High Energy Astrophysical Phenomena
Relativistic Magnetohydrodynamics from Myers-Pospelov Lorentz-Violating Electrodynamics
Matheus Duarte and Vitor de Souza
We derive the equations of relativistic magnetohydrodynamics from Lorentz-violating Myers-Pospelov electrodynamics. Starting from the modified fermionic and electromagnetic equations of motion, we employ the covariant Wigner formalism to establish the semiclassical spectral constraints and distribution function, which, combined with Noether's
theorem, yield the energy-momentum tensor, particle current, and corresponding conservation laws in the presence of Lorentz violation. The resulting hydrodynamic description contains Lorentz-violating corrections to the thermodynamic quantities and to the fluid currents. In the purely timelike sector, these corrections can be absorbed into effective thermodynamic quantities, preserving the isotropic structure of the fluid equations. In contrast, spacelike backgrounds introduce explicit contributions along the preferred direction, which cannot be absorbed into the standard hydrodynamic variables and give rise to anisotropic forces and torques. These effects lead to departures from standard relativistic magnetohydrodynamics and provide a direct macroscopic manifestation of the Lorentz-violating background. Our results provide a first-principles derivation of Lorentz-violating relativistic magnetohydrodynamics and establish a framework for investigating the macroscopic consequences of Lorentz violation in magnetized relativistic fluids.
Read the full abstract ▾
Mathematical Physics · Cross-listed from math.PR
Fourier decay of Gaussian multiplicative chaos and boundary geometry
Marcu-Antone Orsoni and William Verreault
In this paper, we develop a new approach to studying the
Fourier transform of Gaussian multiplicative chaos. We determine the
Fourier dimension of these random measures on
tori for every smooth log-correlated covariance and in every dimension, and prove sharp bounds and exact formulas for chaos on natural classes of bounded sets and hypersurfaces in Euclidean space. These results highlight how boundary geometry and multifractal concentration jointly govern
Fourier decay, including regimes in which the boundary strictly reduces the
Fourier dimension. In the circle setting, this gives a substantially simpler new proof of a
conjecture of Garban and Vargas.
Read the full abstract ▾
Materials Science
Device Engineering and Performance Optimization of Cu2NiGeS4 Thin-Film Solar Cells with In2S3/MoTe2 Charge-Selective Layers: A Computational Study
Md Tashfiq Bin Kashem and Hasib Md Abid Bin Farid
The pursuit of efficient and sustainable thin-film photovoltaics increasingly demands absorber materials that combine strong optical absorption with earth-abundant and environmentally benign constituents. Cu2NiGeS4 (CNGS) has emerged as a promising quaternary chalcogenide absorber owing to its favorable optoelectronic properties and high absorption coefficient, yet its photovoltaic potential remains comparatively underexplored, particularly in conjunction with optimized charge-selective layers. Here, we introduce and comprehensively investigate an CNGS-based
solar-
cell architecture using SCAPS-1D, with In2S3 and MoTe2 serving as the electron and hole-transport layers respectively. The analysis of energy-band profiles, electric fields, carrier distributions, and generation-recombination characteristics reveals the mechanisms governing carrier separation and extraction across the heterojunctions. Systematic optimization of layer thickness, doping density, bulk and interface defect densities, recombination coefficients, parasitic resistances, temperature, and illumination intensity identifies the key factors limiting device performance. The optimized device is predicted to achieve a power conversion efficiency (PCE) of 28.44% with a open-
circuit voltage (VOC) of 0.984 V, short-
circuit current density (JSC) of 34.39 mA/cm2, and fill factor (FF) of 84.04%, under AM1.5G illumination at 300 K. This simulated efficiency exceeds the previously reported 6.25-21.17% range for CNGS-based
solar cells considered in this study. The findings establish In2S3/CNGS/MoTe2 as a promising platform for next-generation thin-film photovoltaics and provide physically grounded design guidelines for absorber optimization, interface engineering, and future experimental realization.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Might the radiation era extend back to the Big Bang? On dark matter production and the relic graviton background in quadratic gravity
Latham Boyle, Neil Turok and Vatsalya Vaibhav
Naive estimates based on Einstein
gravity with Lagrangian $\frac{1}{2}M_{pl}^{2}(R-2\Lambda)$ suggest that, if the radiation era extended back to the Big Bang (i.e., as far back as the classical spacetime background makes sense), this would result in an over-production of dark matter and a relic
cosmic background of thermal gravitons. Here we revisit these conclusions in quadratic
