
gravity and reveal that preferred-frame effects induce significant GW birefringence and observer-dependent polarization mixing. Crucially, we identify a novel vector-to-tensor polarization conversion mechanism, where vector modes in the preferred frame inevitably generate observable tensor polarizations for moving detectors, offering a new pathway to test Lorentz-violating
gravity. Our framework provides a novel, observer-independent classification of GW polarizations and reveals previously unnoticed polarization mixing effects.
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Strongly Correlated Electrons
Strongly frustrated 2D magnetism in a 3D hexagonal perovskite
Bocheng Yu, Otkur Omar, Songtai Lv et al. (+12 more)
Exotic
quantum phenomena are often found to occur in
spin systems that exhibit low-dimensional magnetism. By combining
nuclear magnetic resonance,
neutron scattering, and
muon-
spin spectroscopy ($\mu$SR) techniques, we report a rare instance of strongly frustrated two-dimensional (2D) magnetism in a three-dimensional (3D) hexagonal perovskite. Here, Ba$_2$La$_2$MnTe$_2$O$_{12}$, a triangular-
lattice magnet, is shown to undergo a
magnetic transition at $T_\mathrm{N} \approx$ 4.4 K, below which the manganese moments form a 120$^{\circ}$ AFM order within the $ab$-plane, while staying disordered along the $c$-axis. This exotic ground state, which exhibits ideal 2D magnetism, is highly consistent with the persistently strong
spin fluctuations and the large internal field distributions revealed by zero-field $\mu$SR. Further, the 2D magnetism also leads to a significant frustration, much larger than that of most known magnetically-ordered frustrated systems. Our work on Ba$_2$La$_2$MnTe$_2$O$_{12}$ not only challenges the interpretations of
magnetic order in other 3D hexagonal perovskites, but it also provides insight into how the dimensionality affects the exotic
magnetic states.
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All authors Bocheng Yu, Otkur Omar, Songtai Lv, Long Ma, Zhengcai Xia, Jing Meng, Yanran Yang, Jie Ma, Yang Xu, Qingfeng Zhan, Vladimir Yu. Pomjakushin, Haiyuan Zou, Shang Gao, Toni Shiroka, Tian Shang
High Energy Physics (Phenomenology)
Finite modular Coleman-Weinberg inflation
Yoshihiko Abe, Komei Goto, Tetsutaro Higaki et al. (+2 more)
We propose a modular symmetric inflationary model based on a Coleman–Weinberg potential generated by integrating out heavy vector-like
quarks that couple to the complex modulus field $\tau$ through modular forms. In this framework, the imaginary part of modulus $\tau$ plays the role of the inflaton, while the real part is identified with a heavy
axion. We show that the model successfully explains the current cosmological observations. We further discuss reheating through modulus-dependent gauge kinetic functions and the cosmology of the
axion. The
axion oscillation dominates over the Universe after the reheating via inflaton decay, and then it decays before Big Bang Nucleosynthesis in the viable parameter region. The
quantum fluctuation of the
axion can be of order $\mathcal{O}(1)\% $ of that of the inflaton, which would induce isocurvature perturbations that may be detectable in future observations.
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All authors Yoshihiko Abe, Komei Goto, Tetsutaro Higaki, Junichiro Kawamura, Tatsuo Kobayashi
Materials Science
Effect of granules anisotropy on "double quantum" magnetic resonance excitation in nanogranular composites
A.B. Drovosekov, M.Yu. Dmitrieva, A.V. Sitnikov et al. (+2 more)
Films of metal-
insulator nanogranular composites (CoFeB)x(Al2O3)100-x with different contents of the metal
ferromagnetic (FM) phase CoFeB (x ~ 15-50 at.%) are investigated by the method of electron
spin resonance (ESR) in a wide range of frequencies (f = 7-80 GHz) and temperatures (T = 4.2-300 K). Besides the conventional FM resonance signal, the experimental spectra demonstrate an additional absorption peak with a double effective g-factor g ~ 4 which is explained within the
quantum mechanical "
giant spin" model by excitation of "double
quantum" transitions in FM granules CoFeB. According to the theory, the intensity of this "double
quantum" peak is a complex function of frequency and temperature, including as parameters the granule
magnetic moment and anisotropy. Experimentally, the size and anisotropy of the granules can be varied either changing the nominal FM phase content x in the composites or annealing the samples at different temperatures. Here we study the effects of concentration x and thermal annealing of (CoFeB)x(Al2O3)100-x films on their ESR spectral parameters. The observed behavior of the "double
quantum" peak intensity is well explained within the considered "
giant spin" theoretical concept. In conclusion, we demonstrate the correlation between the size of FM granules in nanocomposites and their anisotropy, indicating the surface origin of this anisotropy.
