Accelerator Physics
Transverse coupled-bunch instabilities driven by high-order modes near the coupling resonance
You Sun, Weiwei Li, Tianlong He et al. (+3 more)
Betatron coupling near the difference resonance has been explored and adopted in several fourth-generation storage rings, yet its influence on high-order-mode-driven transverse coupled-bunch instabilities has not been systematically established. Using the Hefei Advanced Light Facility (HALF) as an example, we investigate this effect through theoretical analysis and macroparticle tracking simulations. The theoretical predictions agree well with macroparticle tracking simulations in both the weak- and strong-instability regimes, validating the description over the parameter ranges considered. For the vertical HOMs studied with HALF parameters, suitable betatron coupling effectively suppresses the instability, offering potential benefits for transverse stability control.
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All authors You Sun, Weiwei Li, Tianlong He, Penghui Yang, Xiaoyu Liu, Zhenghe Bai
Astrophysics of Galaxies
Environmental dependence of galaxy properties in the DESI DR1 Bright Galaxy Survey: Star formation, morphology, and AGN activity at z < 0.55
Duho Kim
We examined the environmental dependence of
galaxy properties using a parent sample of about 1.4 million BGS_BRIGHT
galaxies from the Dark Energy Spectroscopic Instrument Data Release 1 Bright
Galaxy Survey at $0.05 < z < 0.55$. Using the extended
halo-based group catalogue, we measured how the specific
star formation rate (sSFR), Sérsic index, and active
galactic nucleus fraction depend on
halo mass over $9\leq\log(M_*/\mathrm{M}_\odot)<12$ and $12.5\leq\log(M_h/\mathrm{M}_\odot)<16$. The parent measurements describe the observed sample, and our main conclusions about the
galaxy population are based on comparisons above the completeness limit derived for quiescent
galaxies. Within the same
stellar mass and
redshift bins, the median sSFR is generally lower in clusters than in the field. At intermediate
stellar masses and $z<0.25$, satellites show a lower median sSFR than centrals at fixed
stellar and
halo mass. The environmental dependence of the
star formation reflects differences between centrals and satellites and the changing satellite fraction. The Sérsic index increases only weakly with
halo mass at fixed
stellar mass and
redshift. Among
galaxies in which all four diagnostic emission lines are detected, we find no strong environmental dependence of Seyfert or low-ionisation
nuclear emission-line region fractions at fixed
stellar mass. They are both marginally higher at most in clusters, with the largest but most uncertain differences at the highest
stellar masses.
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Quantum Physics
Oraqle: An Empirical Analysis of Qubit Readout and Discriminators in Quantum Error Correction
Emmanouil Giortamis, Aleksandra Świerkowska, Sandra Stankovic et al. (+3 more)
Quantum error correction (QEC) is the most promising route toward fault-tolerant
quantum computing and, thus, useful
quantum computers. QEC operates as a continuous measure-decode-correct cycle: ancilla
qubits are read out, a decoder infers errors from the resulting syndromes, and corrections are applied before the next round begins. Within this loop, readout occupies a uniquely critical role, as it is the sole source of ground truth available to the decoder. Yet readout is also the slowest and most error-prone operation in the stack, with characteristics that vary across
qubits and drift over time; This complexity propagates directly to the classical control hardware, and in particular to the FPGA-hosted machine-learning (ML) discriminator that must classify each analog signal into a binary syndrome outcome. Despite this central role, QEC performance has not yet been studied in depth from the perspective of readout characteristics, readout length, and their co-design with an ML discriminator. We introduce Oraqle, an end-to-end benchmarking framework that evaluates
qubit-state readout and its impact on QEC performance across real experimentally extracted
qubit-state-readout
datasets, state-of-the-art ML discriminators, multiple QEC codes, and hardware regimes spanning current to projected devices. Our study reveals three asymmetric findings: The measurement duration can be significantly reduced with nearly no penalty to the logical error rate; The discriminator complexity barely affects the QEC performance, as residual errors are written into device physics rather than the model; and the impact of
qubit-state readout on the logical error rate is conditional on where the hardware sits in the QEC landscape, a window that widens as devices mature.
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All authors Emmanouil Giortamis, Aleksandra Świerkowska, Sandra Stankovic, Felix Gust, Benjamin Lienhard, Pramod Bhatotia
Astrophysics of Galaxies
Investigation of Calcium Dust in the Interstellar Medium
Ya-Yu Chu, Sascha Zeegers, Hsien Shang et al. (+7 more)
Calcium is a highly depleted element in the interstellar medium (ISM), however its composition in the solid phase remains elusive. The detection of Ca-bearing
dust has been limited due to its lack of distinct spectral features in the cold phase of the diffuse ISM. X-rays provide a direct method for exploring the absorption and scattering properties of interstellar
dust. In this study, we utilize high-resolution X-ray absorption spectroscopy to characterize Ca-bearing
dust analogs at the Ca K-edge using X-ray Absorption Fine Structure (XAFS). We present new X-ray absorption spectra of seven calcium-bearing interstellar
dust analogs measured at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan. The extinction cross sections, calculated from the laboratory measurements are incorporated in the
dust absorption model AMOL of the X-ray spectral fitting tool SPEX. We select three Low Mass X-ray Binaries (LMXBs) with high column densities, GX 340+00, GX 5-1, and GX 13+1, as background sources to study the intervening ISM along their sightlines. The best-fit models are compared with Chandra archive data using SPEX. Additionally, we employ simulations with the XRISM and NewAthena
telescopes to achieve enhanced resolution and more effective coverage at the energy range near the Ca K-edge. These simulations set the boundary conditions for the future X-ray observation of calcium in the interstellar medium.