gravity, the minimal renormalizable completion of Einstein
gravity, whose Lagrangian also includes the terms $\frac{1}{6}f_0^{-2}R^2-\frac{1}{2}f_{2}^{-2}C^{2}$. Assuming the radiation era does extend back to the bang, we find a novel relation between the coefficient $f_{2}$ and the dark matter mass $m_{dm}$, needed to obtain the correct dark matter abundance. This yields a new gravitational production mechanism for dark matter (e.g., stable right-handed
neutrinos). Moreover, the presence or absence of the relic graviton background (detectable by forthcoming CMB experiments via its small imprint on $N_{{\rm eff}}$) will place new constraints on $f_{0}, f_{2}$.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Precise bubble wall velocity in a specific phase transition pattern in the CxSM and beyond
Shihang Tang, Fa Peng Huang and Chikako Idegawa
The bubble wall velocity is a key quantity in cosmological first-order phase transitions, with important implications for electroweak baryogenesis, gravitational wave signals, the dark matter relic density and
primordial black holes formed during the phase transition. However, it is often treated as a free input in phenomenological studies, while a self-consistent determination remains challenging. In this work, taking the complex singlet extension of the Standard Model as an example, we investigate the bubble wall dynamics and velocity in a specific electroweak phase transition pattern where both the
Higgs field and the coupled singlet scalar experience friction. The microscopic friction arising from particle interactions with the
plasma is evaluated using Boltzmann transport equations, while the macroscopic
plasma response is described through hydrodynamic analysis. By applying the steady state force balance condition, we numerically determine the bubble wall velocity for different model parameters. We show that the wall velocity is governed by the competition between the driving force from the effective potential and
plasma friction, and that its variation can significantly affect the
baryon asymmetry. Our study provides a quantitative investigation of bubble wall dynamics in this overlooked phase transition pattern and its implications for early Universe phenomenology.
Read the full abstract ▾
Strongly Correlated Electrons
Unraveling the Kagome Antiferromagnetic $3J$ Model and Its Materials: An Integrated Approach
Xin Lu, Andreas Raikos, Menghan Song et al. (+6 more)
We investigate the ground-state and finite-temperature properties of the kagome
antiferromagnetic Heisenberg model with three inequivalent couplings, dubbed the $3J$ model, which is designed for the candidate Dirac
quantum spin liquid (QSL) material YCu$_3$(OH)$_6$Br$_2$[Br$_{1-x}$(OH)$_x$] (see, e.g., Zeng et al., 2024). Employing large-scale density-
matrix renormalization group (DMRG) supplemented by neural
quantum states (NQS) simulations, we identify an intermediate QSL phase between two magnetically ordered phases. We also find that this QSL is separated from the kagome
spin liquid ground state at the isotropic limit. To establish a direct comparison with experiments, we compute the specific heat of the model by means of advanced exponential (XTRG) and tangent-space (tanTRG) thermal tensor-network methods. In the magnetically ordered phase, the specific heat over temperature exhibits a shoulder at a temperature that is a fraction of the coupling strength $J_{h}$, which disappears in the QSL phase. These universal behaviors are consistent with the experimentally observed specific heat in $3J$ materials for both ordered and QSL candidate samples. Our work thus connects microscopic models with experimentally measurable signatures, exemplifying an integrated approach to understanding QSL phenomena in frustrated
quantum magnets~ (see Meng et al., 2026), with $3J$ materials serving as a representative case and providing a foundation for future studies.
Read the full abstract ▾
All authors Xin Lu, Andreas Raikos, Menghan Song, Zezong Li, Lankun Han, Shiliang Li, Sylvain Capponi, Zi Yang Meng, Chengkang Zhou
Plasma Physics
Experimental Plasma Density Profiles Determined Through Measurements of the Magnetosonic Wave Speed
Cameron Kuchta, Jan Egedal, Abhishek Mhatre et al. (+4 more)
Information on
plasma density in laboratory
plasmas is commonly acquired using either Langmuir probes or optical diagnostics. Here, we present an alternative approach, inferring the density profile from
magnetic measurements of a
plasma wave. In particular, during the process of creating a reconnecting current layer for
magnetic reconnection experiments in the Big Red Ball, the reconnection drive first launches a large amplitude fast magnetosonic wave. The propagation of the wavefront is measured with high spatial and temporal resolutions by in situ
magnetic diagnostics. Given a known uniform background
magnetic field strength and the known dispersion relation of the wave, we here show how the characteristics of the wavefront can be applied to determine the initial
plasma density profile.