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All authors A.B. Drovosekov, M.Yu. Dmitrieva, A.V. Sitnikov, S.N. Nikolaev, V.V. Rylkov
Mesoscale and Nanoscale Physics
Real-time dynamics of triplet-resonant tunneling driven by nonequilibrium phonons
Kazuyuki Kuroyama, Sasha R. Valentin, Arne Ludwig et al. (+4 more)
Driven nonequilibrium systems can host emergent functionalities beyond
equilibrium, but real-time access to excited-state dynamics remains limited. Here we report real-time measurements of
phonon-driven charge and
spin dynamics in excited states of a double
quantum dot. Under
phonon irradiation, resonant inter-dot tunneling emerges at triplet resonance. Time-resolved charge sensing reveals that the resonant inter-dot tunneling is strongly modified by
spin blockade. For weaker inter-dot coupling, the nonequilibrium
phonon environment generates a unidirectional transport cycle along the
phonon density gradient.
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All authors Kazuyuki Kuroyama, Sasha R. Valentin, Arne Ludwig, Andreas D. Wieck, Yasuhiro Tokura, Seigo Tarucha, Sadashige Matsuo
Atomic Physics
Surface charges in a Rydberg atom-nanowaveguide hybrid quantum system
Aswathy Raj, Anna Kortel, Krishna Jadeja et al. (+4 more)
Hybrid
quantum platforms based on highly excited Rydberg atoms coupled to nanophotonics devices offer a promising route toward scalable
quantum networks and integrated
quantum technologies. However, the close proximity of Rydberg atoms to dielectric nanostructures makes these systems particularly susceptible to uncontrolled surface electric fields that can lead to a degradation of the excitation process. Here, we experimentally investigate Rydberg excitation of
laser-cooled $^{87}$Rb atoms via the evanescent field of an optical nanofiber in the presence of fiber-guided red- and blue-detuned light fields as used to trap ground state atoms in fiber-based dipole traps. We observe a time
evolution of the Rydberg excitation spectrum when both the dipole trapping fields are on and the additional spectral features that appear can be suppressed by applying an external oscillating electric field to the system, strongly indicating that surface charge accumulation is responsible for the observed spectral feature. The experimental results are reproduced qualitatively by a model that incorporates DC energy level shifts arising from electric fields generated by charges deposited on the nanofiber surface. We identify Rydberg-ground state collisional ionization, which is enhanced by the dipole trapping fields, as the dominant mechanism for charge generation. These results provide new insight into charge dynamics at dielectric nanophotonic interfaces and establish practical guidelines for mitigating surface charge-induced electric fields in fiber-integrated Rydberg
quantum systems.
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All authors Aswathy Raj, Anna Kortel, Krishna Jadeja, Dylan J. Brown, Alexey Vylegzhanin, Robert Löw, Síle Nic Chormaic
Quantum Physics
Quantum Memory Advantage from Contextuality
Shiroman Prakash
Quantum contextuality is a vital non-classical resource, yet illuminating the precise mechanisms through which it enables unconditional computational advantages remains a challenge. We translate graph-theoretic formulations of contextuality into an unconditional
quantum memory advantage for formal
language recognition. We define a promise problem on an exclusivity graph $G$ where any classical finite automaton respecting exclusivity requires $N \ge \chi(G)$
memory states, whereas a QFA requires a
memory of dimension $d = \xi(G)$. The gap between these bounds isolates a structural, information-theoretic incompatibility between classical and
quantum descriptions that we term representational contextuality. For Boolean orthogonality graphs, this exacts an exponential classical
memory penalty ($d=\mathcal{O}(n)$ vs $N=2^{\Omega(n)}$). Finally, we demonstrate a sharp algorithmic phase transition: allowing the classical machine a finite confusability of mutually exclusive events reduces this exponential classical
memory cost to $\mathcal{O}(n)$.
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Materials Science
Atom-selective spin-polarized transport in a charge-ordered altermagnet
Liu Yang, Yuan-Yuan Jiang, Xiao-Yan Guo et al. (+6 more)
Altermagnets provide a promising platform for
spin-polarized transport without net magnetization, but their transport properties are usually discussed in terms of momentum-space
spin splitting. Here, using first-principles calculations and
quantum transport simulations, we show that the charge-ordered altermagnet $\alpha$-Fe$_2$PO$_5$ exhibits a distinct form of real-space
spin selectivity despite weak altermagnetic
spin splitting near the
Fermi level. The charge order creates inequivalent Fe$^{2+}$ and Fe$^{3+}$ sites within each sublattice, while the puckered C-type
antiferromagnetic stacking suppresses inter-sublattice transport. As a result, electron and hole doping activate
spin-polarized transport predominantly through Fe$^{3+}$- and Fe$^{2+}$-based channels, respectively. These atom-selective channels carry opposite
spin polarizations on the two
antiferromagnetic sublattices, giving rise to a globally compensated charge current with hidden Néel
spin character. We further propose an all-in-one $\alpha$-Fe$_2$PO$_5$ tunnel junction, where matching or mismatching atom-selective conduction channels yields orders-of-magnitude conductance modulation. Our findings establish a real-space design principle for atomically controlled
spin functionality and spintronic devices.