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All authors Ya-Yu Chu, Sascha Zeegers, Hsien Shang, Chi-Liang Chen, Mau-Tsu Tang, Ming-Jye Wang, Yun-Liang Soo, Elisa Costantini, Ioanna Psaradaki, Daniele Rogantini
High Energy Astrophysical Phenomena
Abnormal Nitrogen Abundance in the X-ray Spectrum of Quasi-periodically Erupting Source AT2019wzc
Tao Wu, Xinwen Shu, Luming Sun et al. (+3 more)
Quasi-periodic eruptions (QPEs) are rapid, recurring soft X-ray bursts, whose nature is still in dispute. A compelling case of QPEs has emerged in the slowly evolving optical transient AT2019wzc, possibly associated with the
tidal disruption of a post-main-sequence
star by a supermassive black hole. Further evidence of a
tidal disruption event (TDE) is crucial to understand the nature of AT2019wzc and establish the link between TDE and QPEs. Here we report the detection of a narrow, blueshifted N VI absorption line in its high-resolution X-ray spectra obtained by XMM-Newton, but weak or undetectable absorption lines from other elements of similar ionization states such as carbon and oxygen. The absorption line features can be reproduced by an ionized gas with ionization parameter $\log \xi \sim 0.3\ {\rm erg~cm~s^{-1}}$ and column density $N_{\rm H}\sim 10^{20}\ {\rm cm^{-2}}$, under the condition of a nitrogen abundance of $11.6_{-7.8}^{+19.6}$ times the
solar value. This abnormal nitrogen abundance favors a TDE origin for AT2019wzc, and the absorbing gas may originate from the
outflow induced by self-collision of the TDE's debris stream.
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All authors Tao Wu, Xinwen Shu, Luming Sun, Ning Jiang, Jiazheng Zhu, Wenjie Zhang
Physics and Society · Cross-listed from math.CO
Jane Ivy Coons and Giulio Zucal
Discrete Forman-
Ricci curvature is a quantity associated to each edge of a graph that describes its local geometry. It has proven to be a useful tool in network analysis in a variety of applications. Recent work by Roost et al.\ (2024) proposed the use of Markov bases to sample from the space of graphs with prescribed vertex degrees and
curvatures. In the present work, we further develop the algebraic and combinatorial theory of these Markov bases. We show that the degree of an indispensable Markov move grows at least quadratically in the maximum degree of the graph. In light of this result, a compact description of all Markov basis elements seems unattainable at present. Instead, we find a
lattice basis for this problem using only degree three Markov moves, which allows us to employ recently-developed reinforcement learning methods for finding Markov moves that can be applied to a specific graph.
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Soft Condensed Matter
A numerical study to analyze the interplay of Weissenberg number and viscosity ratio in a log-strain tensorial model for viscoelastic fluids
Nehal Dash, Ramon Codina and Giulio G. Giusteri
We present a computational study aimed at exploring the different and independent roles of the Weissenberg number and of the ratio between the polymeric and solvent viscosity contributions in a viscoelastic fluid model. The tensorial model under investigation, recently proposed, is based on a logarithmic relation between the elastic (or recoverable) strain and the elastic stress. In this model, the elastic strain plays the role of a conformation tensor and its
evolution equation inherently preserves its determinant and positive definiteness. These properties are also enforced in the computational method employed in the study. A finite-difference discretization in time is combined with a stabilized mixed finite element formulation based on the Variational Multiscale method for the spatial discretization and with a generalized Lie derivative approach for the advection terms. The behavior of the model is analyzed in paradigmatic pressure-driven flows and we find that the value of the viscosity ratio is crucial in determining to which extent non-Newtonian flow profiles are observed upon increasing the Weissenberg number. By comparing the solutions of the log-strain tensorial model with those of a suitable Generalized Newtonian Fluid model, we show that flow-type dependence and
memory play a significant role even in the simple planar flow past a cylinder.
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Solar and Stellar Astrophysics
The location and propagation of fine structures in type II solar radio bursts
S. Normo, K. Bhandari, A. Nadiger et al. (+1 more)
Solar eruptions such as coronal mass ejections can drive collisionless shocks that are good particle accelerators. Electrons accelerated by these shocks can be observed remotely via the electromagnetic emission they generate at low
radio frequencies. The
radio signatures of shock-accelerated electrons at the Sun are type II
radio bursts that can be used to track the propagation of the shock wave in the
solar corona and beyond. However, type II
radio bursts can have complex morphologies in dynamic spectra, being composed of numerous fine time and frequency structures. Here, we aim to determine the location and propagation of the fine structures composing type II bursts using
radio imaging from the Nançay Radioheliograph. We investigate the origin of a type II
radio burst that was only co-temporal with a
flare and a coronal wave, and it was not associated with a CME eruption. The type II burst still showed complex morphology. We find that emission lanes and fine structures composing the type II burst originate from multiple locations around the
flare site. The source regions also move in peculiar non-uniform propagation directions following the shock expansion. Our findings are consistent with the idea that multiple
radio emission source regions form as a shock propagates through the
solar corona.