Read the full abstract ▾
All authors Cameron Kuchta, Jan Egedal, Abhishek Mhatre, Paul Gradney, Joseph Olson, Xinyu Yu, Cary B. Forest
Quantum Physics
Quantum transport along a tight-binding chain connected to Markovian reservoirs
P. S. Muraev, A. R. Kolovsky and D. N. Maksimov
We consider
quantum transport of non-interacting particles in a tight-binding chain coupled to Markovian reservoirs at its boundaries and subject to uniform on-site dephasing. Using the masterequation approach, we derived the exact analytic solution for the mean current along the chain. This analytic solution is obtained in the framework of single-particle
quantum mechanics and, thus, equally applies for transport of non-interacting
bosons and
fermions. In the absence of phase damping, the results are extended to the complete many-body solution for bosonic problem in the form of anti-normally ordered characteristic function. This function allows us to calculate the distribution function for the current at each bond in the chain as well as the inter-bond current correlation functions.
Read the full abstract ▾
High Energy Physics (Theory)
Fermion quantum field theory on curved and non-inertial backgrounds in standard-Minkowski form
Fabio Di Pumpo, Tobias Asano, Alexander Friedrich et al. (+2 more)
Quantum field theory on curved and non-inertial backgrounds contains background- and foliation-dependent quantities in the canonical Lagrangian, the hypersurface inner product and bilinear form, as well as in the equal-time anti-commutation relations. In this work, we determine a local
fermion-field redefinition that brings these canonical structures into their standard-Minkowski forms, i. e., the forms they assume in Cartesian inertial coordinates on Minkowski spacetime, where the zeroth world coordinate is identified as the coordinate of time. Starting from the generally covariant Dirac action minimally coupled to a
spin-1 gauge field, we derive the corresponding Lagrangian, fermionic inner product, and quantization rule in an Arnowitt-Deser-Misner decomposition, formulated in arbitrary world coordinates. We identify the generalized temporal gamma
matrix as the common
geometric factor governing the canonical temporal structure of all three quantities. Using a field redefinition, we transform this generalized temporal gamma
matrix to its standard-Minkowski form, thereby mapping the fermionic inner product and the equal-time anti-commutation relation to their standard-Minkowski expressions, while transferring the explicit background and foliation dependence to the transformed Lagrangian and
fermion-field operators. We show that such a field redefinition necessarily consists of a local rescaling and a fixing of the local Lorentz frame. This procedure restores the conventional canonical normalization from standard-Minkowski spacetime used for fermionic mode quantization and occupation-number operators. The transformed Lagrangian consequently assumes a generalized first-order Schrödinger form, leading to the familiar rest-energy term and spacetime-
magnetic couplings, as well as to the leading non-relativistic limit, in which temporal derivatives are separated from spatial ones.
Read the full abstract ▾
All authors Fabio Di Pumpo, Tobias Asano, Alexander Friedrich, Gil Paz, Enno Giese
Quantum Physics
Learning structural balance of graphs from quantum spectral features
Stefano Scali and Oleksandr Kyriienko
We develop a
quantum approach to spectral feature extraction from the density of states (DOS) of a problem-dependent
Hamiltonian, and apply it to machine learning on signed graphs. We propose to embed a signed graph as an Ising model instance with positive and negative interactions, and use the standardized moments of the Ising DOS as features for learning. We show that these moments count signed closed walks, are switching-invariant, and are size-free by construction. As a
benchmark, we target learning the frustration index, an NP-hard measure of structural balance that can be labeled exactly at moderate size. At zero field, the models can be sampled classically, allowing the
quantum extraction procedure to be certified against exact ground truth. We propose DOS-QPE, a phase estimation on a purified maximally mixed probe, which samples the spectral density with orders of magnitude fewer shots than Hadamard test-based trace sampling and feeds the resulting features directly into classically trained models. On $1.4\times10^5$ labeled graphs the exact DOS determines the frustration index, and five moments recover it with a mean error of 0.4, well below one sign flip. Beyond zero field, the underlying trace-estimation problem is DQC1-complete, providing access to spectral features for which no efficient classical sampling method is known. Our work opens routes towards
quantum applications in social network balance analysis,
spin-glass studies, correlation clustering, and
protein-interaction networks.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Hilbert-space selected switch of helical edges in an artificial quantum Hall insulator
Naijie Ren, Zhiren Xiong, Kaining Yang et al. (+9 more)
Quantum Hall effects (QHE) host one-dimensional topologically-protected edge channels, which can serve as an essential ingredient in exotic
quantum electronic systems. Yet the manual reconstruction of Landau-level
topology, by electrostatic confinement or
symmetry breaking, remains experimentally challenging. Here, we show that interfacial charge transfer in between CrOCl and large-angle twisted
bilayer graphene offsets the two otherwise decoupled Dirac Landau-level ladders in each
graphene layer, creating a new sequence of composite filling configurations. At charge neutrality, the composited $(+2,-2)$ state involves only the zeroth Landau levels and becomes fully insulating, with longitudinal resistance reaching the G$\Omega$ regime. By contrast, higher composite zero-filling
quantum Hall states, including $(+6,-6)$ and $(+10,-10)$, retain counter-propagating helical edge channels and exhibit pronounced non-local transport, reaching up to $50\%$ of the local response. We attribute such switching-behavior to the Landau-spinor
Hilbert space – as the filling is reduced from $(+6,-6)$ to $(+2,-2)$, the orthogonal $N=\pm1$ orbital components are removed, eliminating the edge-compatible channel and gapping both bulk and boundary transport. The interaction nature of the observed gapped sates was further examined both experimentally and theoretically. Our results suggest that charge transfer provides a direct route to engineer artificial
quantum Hall insulators, opening possibilities for wavefunction-selective control of helical edge modes.