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All authors Liu Yang, Yuan-Yuan Jiang, Xiao-Yan Guo, Yi-Dong Liu, Xian-Zhe Chen, Wen-Jian Lu, Yu-Ping Sun, Ming Li, Ding-Fu Shao
High Energy Astrophysical Phenomena
FRB20250613A: a remarkable repeating FRB with apparent millisecond-timescale scattering variations
T. Dial, A. T. Deller, Alexa C. Gordon et al. (+8 more)
FRB20250613A is a repeating FRB discovered by the Australian SKA Pathfinder and localised to a low-
metallicity dwarf galaxy at a
redshift of $z = 0.0987 \pm 0.0001$. FRB 20250613A exhibits a plethora of exotic features that likely overlay the imprint of the circum-burst environment on some intrinsic features of the source. Here we perform a comprehensive analysis of bursts detected by ASKAP, MeerKAT, and the Murriyang Parkes
radio telescopes. Bursts during the MeerKAT epoch show a large apparent variance in scattering on timescales of minutes to hours. Polarimetric analysis of the full sample shows spectral depolarisation with variability on timescales of days and changes in rotation measure of $\sim$ 300 rad m$^{-2}$ over days to months. This suggests a highly turbulent magneto-ionised environment. We find significant preference for separations of $\sim$6.8$\pm$0.8 ms in multi-component bursts that we suggest is likely intrinsic to the burst emission mechanism. Finally, we find that a subset of bursts exhibit variations in these propagation effects on burst components separated by just milliseconds, that are difficult to explain by changing sightlines, but plausibly due to non-linear
plasma effects in the circum-burst environment caused by the high field strength of the FRB emission. These properties, which demand a nearby turbulent screen of material, are all consistent with the FRB progenitor being embedded in the dense
stellar wind of a Be
star binary companion, objects which are relatively plentiful in low-mass and low-
metallicity galaxies like the FRB20250613A host.
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All authors T. Dial, A. T. Deller, Alexa C. Gordon, P. A. Uttarkar, R. M. Shannon, Ziteng Wang, M. Caleb, Wen-fai Fong, Marcin Glowacki, Kelly Gourdji, Joscha N. Jahns-Schindler
High Energy Physics (Phenomenology)
Leading-twist to higher-twist generalized parton distributions of the pseudoscalar mesons at non-zero skewness
Abi Jebarson A, Navpreet Kaur and Harleen Dahiya
We investigate the multidimensional partonic structure of
spin-0
mesons, specifically the pion and the kaon, by evaluating their complete set of eight generalized parton distributions (GPDs) up to twist-4. Utilizing the light-front
quark model (LFQM) with the Brodsky-Huang-Lepage (BHL) prescription, we compute these distributions in the kinematically rich non-zero skewness ($\xi \neq 0$) domain, strictly within the DGLAP region, $x \in [\xi, 1]$. To construct a three-dimensional tomographic picture, we perform
Fourier transforms of the momentum-space GPDs to obtain the impact parameter dependent parton distribution functions (IPDPDFs) in the transverse plane and the corresponding diffraction patterns in the longitudinal coordinate space. The numerical results explicitly reveal the consequences of $\mathrm{SU}(3)$
flavor symmetry breaking in the LFQM, as the strange
quark in the kaon dynamically shifts spatial localizations compared to the lighter up
quarks. We also observe that while higher-twist correlations exhibit massive amplitude scaling in the pion, they are heavily suppressed by the larger macroscopic mass of the kaon.
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Medical Physics
Closed-loop coupling of personalised and foundation models for real-time treatment guidance with MRI
James Grover, Emily A. Hewson, Andrew Phair et al. (+5 more)
Image-guided therapies, including radiotherapy, biopsy and deep
brain stimulation, rely on real-time targeting of anatomical structures. However, in the presence of motion, imaging latencies create a temporal misalignment between observed and true anatomy, compromising treatment accuracy. Artificial intelligence-based frameworks have increasingly been presented to close this latency gap, but leading personalised models can fail due to a lack of stable anatomical grounding. Foundation models can provide grounded behaviour, but they do not adapt to real-time, individual patient dynamics. Here we introduce a closed-loop coupling framework that synergises patient-specific temporal prediction with continuous
segmentation-based anatomical interpretation from a foundation model. A personalised model predicts future anatomy to compensate for system latency, while a streaming foundation model provides anatomical supervision used to continuously update the temporal predictor in real time during treatment. We validate the framework using a digital phantom and intrafraction
magnetic resonance imaging (MRI) from patients undergoing MRI-guided radiotherapy. For a prediction horizon of 400 ms, the proposed method improves anatomical prediction and reduces dosimetric error compared with existing approaches, within clinically relevant latency constraints. These results establish closed-loop coupling as a general strategy for real-time image-guided intervention.