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All authors S. Normo, K. Bhandari, A. Nadiger, D. E. Morosan
Cosmology and Nongalactic Astrophysics
Boosting the optical depth to Thomson scattering with primordial black hole evaporation at high redshift
Isaac Sierra, Gabriel P. Lynch, Lloyd Knox et al. (+3 more)
BAO and CMB data are somewhat discrepant when interpreted in the context of $\Lambda$cdm, discrepancies that show up as a `matter density deficit' and as a `CMB
lensing excess'. One possible resolution is an increased optical depth to scattering off of free electrons in the post-recombination universe, $\tau$, a possibility raised by Sailer et al. 2025 and Jhaveri et al. 2025. Since Planck measurements of the low-$\ell$ polarization `reionization bump' already constrain $\tau$ from standard
stellar-driven reionization at $z<10$, we investigate additional optical depth sourced by transient or partial reionization at higher
redshift from exotic processes. For specificity, we explore the impact of Hawking radiation from a monochromatic spectrum of
primordial black holes, retaining the high-$\ell$ $TT/TE/EE$ data that constrain such histories and varying the reionization
redshift jointly. We find that the CMB data do not significantly prefer these additional signals: the boost is at most $\Delta\tau \simeq 0.008$, well short of the $\Delta\tau \simeq 0.03$ that would completely eliminate the moderate discrepancy. The matter density deficit and the
lensing excess are not significantly eased: we explain why, tracing it to compensation from the reionization
redshift and the residual PBH signal at $\ell > 30$.
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All authors Isaac Sierra, Gabriel P. Lynch, Lloyd Knox, Vivian Poulin, Lennart Balkenhol, Ali Rida Khalife
Atomic Physics
Interspecies clock comparison below $5 \times 10^{-18}$ uncertainty with a transportable clock
Chetan Vishwakarma, Ingo Nosske, Tim Lücke et al. (+6 more)
We report a measurement of the optical frequency ratio between the $^2\mathrm{S}_{1/2}(F=0)$–${^2\mathrm{F}_{7/2}(F=3)}$ electric-octupole (E3) transition of $^{171}$Yb$^{+}$ and the $^1\mathrm{S}_0$–${^3\mathrm{P}_0}$ transition of $^{87}$Sr, $\nu_{\mathrm{Yb}^{+}}/\nu_\mathrm{Sr} = 1.495\,991\,618\,544\,900\,588\,1(65)$. Reaching a fractional uncertainty of $4.3 \times 10^{-18}$, this result improves upon the previous best by more than a factor of three and is among the few that meet the requirements for interspecies clock comparisons specified by the roadmap towards the redefinition of the SI second. The comparison is between a transportable optical
lattice clock and a stationary single-ion clock. It spans a period of nearly two years, during which the transportable clock was intermittently operated off-campus. The ratio was reproducibly measured during four separate campaigns, which are consistent within their statistical uncertainties. The results demonstrate reproducible $10^{-18}$ level operation of the transportable clock and thus validate its application for chronometric geodesy and as a transfer standard for inter-institute clock comparisons, e.g., in the absence of optical fiber links.
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All authors Chetan Vishwakarma, Ingo Nosske, Tim Lücke, Martin Steinel, Melina Filzinger, Erik Benkler, Sören Dörscher, Nils Huntemann, Christian Lisdat
Quantum Physics
Optimality of Gaussian Entanglement of Formation
Gerardo Adesso
We prove that the
entanglement of formation of every two-mode Gaussian state coincides with its Gaussian restriction, solving a longstanding open problem in continuous variable
quantum information theory. The key result is a sharp affine relation between
entanglement and a generalized Einstein–Podolsky–Rosen observable, valid for arbitrary pure two-mode states, including non-Gaussian ones. We further prove that the
entanglement of formation is additive on arbitrary tensor products of two-mode Gaussian states, and hence coincides with the
entanglement cost, settling the latter for all two-mode Gaussian states. As a consequence, we obtain in closed form the
entanglement cost of thermal-loss, thermal-amplifier and additive-noise bosonic channels. Our results, which also extend to bisymmetric multimode states, establish that no two-mode state is less entangled than the Gaussian state with the same covariance
matrix, yielding measurable lower bounds on both the
entanglement of formation and the
entanglement cost of arbitrary non-Gaussian states.
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Astrophysics of Galaxies
The TNG50-SKIRT Atlas: Spatially resolved synthetic galaxies from the ultraviolet to the submillimetre (DR2)
Maarten Baes, Paul Vauterin, Abdurro'uf et al. (+20 more)
We present the second data release (DR2) of the TNG50-SKIRT Atlas (TSA), a library of synthetic, spatially resolved
galaxy observables. The atlas is constructed by post-processing a
stellar-mass-complete ($10^{9.8}~{\text{M}}_\odot < M_\star < 10^{12}~{\text{M}}_\odot$) sample of 1154 $z=0$
galaxies from the TNG50 cosmological hydrodynamical simulation with the Monte Carlo radiative transfer code SKIRT. Compared to the first release, TSA DR2 extends the wavelength coverage from the ultraviolet to the submillimetre, including
dust emission, and incorporates updated
stellar population models together with an improved treatment of
dust-enshrouded
star-forming regions. The atlas provides spatially resolved spectral energy distributions, broadband images, and physical property maps for multiple viewing orientations, as well as a catalogue of integrated properties enabling direct comparison with unresolved observations. We validate the data products through extensive quality control, including an assessment of Monte Carlo noise, and demonstrate their internal consistency using diagnostic relations between luminosities and
star formation rates. TSA DR2 provides a versatile resource for studies of
dust attenuation and emission,
star formation tracers,
galaxy morphology, and multi-wavelength scaling relations across spatial scales. The atlas and associated data products are publicly released and are intended to support a wide range of observationally oriented studies of
galaxy evolution.