Read the full abstract ▾
All authors Naijie Ren, Zhiren Xiong, Kaining Yang, Yanran Shi, Hanwen Wang, Kenji Watanabe, Takashi Taniguchi, Neng Wan, Xiaojun Jia, Jianpeng Liu, Zheng Vitto Han, Yaning Wang
Quantum Physics
An exchange-assisted entangling gate between 87Rb and 171Yb Rydberg atoms
Han Wang, Erdong Huang, Mingrui Jing et al. (+3 more)
Neutral-atom tweezer arrays support scalable
quantum information processing. Dual-species $^{87}\mathrm{Rb}$–$^{171}\mathrm{Yb}$ arrays combine long-lived ytterbium
nuclear-
spin data
qubits with fast, species-selective rubidium ancilla control and readout. However, realizing interspecies gates without inducing destructive Stark mixing in divalent atoms remains an outstanding problem. Here, we identify an optically accessible $S{+}S\leftrightarrow P{+}P$ Förster resonance at zero electric field, providing strong dipole-dipole exchange at array pitch. Using a shaped optical pulse under finite control response, we demonstrate a $0.36\,\mu\mathrm{s}$ exchange-assisted controlled-$Z$ gate with an intrinsic fidelity of $99.91\%$, remaining above $99.85\%$ under bounded perturbations. We also identify an auxiliary repulsive van der Waals channel, providing a comprehensive toolbox for hybrid
quantum processors.
Read the full abstract ▾
All authors Han Wang, Erdong Huang, Mingrui Jing, Hongshun Yao, Xin Wang, Jinguo Liu
General Relativity and Quantum Cosmology
From the Test-Mass Limit to Binary Black-Hole Waveforms in Higher-Derivative Gravity
Chaoyi Yang, Neev Khera, Dongjun Li et al. (+1 more)
Many higher-derivative theories predict stronger deviations from General Relativity for lower-mass black holes, while their nonlinear field equations often prevent reliable simulations of the full binary
evolution. Here we develop a route from controlled black hole perturbation theory based on the modified Teukolsky formalism to comparable-mass waveforms, using parity-even cubic
gravity as a representative example. We find that the
tidal response of the secondary black hole enters at the same perturbative order as the direct higher-
curvature correction and is therefore essential for a consistent leading-order waveform. The resulting strong-field fluxes and conservative dynamics produce an accumulated inspiral dephasing that grows toward merger.
Embedding this test-mass information into an effective-one-body model, we construct inspiral-merger-ringdown waveforms for comparable-mass binaries and find coupling-dependent dephasing and waveform-peak shifts. Our results demonstrate how strong-field test-mass calculations can anchor waveform models for higher-derivative
gravity when theory-specific numerical-relativity simulations are unavailable.
Read the full abstract ▾
All authors Chaoyi Yang, Neev Khera, Dongjun Li, Huan Yang
Quantum Physics
Lifted surgery: Fast processing with QLDPC codes
Lucas Berent, Lawrence Z. Cohen and Armanda O. Quintavalle
Quantum low-density parity-check (QLDPC) codes are a leading candidate for achieving low-overhead fault-tolerant
quantum computing. However, the time overhead of logical operations in QLDPC codes remains a key challenge. Code surgery, a space-efficient technique for fault-tolerant logical measurements, incurs this overhead through repeated rounds of syndrome measurement. We introduce lifted surgery, a method for fast and parallel surgery on Abelian group
algebra codes that maintains the low physical overhead that makes QLDPC codes attractive. Lifted surgery preserves the
symmetries of the underlying code, making searches for large instances tractable and offering a natural route towards efficient hardware implementations. We utilise block decompositions and techniques from commutative
algebra to characterise lifted surgery, investigate well-behaved subfamilies, and construct explicit examples. In particular, we present
quantum radial codes with parameters $[[90, 8, 10]]$ and $[[198, 8, 16 ]]$ for which surgery is fast, parallel, and addressable, allowing arbitrary sets of independent logical operators of the same Pauli type to be measured in a single round of syndrome extraction. We
benchmark lifted surgery under
circuit-level depolarising noise and, for the $[[ 90, 8, 10 ]]$ code, find logical performance comparable to standard code surgery while requiring ten times fewer rounds of syndrome measurement. By combining speed and parallelism, lifted surgery offers a practical route towards low-overhead fault-tolerant
quantum computing.