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All authors James Grover, Emily A. Hewson, Andrew Phair, Michael Ferraro, Hilary L. Byrne, Paul Keall, Michael G. Jameson, David E.J. Waddington
Astrophysics of Galaxies
Dissecting the 3D chemo-dynamical structures of NGC~1381: A galaxy hosting an ancient slow bar with an accretion-related bulge and thick disc
Yunpeng Jin, Ling Zhu, Shude Mao et al. (+4 more)
We applied the barred population-orbit superposition method developed in our 2025 papers to construct 3D chemo-dynamical models for the barred S0
galaxy NGC~1381 in the Fornax cluster. Based on the
stellar orbits in the models, we decomposed NGC~1381 into six components: (1) a dynamically warm
nuclear disc with $f_{\rm nucl}\sim5\%$; (2) a rigidly rotating, BP/X-shaped bar with $f_{\rm bar}\sim30\%$; (3) a dynamically hot, spheroidal bulge with $f_{\rm bulge}\sim17\%$; (4) a dynamically cold thin disc with $f_{\rm thin}\sim28\%$; (5) a vertically extended thick disc with $f_{\rm thick}\sim16\%$; and (6) a dynamically hot, spatially diffuse
stellar halo with $f_{\rm halo}\sim5\%$. The
nuclear disc, bar, and thin disc are metal-rich ($[Z/\rm H]\gtrsim0$), $\alpha$-poor ($\rm[Mg/Fe]\lesssim0.2$), and old ($\sim13\rm\,Gyr$), corresponding to in situ formation in the early Universe. The bulge, thick disc, and
stellar halo are metal-poor ($[Z/\rm H]\lesssim0$), $\alpha$-rich ($\rm[Mg/Fe]\gtrsim0.2$), and younger than or comparable in age to the in situ components, suggesting ex situ formation via minor mergers. Further analysis of
stellar population gradients reveals that the thick disc and
stellar halo, with their flat
metallicity and [Mg/Fe] gradients, are likely dominated by a similar ex situ population. In contrast, the bulge exhibits a negative
metallicity gradient ($\nabla[Z/\rm H]_{bulge}<0$), which might originate from either predominantly ex situ
stars or a mixture of in situ and ex situ
stars; its ex situ fraction cannot be quantified with the current data. Our modelling also reveals a slow bar ($\mathcal{R}=2.40_{-0.27}^{+0.54}$), with a bar pattern speed of $\rm\Omega_p=34_{-7}^{+4}\,km\,s^{-1}\,kpc^{-1}$, a bar length of $R_{\rm bar}=2.24_{-0.22}^{+0.43}\rm\,kpc$, and a corotation radius of $R_{\rm CR}=5.38_{-0.28}^{+1.59}\rm\,kpc$, consistent with its ancient formation time.
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All authors Yunpeng Jin, Ling Zhu, Shude Mao, Marie Martig, Francesca Pinna, Glenn van de Ven, Yuchen Ding
Lattice Field Theory
Gradient Flow Renormalization Schemes for Composite Fermion Operators
Matthew Black, Anna Hasenfratz and Oliver Witzel
We introduce gradient flow (GF) normalization prescriptions for fermionic composite operators in which the flowed
fermion wavefunction renormalization factor is fixed nonperturbatively using either the partially conserved axial charge or the conserved vector current. The resulting $A$ and $V$ schemes are defined through standard flowed two-point correlation functions and therefore avoid the backward-flow construction required by local ringed-scheme definitions. In the short-flow-time limit, the $A$ and $V$ schemes can be matched to $\overline{\mathrm{MS}}$ using known ringed-scheme short-flow-time expansion (SFTX) coefficients. We show how these schemes can be implemented through ratios of two-point correlation functions, leading to simple nonperturbative determinations of renormalization factors, anomalous dimensions, and
evolution factors which connect
lattice-accessible flow times to shorter flow times where perturbative matching is reliable. We illustrate the method with RBC-UKQCD domain-wall
fermion ensembles, including a GF determination of the ratio of matching factors $Z_V/Z_A$, and a new GF determination of the renormalized strange
quark mass.