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All authors Maarten Baes, Paul Vauterin, Abdurro'uf, Nick Andreadis, Thiago Bueno-Dalpiaz, Sena Bokona Tulu, Peter Camps, Abdissa Tassama Emana, Jacopo Fritz, Andrea Gebek, Anand Utsav Kapoor, Inja Kovačić, Arno Lauwers, Kosei Matsumoto, Karín Menéndez-Delmestre, Aleksandr V. Mosenkov, Angelos Nersesian, Lara Pantoni, Mariana Rivas Sánchez, Waad Saftly, Samir Salim, Marko Stalevski, Qi Zeng
Materials Science
Machine Learning Assisted Design of Complex and High Entropy Alloys by Hybrid HiPIMS/Pulsed-DC PVD Process for Low Carbon Energy Applications in Extreme Environments
Paul Foulquier, Ryma Haddad, Ali Mahmoud et al. (+4 more)
Complex and high
entropy alloys are attracting much
attention currently thanks to their mechanical and corrosion resistance properties in harsh environments, in particular needed for carbon-free energy applications. However, their elaboration in bulk and in thin film form in a trial-and-error approach is impractical due to their complexity and the cocktail effect. The recent development of artificial intelligence brings a new possibility for their elaboration and adjustment of their properties. Firstly, we present an overview of Materials and data science research. Then we describe how DIADEM - French initiative for Materials and Data science convergence - tackles the development of innovative coatings for carbon-free energy applications (
nuclear, high temperature electrolysis, ...) thanks to the development of a nationwide network of synthesis and characterization platforms - the DIADEM discovery hub. We describe in particular DIADEM-2D, an AI-driven Hybrid HiPIMS/Pulsed-DC PVD process using 4 cathodes in confocal combinatorial configuration. We present the high
entropy alloy determination using data from the literature for corrosion resistance in molten salt media and
nuclear accidental conditions. An element-independent model gathering deposition parameters and coating properties has been implemented allowing the design of protective coatings with a particular composition. We demonstrate the feasibility of this process and its accuracy.
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All authors Paul Foulquier, Ryma Haddad, Ali Mahmoud, Eric Monsifrot, Fanny Balbaud-Celerier, Jean-Philippe Poli, Frederic Schuster
Mesoscale and Nanoscale Physics
Wannier-Stark localization, confinement and edge states
N. Aucar Boidi, A. Aharony, O. Entin-Wohlman et al. (+1 more)
The boundary between a system's bulk and the
vacuum can be modeled by a potential which confines the electrons to the bulk. Here we present the example of the Wannier-Stark linear potential, generated by an electric field along one axis of a two-dimensional
lattice. Along that axis, the potential generates electronic states which are localized around each
lattice site, with eigenenergies which form the Wannier-Stark ladder. In the transverse direction, the states are governed by a tight binding model with free Bloch states. In the ground state, filling these states under the Pauli principle generates an insulating bulk and an edge which can be metallic in the transverse direction. This paper explains the concepts of localization, localization length, filling and confinement. The paper also acquaints the readers with the use of Bessel functions in the solution of a simple physical model. These topics can be easily included in courses on solid state physics, and only require prior knowledge of
quantum mechanics.
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All authors N. Aucar Boidi, A. Aharony, O. Entin-Wohlman, C.Proetto
Nuclear Theory
Necessary and sufficient conditions of nonlinear causality in viscous anisotropic hydrodynamics
Kento Yoshida, Shujun Zhao and Tetsufumi Hirano
We derive the necessary and sufficient conditions for nonlinear causality in viscous anisotropic hydrodynamics (VAH) within the approximation that neglects small correction terms. Relativistic hydrodynamics provides a successful description of the space-time
evolution of the matter produced in relativistic heavy-ion collisions, yet the earliest stage at which a hydrodynamic description becomes valid remains an open question. VAH has been proposed as an extension of conventional viscous hydrodynamics (VH) that can accommodate the large pressure anisotropies of the early-time dynamics. However, in such far-from-
equilibrium regimes, the nonlinear causality of the theory is not guaranteed. By analyzing the characteristic velocities of the VAH equations of motion, we derive a set of inequalities that ensures causal signal propagation in all directions. The resulting conditions take a remarkably simple form and admit a clear physical interpretation in terms of the characteristic modes of the anisotropic medium. These results establish the regime of validity of VAH and provide a foundation for its application to the early-time dynamics of relativistic heavy-ion collisions.