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Quantum Physics
A Versatile Analytical Model for Fast and Accurate Determination of Feedline-Coupled Resonators for Superconducting Qubit Readout
Zhen Luo, Lea Richard, Ivan Tsitsilin et al. (+4 more)
Superconducting
quantum chips commonly utilize quarter-wavelength ({\lambda}/4) transmission line resonators as readout
circuits. An analytical model for the accurate determination of resonance frequencies and coupling Q-factors of feedline-coupled superconducting resonators is introduced. The model leverages four-port microwave network analysis, integrating boundary conditions and conformal mapping techniques to compute even- and odd-mode impedances in edge-coupled coplanar waveguide (CPW) structures. Its versatility allows application to both planar and 3-D heterogeneous architectures, making it a powerful tool for resonator design. To validate the model, a test chip with {\lambda}/4 resonators of varying geometries is fabricated and measured in a cryogenic environment. Comparisons with finite element method (FEM) simulations and experimental measurements confirm the model's accuracy, with resonance frequencies and coupling Q-factors aligning closely across configurations. This proposed model facilitates the design of superconducting resonators in readout
circuits for more effective, scalable, and adaptable
quantum computing architectures.
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All authors Zhen Luo, Lea Richard, Ivan Tsitsilin, Christian M.F. Schneider, Marco Dietz, Stefan Filipp, Amelie Hagelauer
Computational Physics · Cross-listed from math.NA
A Nonstandard Finite Difference Scheme for a Nonlinear Parabolic Equation with p-Laplacian-Type Diffusion
Achraf Zinihi, Matthias Ehrhardt and Moulay Rchid Sidi Ammi
We propose and analyze a nonstandard finite difference (NSFD) scheme for nonlinear
parabolic equations involving a p-
Laplacian-type
diffusion operator in one- and two-dimensional spatial domains. Following Mickens' design principles, the proposed discretization employs a nonlinear denominator function phi(.) together with a nonlocal approximation of the nonlinear
diffusion term Delta_p, yielding a structure-preserving discrete model. The scheme is designed to retain key qualitative properties of the continuous problem, including positivity, boundedness, and stability, which may be lost by standard finite difference methods (FDMs). We establish the well-posedness of the continuous model, derive the NSFD scheme, and investigate its consistency, convergence, and local truncation error. Numerical experiments confirm the theoretical results and demonstrate that, unlike the standard explicit FDM, the proposed NSFD scheme avoids spurious oscillations and nonphysical negative solutions even for relatively large time-step sizes.
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High Energy Physics (Experiment)
GPU-accelerated spectrum reweighting for new-physics searches in solar neutrino–electron scattering
Guangbao Sun, Xuefeng Ding, Liang Sun et al. (+1 more)
Precision measurements of
neutrino–electron elastic scattering provide low-energy tests of weak interactions and beyond-the-Standard-Model effects. Non-standard interactions (NSIs) and an anomalous
neutrino magnetic moment modify the differential cross section through different kinematic terms, but both can alter the normalization and shape of the
recoil-electron spectrum. Likelihood tests are computationally costly when each parameter point requires the
recoil spectrum to be propagated through a detector response obtained from Monte Carlo (MC) simulation. We present a GPU-accelerated spectrum-reweighting framework that avoids regenerating detector MC samples for each new-physics parameter point. Bin-to-bin weights are applied at the
recoil-spectrum level and folded with a fixed two-dimensional response model in
recoil and reconstructed energy. This keeps the detector response inside the likelihood calculation while reducing each parameter update to operations on precomputed spectra and response kernels. The implementation uses NVIDIA Thrust transformation–reduction primitives and is compiled from a common source for CUDA and OpenMP back ends. In the
benchmarks considered here, one likelihood evaluation takes ${\sim}87$ ms on an NVIDIA RTX 3080Ti and ${\sim}52$ ms on an NVIDIA A30X; the latter gives a $58\times$ speedup over a single CPU thread and ${\sim}2.5\times$ over a fully loaded 64-thread CPU. The consumer-GPU result demonstrates that interactive parameter scans are feasible on a single workstation. The main acceleration, however, comes from avoiding detector-MC regeneration at each parameter point rather than from GPU execution alone. The framework applies to
neutrino–electron scattering analyses in which the new-physics dependence can be represented by reweighting an existing
recoil spectrum, including
flavor NSI and
magnetic-moment cases studied here.
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All authors Guangbao Sun, Xuefeng Ding, Liang Sun, Xiang Zhou
Nuclear Theory
Astrophysical S-factor Calculation for p-p Fusion Reaction
Arushi Sharma, Ishwar Kant and O.S.K.S. Sastri
The current S-factor calculations for weak pp interaction involve the determination of low-energy penetration probability using the bare Coulomb Gamow factor, which renders the nature and shape of actual interaction to be insignificant. In this work, the astrophysical S-factor is obtained utilizing the WKB action integral evaluated over the inverse scattering potential for the S-wave of pp-interaction, which does not involve bare Coulomb interaction in it. The np and pp inverse potentials are constructed using the phase function method by providing a reference potential consisting of three smoothly combined Morse functions, whose model parameters are optimized using a genetic
algorithm to minimize the mean-squared error between the obtained and expected scattering phase shifts. The overlap integral between the bound-state deuteron and the scattering state of pp S-wave has been evaluated at different energies all the way up to 0.0001 MeV, and corresponding fusion cross-sections are determined. The WKB action integral has been computed at all energies without any approximations. Finally, the S-factor at various energies are calculated, and S(0) has been obtained using a supervised neural network. The value of S(0) obtained using our methodology involving complete evaluation of WKB action integral without approximations is $(0.1261\pm 0.0043)\times10^{-25}$, which is almost one order of magnitude lower than the currently accepted values using various methods. The inverse potentials constructed using the reference potential approach, which does not involve explicit consideration of
nuclear $\&$ Coulomb interaction, resulting in a finite range of pp-interaction, have been successful in providing a new estimate for the astrophysical s-factor that depends on the nature and shape of the actual potentials.
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Biological Physics
When is vaccine prioritization worth optimizing?
Mi Feng, Zhaohua Lin, Changsong Zhou et al. (+1 more)
Optimizing vaccine prioritization is often treated as the default policy response when vaccine supply is limited. Yet optimized prioritization carries administrative, ethical and communication costs, motivating an upstream question: whether differences among vaccine allocations can alter epidemic outcomes enough to make optimization epidemiologically necessary. We show that optimization is not always worth pursuing: in some regimes, vaccination markedly reduces epidemic burden, but many feasible allocation rules perform almost equally well, making the necessity of optimization low. We quantify this necessity as the range of epidemic outcomes generated by different allocations under fixed supply and show that it is governed by competition between vaccinating high-contact groups to slow transmission and vaccinating groups that benefit most directly: necessity is low when these protection routes are balanced and high when one dominates. Increasing transmission intensity changes this balance and drives a transition in the optimal allocation from transmission-focused prioritization toward direct protection. Different prevention objectives exhibit distinct transition thresholds, creating regimes in which optimizing one objective substantially compromises another, thereby revealing when the choice of prevention target matters most. This framework reframes vaccine prioritization as a prior decision problem, identifying when optimization is warranted, when simpler rules suffice, and when prevention goals conflict.
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All authors Mi Feng, Zhaohua Lin, Changsong Zhou, Liang Tian
Mathematical Physics · Cross-listed from math.DS
Periodic orbits with prescribed negative energy for relativistic Keplerian problems
Alberto Boscaggin, Guglielmo Feltrin and Duccio Papini
Using a variational approach, we study the existence of periodic solutions with prescribed energy for the relativistic equation \begin{equation*} \dfrac{\mathrm{d}}{\mathrm{d}t}\left(\dfrac{m\dot x}{\sqrt{1-|\dot{x}|^{2}/c^{2}}}\right) = -\alpha \frac{x}{|x|^{3}} + \nabla W(x), \qquad x\in\mathbb{R}^{N}\setminus\{0\}, \end{equation*} where $W$ is a lower-order perturbation of the Kepler potential. The main difficulty stems from the fact that the Kepler singularity is critical for the associated Maupertuis functional, lying exactly at the boundary between the weak force and strong force regimes. To overcome the resulting lack of compactness, we use a penalization procedure and develop a suitable min-max scheme combined with a blow-up analysis of near-collision critical sequences. As a consequence, we establish the existence of periodic solutions on prescribed negative energy levels, obtaining non-perturbative results in every dimension $N\geq 2$.
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Strongly Correlated Electrons
Weak Ferromagnetism in NiS$_2$ under Nanocrystallization
Hayato Miyazaki, Tomohiko Yoshinaga, Ojiro Miyazaki et al. (+7 more)
Structurally well-ordered NiS$_2$ nanocrystals with an average diameter of $27.0 \pm 6.5$ nm retain the bulk-like two-step
antiferromagnetic transitions, as shown by magnetization and heat-capacity measurements. Below the lower transition, the nanocrystals exhibit a hysteretic
ferromagnetic response with large coercivity, exchange bias, and a vertical loop shift after field cooling, whereas the $M$-$H$ response just above the transition is nearly linear. These features are best explained by uncompensated surface moments generated where the low-temperature
antiferromagnetic order terminates at the nanocrystal surface. The absence of a clear additional bulk-like weak-
ferromagnetic component constrains homogeneous-canting models and indirectly favors a domain-wall scenario for the weak ferromagnetism of bulk NiS$_2$.