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High Energy Physics (Phenomenology)
A quality-coupling relation in chiral $U(1)_{B-L}$ axion model
Yu-Cheng Qiu
The quality of the QCD
axion can be protected by a gauge
symmetry. This work considers a gauged
chiral $U(1)_{B-L}$. The
vacuum expectation values of two complex scalars break $U(1)_{B-L}$. One linear combination of their two phase degrees of freedom is eaten by the $U(1)_{B-L}$ gauge
boson, while the other becomes the QCD
axion. Since the PQ
symmetry is accidental, there is no ambiguity in the PQ charge assignment. High
axion quality implies a large anomalous coupling between the
axion and the $U(1)_{B-L}$ gauge
boson (or gauged Majoron). A `quality floor', namely a minimal coupling determined by the
axion quality, arises for the coupling between the
axion and SM
fermions, extending the parameter space of QCD
axions toward improved testability.
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General Relativity and Quantum Cosmology
A Time-Dependent Canonical Transformation between Bateman and Doubled Caldirola–Kanai Systems for a Homogeneous Massive Scalar Field on a Prescribed FLRW Background
Narakorn Kaewkhao and Chaiyaphat Phantusen
Dissipative equations admit distinct variational descriptions in the Bateman and Caldirola–Kanai (CK) formalisms. The classical correspondence between them is extended to a homogeneous canonical scalar field on a prescribed spatially flat Friedmann–Lemaître–Robertson–Walker (FLRW) background, where the expansion produces the time-dependent damping coefficient $3H(t)$. A multiplier action yields the Klein–Gordon equation and a complementary anti-damped equation containing the term $-3\dot{H}(t)\chi$. A first-order Bateman Lagrangian derived from the same multiplier action reproduces this physical–auxiliary pair for a general potential. Specializing to a free massive field gives the Bateman and doubled CK Lagrangians and
Hamiltonians used in the canonical comparison. The factors $a^{3}(t)$ and $a^{-3}(t)$ generate the damped and anti-damped CK sectors, respectively. An explicit time-dependent canonical transformation, generated by a function linear in the Bateman momenta, maps the complete doubled CK system to the Bateman system. For this point transformation, the terms proportional to $\dot{H}(t)$ are required for
Hamiltonian equivalence. In rotated variables, the Bateman scalar-field
Hamiltonian takes the difference form $H_{B,\mathrm{SF}} = E_{u} - E_{v}$. It is conserved for constant $H$ and generally varies with time otherwise. For the power-law background $a(t) \propto t^{p}$, however, a correlated family at $p = 2/3$ has conserved $H_{B,\mathrm{SF}}$ despite the time dependence of $H(t)$. These results concern classical homogeneous fields on a prescribed FLRW background and exclude the gravitational phase space.
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Strongly Correlated Electrons
Microscopic magnetic phase evolution in the Weyl semimetal Mn$_3$Sn revealed by $\mu^+$SR
U. Miniotaite, O. K. Forslund, H. Luetkens et al. (+8 more)
We report a comprehensive
muon spin relaxation ($\mu^+$SR) and bulk magnetization study of the
antiferromagnetic (AFM) Weyl semimetal Mn$_3$Sn (composition Mn${2.99}$Sn). Mn$3$Sn is reported to exhibit a commensurate inverse triangular (IT) AFM phase, an incommensurate (IC) helical AFM phase, and a proposed low-temperature
spin-glass-like state. In our sample, we identify the characteristic temperatures associated with these regimes as N'eel temperature ($T\mathrm{N} = 418$ K), a macroscopic bulk transition temperature between IT-AFM to IC helical phase ($T\mathrm{t} \approx 275$ K), and low-temperature transition $T_\mathrm{f} = 21$ K. Investigating the low-temperature regime below $T_\mathrm{f}$, we find no evidence of a static
spin-glass state. Instead, the sample exhibits an increasing
ferromagnetic (FM) component accompanied by a localized slowing of
spin fluctuations, indicating that these phenomena may be decoupled. In the IC helical AFM phase, the zero-field (ZF) spectra are best described by damped oscillations with an empirical phase offset, consistent with anharmonic and amplitude-modulated order reported by scattering studies. Upon warming above 150 K, a continuous redistribution of
muon spectral weight reveals a broad, homogeneous
magnetic crossover between the IC helical and IT-AFM phases. In the commensurate IT-AFM phase above $T_\mathrm{t}$, a persistent missing fraction in the initial asymmetry indicates that a subset of implanted
muons, corresponding to roughly 20% of the sample-related asymmetry, undergoes unresolved ultrafast depolarization. Finally, we observe temperature-driven shifts in
muon site populations above 325 K. Ultimately, our results show a highly dynamic
magnetic landscape in Mn$_3$Sn, demonstrating how its complex
magnetic orders often coexist and evolve continuously with temperature.