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All authors Hayato Miyazaki, Tomohiko Yoshinaga, Ojiro Miyazaki, Akira Matsuo, Koichi Kindo, Hirofumi Ishii, Tatsuya Kawae, Tetsuya Kida, Masashi Nantoh, Yoichi Ishiwata
Quantum Physics
Dependency-Aware Circuit Scheduling for Multi-Core Quantum Systems to Minimize Makespan
Rajeswari Suance P S, Ruchika Gupta, Maurizio Palesi et al. (+1 more)
Multi-core
quantum computing architectures have emerged as a promising solution to the
qubit scalability limitations of monolithic NISQ devices.
Quantum algorithms are expressed as
quantum circuits composed of single- and two-
qubit gates. However,
circuit scheduling in multi-core
quantum systems remains largely unexplored. Reducing overall execution time (makespan), increasing core utilization, and hiding communication latency behind computation depends on effective scheduling. In this paper, we first introduce a layered scheduling approach as a baseline where
quantum gates within the same layer are executed in parallel, while layers themselves are executed sequentially. We then propose a greedy scheduling strategy which schedules each gate as soon as all its dependencies and required resources are available. This allows fine-grained parallelism across cores. Our evaluation shows that on real
benchmarks, greedy scheduling achieves an average 40% reduction in makespan and improvement in core utilization. The results suggest that the use of intelligent
circuit scheduling to exploit parallelism can greatly enhance the speed of
circuit execution in multi-core
quantum architectures.
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All authors Rajeswari Suance P S, Ruchika Gupta, Maurizio Palesi, John Jose
Optics
Finite-Size Effect Induced Spatial-Spectral Mode Splitting in Membrane Metasurfaces
Chih-Zong Deng, Mu-Hsin Chen, Chun-Hao Chiang et al. (+4 more)
This work reports the spatial-spectral engineering and finite-size quantization of optical modes within a triangular-
lattice silicon nitride membrane metasurface. Truncating the
lattice into a finite square cavity breaks translational
symmetry and lifts modal degeneracy, splitting optical modes into discrete cavity-envelope sub-modes. High-resolution photoluminescence (PL) scanning reveals distinct spatial field distributions. The corner-localized sub-mode features the highest Q-factor due to multipolar far-field destructive interference, whereas the core-localized sub-mode exhibits strong radiative coupling. PL mapping reveals a symmetric, four-fold clover-like wavelength arrangement. These results demonstrate that boundary-induced deterministic
symmetry can override underlying
lattice characteristics, offering a robust strategy for precise spatial-spectral tailoring of light-matter interactions at the nanoscale.
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All authors Chih-Zong Deng, Mu-Hsin Chen, Chun-Hao Chiang, Jui-Han Fu, Vincent Tung, Masanobu Iwanaga, Ya-Lun Ho
Statistical Mechanics
Single-cell-level distributions and relationships can differentiate cell-division and growth models
Vikas, Rahul Marathe and Anjan Roy
Complex interactions among regulatory molecules determine the rules underlying
cell growth and division in microbial
cells. While the governing molecular network may not always be obvious, it is well known that correlations among certain physiological quantities measured in experiments, such as birth-size, division-size, division-time, and division-added-size, can differentiate among various
cell-division models, such as Timer, Sizer, and Adder. Here we show that, apart from these correlations, which we extend for the case of
stochastic single-
cell growth and
stochastic asymmetric partitioning, probability distributions of these quantities and statistical relationships between them can also be used to differentiate between these division models. Interestingly, we show that these quantities can not only differentiate the division models, but also distinguish among the single-
cell growth paradigms, such as linear and exponential growth. We then demonstrate this differentiability among various division and growth models by comparing our analytical results with published experimental data. We further show that these results remain valid even when the growth rate of a
cell is correlated with the growth rate of
cells from previous generations in the lineage.
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Quantum Physics
Bridging quantum mechanics and nonlinear optics in Raman scattering
Naoki Fukutake and Hideaki Kano
We present a theoretical framework for spontaneous Raman scattering that fundamentally bridges
quantum-mechanical and nonlinear-optical approaches. By conceptualizing spontaneous Raman scattering as a stimulated Raman gain or loss event seeded by the
quantum vacuum field, we rigorously derive the spontaneous Raman cross-section directly from the third-order nonlinear susceptibility. Crucially, this framework predicts the existence of a hitherto unrecognized phenomenon: "spontaneous Raman loss" (sRL), which acts as the
vacuum-seeded counterpart to stimulated Raman loss, complementing traditional spontaneous Raman scattering (spontaneous Raman gain, sRG). Furthermore, we establish a rigorous connection to the traditional Kramers-Heisenberg-Dirac (KHD) theory, revealing that the spontaneous process is governed by interference before a detector between the signal field emitted from molecules and the
vacuum field itself that stimulates the molecules. This insight uncovers a direct correspondence between the sRG susceptibility and the rotating/counter-rotating interference terms in the KHD formula. Ultimately, we extend the foundational KHD theory by incorporating previously unrecognized essential terms, achieving perfect analytical agreement between the
quantum mechanical and nonlinear optical descriptions of Raman scattering.