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All authors U. Miniotaite, O. K. Forslund, H. Luetkens, V. Rai, J. Persson, G. D. Morris, D. Zuhair, D. W. Tam, S. Nandi, Y. Sassa, M. Månsson
High Energy Physics (Phenomenology)
Thermal Leptogenesis in the Babu-Nandi-Tavartkiladze Model of Neutrino Mass
P. S. Bhupal Dev, Srubabati Goswami, Debashis Pachhar et al. (+1 more)
We investigate
neutrino mass and thermal leptogenesis in the Babu-Nandi-Tavartkiladze (BNT) model featuring a scalar quadruplet ($\Phi$) and a pair of vector-like
fermion triplets ($\Sigma$). In this framework,
neutrino masses are generated via an effective dimension-7 operator $LLHH(H^{\dagger}H)/\Lambda^3$ at the tree level and via the dimension-5 operator $LLHH/\Lambda$ at the one-loop level. It naturally accommodates sub-eV
neutrino masses even if the new physics scale $\Lambda$ is $\mathcal{O}(\rm TeV)$, thus making the model a compelling target for experimental searches. We explore the viability of thermal leptogenesis in this model, which is distinct from the canonical seesaw-based leptogenesis due to the presence of vector-like
fermions. We find that leptogenesis is viable for $M_\Sigma \gtrsim 10^{7}$ GeV for a hierarchical spectrum of
fermion triplets. However, in the quasi-degenerate regime, resonant enhancement of the $CP$ asymmetry lowers this scale down to $\mathcal{O}({\rm TeV})$, reconciling successful leptogenesis with the originally motivated TeV-scale phenomenology and testability of the model at
colliders.
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All authors P. S. Bhupal Dev, Srubabati Goswami, Debashis Pachhar, Drona Vatsyayan
High Energy Physics (Phenomenology)
Measuring the trilinear Higgs self-coupling in Higgs boson pair production at multi-TeV muon colliders
Kingman Cheung, Jae Sik Lee, Soojin Lee et al. (+1 more)
The trilinear
Higgs self-coupling determines the shape of the
Higgs potential, and its measurement is a central goal of future
colliders. We assess the sensitivity of multi-TeV
muon colliders to the coupling modifier $\kappa_3$ in
Higgs boson pair production via vector
boson fusion, using the $b\bar{b}b\bar{b}$ final state at $\sqrt{s}=3$ TeV with $1$ ab$^{-1}$ and at $10$ TeV with $10$ ab$^{-1}$. Events are analyzed in two complementary regions, a resolved region with four jets and a boosted region with two large-radius jets. To extract the signal from backgrounds a few orders of magnitude larger, we combine a supervised jet-to-
Higgs pairing network based on the SPANet approach, topological data analysis of the event energy flow, and two dedicated classifiers, $D_{\rm HH}$ for the signal-to-background separation and $D_{\kappa_3}$ for the $\kappa_3$ shape information. The coupling is extracted from a two-dimensional likelihood fit to the distribution of the two classifier outputs. Combining the two regions, we obtain $0.80<\kappa_3<1.29$ at $3$ TeV and $0.96<\kappa_3<1.05$ at $10$ TeV at $68\%$ confidence level. The $10$ TeV determination reaches the few-percent level in this statistics-limited projection, which surpasses by a large amount the precision projected for the HL-LHC.
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All authors Kingman Cheung, Jae Sik Lee, Soojin Lee, Chen Wang
Quantum Physics
The Pangaea Architecture: Fault-Tolerant Heterogeneous Topological Codes via a Quantum Bus
Sheir Yarkoni, Chen Scheim, Daniel Hakshuri et al. (+1 more)
We introduce Pangaea, a fault-tolerant
quantum architecture that uses a
quantum bus to mediate logical operations between remote patches of two-dimensional topological codes. The bus is an auxiliary gauge-code strip whose measurements reconstruct joint logical operators while preserving nearest-neighbor physical connectivity. Enabling native heterogeneous topological codes and multi-
qubit Pauli operations, the
quantum bus can be interpreted as a three-dimensional generalization of
lattice surgery. We require only $O(dN_L)$ physical
qubits to implement multi-
qubit interactions for $N_L$ distance-$d$ logical
qubits, compared to $O(d^2N_L)$ of traditional two-dimensional architectures. At the 50-logical-
qubit scale, Pangaea uses up to $10\times$ fewer physical
qubits than planar surface-code architectures at matched logical error rates. We verify fault-tolerance of long-range measurement-based CNOT primitives for both surface–surface and surface–color joint parity measurements using pseudo-threshold simulations. We use this protocol to construct a native heterogeneous 15-to-1 magic-state
distillation module using the
quantum bus. These results establish Pangaea as a scalable architecture for three-dimensional fault-tolerant
quantum computing that resolves the routing bottleneck of planar
lattice surgery.
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All authors Sheir Yarkoni, Chen Scheim, Daniel Hakshuri, Nadav Katz
Strongly Correlated Electrons
Diodes and capacitors for the transport of monopoles in fragmented spin ice
Anoop Raj, Sumiran Pujari and Ludovic D.C. Jaubert
Spin-ice materials are famous for their quasi-particle excitations that behave like
magnetic monopoles. Magnetricity is the concept that these monopoles can conduct an AC
magnetic current, in analogy with conduction electrons. While monopole dynamics has been intensively studied and is reasonably well understood, very little has been done to design devices in order to control magnetricity. Here we develop a theoretical proof of concept for the design of diodes and capacitors for the transport of monopoles. We use the property of systems with
magnetic fragmentation, where
spin-ice physics co-exists with long-range
antiferromagnetic order. The key point is that
magnetic order allows for the existence of domain walls. Under certain conditions of preparation, this domain wall is equivalent to an asymmetric filter for monopoles. In a given direction, positive charges can go through while negative ones are repelled; the opposite applies in the opposite direction. This asymmetry effectively functions like a diode for monopole current. Successive domain walls separate positive from negative charges with a
vacuum of charge in between, producing a capacitor for monopoles. Once the capacitor is charged, it can in principle be used as a battery for monopoles. All microscopic mechanisms are explained and our proof of concept is validated by simulations of more than a million
spins. Application to experiments are discussed for rare-earth pyrochlore
oxides and artificial
spin ice. Finally, we discuss in general terms how a domain wall in fragmented
spin ice can also be seen as an emergent boundary separating two mirror "worlds" separated by time-reversal
symmetry. Beyond
spin ice, our work opens a promising direction of investigation for the dynamics of emergent quasi-particles crossing domain walls in
chiral and nematic
spin liquids, which also possess a broken
symmetry.