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Quantum Physics
Closed-loop control for two-qubit gates with trapped ions
Eduardo J. Páez, Seyed Shakib Vedaie and Barry C. Sanders
State-of-the-art two-
qubit gates with trapped ions employ open-loop control that rely on simplified models to precompute control sequences. Our aim is to introduce closed-loop control for two-
qubit gates to correct disturbances as they occur during the gate implementation. We introduce a spectator ion into the ion chain used for
quantum logic processing, where it couples with the other ions through collective motional modes. The spectator ion's position is continuously monitored by driving dipole transitions and detecting the resultant fluorescence. We show that incorporating a spectator ion is feasible for linear Paul trap implementations and is expected to reduce the two-
qubit gate Bell-state preparation infidelity by an order of magnitude with the deleterious effects of position monitoring being negligible compared to the thermal effects that exist in the system, even in the absence of the spectator ions. Mathematically, we describe driven ion-trap dynamics, including the spectator ion, by a
stochastic quantum master equation involving the amplitude-modulation multimode-motional coupling gate, motional drift, thermal effects,
recoil from
photon scattering, spontaneous decay, and light shift. Our on-the-fly control method employs reinforcement learning with the reward function based on the actual
geometric phase of the spectator ion. A key advantage of our approach is that we introduce a control method that involves `learning' and correcting disturbances happening in the trap on-the-fly, thus achieving high-fidelity gates. Our approach will lead to a significantly higher two-
qubit gate fidelity at a reduced calibration overhead owing to the small parameter drift in the control system.
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Computational Physics · Cross-listed from cs.CE
A Multi-Resolution Finite-Volume Inspired Deep Learning Framework for Spatiotemporal Dynamics Prediction
Xin-Yang Liu, Xiantao Fan and Jian-Xun Wang
Predicting complex spatiotemporal dynamics in physical processes often demands computationally expensive numerical methods or data-driven neural networks that suffer from high training costs, error accumulation, and limited generalizability to unseen parameters. An effective approach to address these challenges is leveraging physics priors in training neural networks, known as physics-informed deep learning (PiDL). In this work, we introduce the Multi-Resolution Finite-Volume-inspired network, MuRFiV, designed to capitalize on the conservative property of finite volume on the global scale and the expressive power of deep learning on the local scale. We demonstrate the effectiveness of MuRFiV on several spatio-temporal systems governed by partial differential equations (PDEs), including Burgers' equation, shallow water equations, and incompressible Navier-Stokes equations. By
embedding PDE information into the deep learning architecture, MuRFiV achieves strong long-term prediction accuracy and remains stable over very long autoregressive rollouts, significantly outperforming data-driven neural network baselines. This result highlights the promise of combining multiresolution learning with finite-volume-inspired inductive bias for accurate and robust long-term prediction of complex dynamics.
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Solar and Stellar Astrophysics
Optimization Algorithm for Determining the Source Surface Radius Based on Parker Solar Probe in situ Measurements from Encounters 1 to 19
Shiouhe Wang, Fang Shen, Yi Yang et al. (+2 more)
The Potential Field Source Surface (PFSS) extrapolation is a method for estimating the large scale coronal
magnetic field from photospheric magnetograms. The source surface serves as the outer boundary of its solution domain, and is typically a spherical surface. An appropriate source surface radius ($R_{ss}$) enables more accurate identification of the coronal
magnetic field
topology and estimation of the open flux, thereby potentially enhancing the accuracy of space weather modeling. We prove the well-posedness of the PFSS forward problem and establish the existence and uniqueness of the optimal source surface by combining compactness of the admissible set with continuity of the objective functional. The objective functional is the mean squared error (MSE) between PFSS extrapolation and Parker
Solar Probe (PSP) radial
magnetic field measurements after Parker spiral backmapping and radial scaling for Encounters 1-19. The optimization
algorithm is validated with an analytical solution, and Advanced Composition Explorer (ACE) in situ measurements are used as an independent cross-validation
dataset. Additional evaluation metrics and Pareto analysis are used to identify the dominant metrics between open flux and polarity prediction accuracy. Our results show that the optimal $R_{ss}$ derived from the
algorithm generally increase from
solar minimum into the ascending phase of
solar cycle 25. The optimized solution improves open flux agreement while preserving or improving polarity prediction accuracy relative to $2.5R_{s}$. The Pareto frontiers show a transition for dominant metrics from open flux during
solar minimum to polarity prediction accuracy during the ascending phase.
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All authors Shiouhe Wang, Fang Shen, Yi Yang, Xueshang Feng, Jiansen He