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Statistical Mechanics
Gap distributions between successive personal bests in cricket: Data and Models
Priyanka D. Bhoyar and Prashant M. Gade
Successive personal best performances provide a natural measure of progression in an athlete's career. Classical record theory predicts a universal gap distribution, $P(g)\sim 1/g$, for independent and identically distributed (i.i.d.) sequences. However, sporting careers are shaped by learning, aging, changes in ability, and external influences that violate these assumptions. We investigate the statistics of inter-record gaps, defined as the number of innings between successive personal best scores, in cricket. Using career records of leading Test, ODI, and T20 players obtained from ESPN Cricinfo. We find that the empirical distributions are well described by truncated power law $P(g) \propto g^{-\alpha} e^{-\lambda g}$ with exponents in the range (0.799 $\leq \alpha \leq$ 0.843). Much of this deviation disappears when the temporal ordering of innings is destroyed, indicating that career
evolution plays a key role in shaping record occurrence. Bootstrap-shuffled careers, which preserve individual score distributions and career lengths while removing temporal ordering, yield significantly larger exponents ($\alpha \approx 0.939\text{--}0.979$). These findings show that the progression of personal best performances retains information about the temporal organization of a player's career and cannot be fully explained by simple
stochastic record processes. More generally, they illustrate how record statistics are altered in nonstationary and path-dependent systems.
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Mathematical Physics
Collective superintegrable systems from the Guillemin–Sternberg torus action
L. Feher
We present a novel approach to the superintegrability of collective
Hamiltonians invariant under a
Hamiltonian action of a connected semisimple compact Lie group, $G$, on a
symplectic manifold, $M$. By exploiting a
Hamiltonian torus action that goes back to Guillemin and Sternberg [GS,1983], we demonstrate that the functional dimensions of $\mathfrak{H} := \mathcal{J}^*(C^\infty(\mathfrak{g}^*)^G)$, where $\mathcal{J}: M \to \mathfrak{g}^*$ is the momentum map of the $G$ action, and its centralizer $\mathfrak{F}$ in $C^\infty(M)$ satisfy the equality $\mathrm{ddim}(\mathfrak{H}) + \mathrm{ddim}(\mathfrak{F}) = \mathrm{dim}(M)$. Together with a non-triviality condition, this ensures that the Abelian Poisson
algebra $\mathfrak{H}\subset C^\infty(M)$ represents a superintegrable system, and it also follows that the momentum map of the GS
torus action yields action variables for the system. Our work provides a new insight into collective superintegrability complementing earlier results of Bolsinov and Jovanović.
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Accelerator Physics
Machine Learning Optimization of E-Beam Transport for a Superradiant FEL
Amir Weinberg, Leon Feigin, Ariel Nause et al. (+1 more)
We present an optimization procedure using machine learning (ML) libraries for optimization of electron beam transport for maximal bunch compression and optimal operation of a bunched-beam Superradiant FEL. This is exemplified for the parameters of the 6MeV ORGAD Accelerator at Ariel University that is driving a THz Superradiant waveguide FEL. For superradiant emission (proportionally to the number of electrons squared), the bunch duration ${\sigma}_t$ at the undulator should be shorter than the optical period (2${\pi}/{\omega}$) of the radiation. Also, the beam transport optimization must confine the transverse dimensions of the beam to enter the undulator waveguide. The variables of the ML
Bayesian optimization are the RF parameters and the currents of the coils and quads along the beamline. The beam dimensions and duration are provided from full 3D GPT simulations that are automatically driven by the ML exploration and exploitation
algorithms. Twenty-five simulation iterations sufficed to arrive to an optimal beam transport design.
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All authors Amir Weinberg, Leon Feigin, Ariel Nause, Avraham Gover
General Relativity and Quantum Cosmology
Analytically Approximate Black Hole Solution to Higher Curvature Gravity
Seyed Naseh Sajadi
Higher-
curvature gravity usually leads to very complicated field equations, which makes it hard to find analytical solutions. In this work, we obtain analytical charged black hole solutions in higher-
curvature gravity by using black hole thermodynamics and the continued fraction expansion. We study the thermodynamics of static black holes using the first law of thermodynamics and the Smarr formula. We show that our results agree with those obtained by directly solving the field equations in Einstein
gravity.
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Astrophysics of Galaxies
Projection Effects in Merger Dating for Illustris TNG Shell Galaxies
Tuğba Erol, Mustafa Kürşad Y{\i}ld{\i}z, Ivana Ebrová et al. (+1 more)
Stellar shells are low-surface-brightness structures that typically appear as concentric arcs. They are observed in many
giant elliptical and lenticular
galaxies, as well as in some spiral and
dwarf galaxies. They presumably result from minor and intermediate close-to-radial mergers of
galaxies. An essential factor in determining the merger time are the distances of shells from the centre of the
galaxy. Consequently, estimates of the merger time can be significantly affected if some shells remain undetected due to projection effects. In this study, we present the first systematic investigation of how measured shell radii depend on the orientation of a
galaxy relative to the observer. Using the Illustris TNG50 simulation, we examine shell
galaxies from nine selected lines of sight and measure the shell radii. We model shell
evolution and calculate the merger time accordingly for each viewing angle and quantify the impact of orientation on the inferred merger age. Our results indicate that the line of sight can have a substantial effect on merger-time estimates derived from shell radii.
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All authors Tuğba Erol, Mustafa Kürşad Y{\i}ld{\i}z, Ivana Ebrová, Michal Bílek
Atmospheric and Oceanic Physics · Cross-listed from stat.AP
Probabilistic Deep Learning for Drought Forecasting: Role of Internal Climate Variability
Henri Funk, Cornelia Gruber, Göran Kauermann et al. (+2 more)
Predicting drought risk is essential for anticipating impacts on water resources, agriculture, ecosystems, and
climate adaptation planning. Yet drought forecasts remain uncertain because variability can substantially alter regional precipitation and evaporative demand. Treating this variability as unstructured noise ignores the fact that internal variability has spatial, seasonal, and temporal structure and thus contains information that can be used to improve drought
forecasting. We propose a deep-learning-based
forecasting framework for European drought prediction and extend it with an uncertainty-aware drought bound that explicitly incorporates internal forecast variability from a large
climate model ensemble. This bound represents a physically plausible lower-tail trajectory of future drought conditions and marks how severe drought could plausibly become under an unfavourable realisation of internal variability, giving adaptation planning a conservative, risk-averse reference. We compare the proposed bound with a lower bound derived from reanalysis data only and show that our proposed ensemble-informed bound is better calibrated across most regions and seasons. This is specifically true during anomalously dry conditions, when historical reanalysis alone underestimates lower-tail drought risk. Our results show that internal variability should be treated as a forecast quantity in its own right. More broadly, large ensembles provide a practical way to transfer physically plausible
climate variability into machine-learning drought forecasts, yielding risk-aware bounds that are more informative for drought assessment under shifting
climate conditions.
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All authors Henri Funk, Cornelia Gruber, Göran Kauermann, Helmut Küchenhoff, Magdalena Mittermeier
Physics and Society
Local network growth: How simple rules drive network complexity
Alexei Vazquez
The Internet, a living
cell, a circle of friends, a billion-dollar construction project: these systems share almost nothing – yet, drawn as networks, they look astonishingly alike. Each has a few
giant hubs among a multitude of sparsely connected nodes, short paths between any two parts, dense local clustering, communities, and many redundant routes. For two decades such patterns have been credited to "preferential attachment," the rich getting richer – a rule that, taken literally, asks every newcomer to survey the whole network before it links. This book makes a simpler case, and defends it one mechanism at a time: the global regularities of real networks are not imposed from above but emerge from purely local rules, in which each new node acts only on a node it has reached and that node's immediate neighbours. A surfer following links, a friend introducing a friend, a gene copied with its connections – none consults the network as a whole, yet each builds, in the aggregate, the full and unmistakable signature of a real complex system. Written for the curious reader as much as the specialist, with the ideas told in plain
language and the mathematics set aside in boxes that can be skipped, it shows how citation graphs, the web, social ties,
protein interactions, and project schedules all grow themselves from the same handful of local rules – one local decision at a time.
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Cosmology and Nongalactic Astrophysics
Revisiting Metastable Dark Energy in Light of DESI DR2 BAO and DESI DR1 Full-Shape Measurements
Purba Mukherjee, Arman Shafieloo and Varun Sahni
We revisit metastable dark energy (DE) models described by a radioactive-like decay law. We consider three scenarios: an effective, exponentially decaying DE component; decay of DE into non-baryonic dark matter (DM); and decay of DE into dark radiation (DR). We constrain the metastable DE models using DESI DR2
baryon acoustic oscillation (BAO) data, Type Ia
supernovae (SNIa),
cosmic microwave background (CMB) observations, and, for the first time, the current available DESI DR1 full-shape (FS) clustering measurements. The BAO+SNIa combinations show a mild preference for positive $\Gamma/H_0$, with a deviation from the $\Lambda$CDM limit at the $\gtrsim 2\sigma$ level. This corresponds to a decaying DE density and an effective quintessence-like behaviour at low
redshift. Once CMB information from either Planck or P-ACT is included, however, the constraints become statistically consistent with $\Gamma/H_0=0$. The FS measurements probe the growth sector and help distinguish the interacting DM-DE behaviour of Model 2 from the effective decaying-DE response of Model 1 and the weaker DR-induced response of Model 3. For CMB+FS+DES-Dovekie, Model 1 shows a slight deviation from $\Gamma/H_0=0$ at the $\gtrsim 2\sigma$ level, while Models 2 and 3 remain consistent with the $\Lambda$CDM limit within $2\sigma$. Overall, metastable DE remains phenomenologically viable: current data allow late-time dynamics but do not provide decisive evidence for a nonzero decay rate. These results motivate extending our analysis to the upcoming DESI DR2 FS data to obtain tighter constraints on metastable dynamics.
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