Read the full abstract ▾
Quantum Physics
Lorenzo Capra, Lucio de Simone and Roberto Franzosi
Entanglement Distance (ED) was originally proposed as a
geometric measure of
entanglement derived from the Fubini-Study metric on the projective
Hilbert space. Independently, the Meyer-Wallach and Scott measures quantify multipartite
entanglement via linear
entropy. In this work, we demonstrate that these two seemingly distinct frameworks are mathematically identical for pure states of arbitrary finite dimensions. We prove that ED arises naturally as the trace of the Fubini-Study metric tensor over the local subalgebra of observables. Crucially, this
geometric unification yields a direct operational interpretation: the global
entanglement of a pure state is exactly proportional to the total
Quantum Fisher Information (QFI) available for local
unitary estimation. This bridges abstract information geometry with
quantum metrology, demonstrating that ED dynamically quantifies resourcefulness for distributed
quantum sensing, identifying Heisenberg-limited sensitivity in regimes where standard variance-based witnesses fail.
Read the full abstract ▾
Nuclear Theory
Nuclear-physics-guided Gaussian Processes
Javier Rozalén Sarmiento, Hristijan Kochankovski, Arnau Rios et al. (+1 more)
Gaussian Process Regression is a powerful nonparametric
Bayesian method that provides both predictions and principled uncertainty estimates in closed form. The majority of past applications have relied on agnostic priors, but physics knowledge can be systematically encoded into Gaussian Processes through physically-motivated mean functions and kernels. We exploit this capability in the context of
nuclear physics, applying physics-guided Gaussian Process Regression to three problems: nucleon-nucleon scattering phase shifts, mass excesses, and the finite-temperature equation of state of dense matter. In each case, we demonstrate that encoding known theoretical structures yields substantial and systematic improvements in interpolation accuracy, uncertainty calibration, and extrapolation reliability over agnostic baselines. Our results highlight that the design of the prior, and in particular the mean function, is key for obtaining a reliable and well-calibrated Gaussian Process Regression.
Read the full abstract ▾
All authors Javier Rozalén Sarmiento, Hristijan Kochankovski, Arnau Rios, Àngels Ramos
Mesoscale and Nanoscale Physics
Interplay of Kekulé order, flat bands and electron-phonon coupling in graphene
Dominik Szczȩśniak
The Kekulé order in
graphene is known to coexist with both an extended flat band near the van Hove singularity (VHS) and enhanced electron-
phonon coupling. However, the microscopic origin of this interplay is still not fully understood. Here, this behavior is traced to the Kekulé-induced bond distortion and the resulting redistribution of electronic delocalization. In this picture, the conduction band below the VHS is observed to flatten with increasing Kekulé order, extending its intrinsically weakly dispersive region around the saddle point over a broader momentum range. In parallel, the VHS and dimensionless electron-
phonon coupling exhibit approximately quadratic upward responses. The resulting enhancement of the electron-
phonon coupling is found to be predominantly governed by the increasing density of states, with the effective deformation potential remaining weakly affected by the distortion. As such, the obtained results are consistent with previous theoretical and experimental studies, while also pointing toward the narrowing of the conduction band and a possible departure of the electron-
phonon coupling from the conventional adiabatic regime. Altogether, they highlight the potential of controlled Kekulé ordering for engineering emergent correlated
quantum phases in
graphene.
Read the full abstract ▾
Soft Condensed Matter
Impact waves in soft bilayer tissues
Zhenwei Liu, Yang Liu, Michel Destrade et al. (+1 more)
In this study, we investigate impact-wave propagation in a pre-stressed compressible hyperelastic
bilayer resting on a frictionless rigid substrate within the framework of nonlinear elasticity. Semi-analytical solutions for the transient displacement fields induced by localized surface impulses are derived using the
Fourier-Laplace transform, and their long-time asymptotic behavior is obtained through the method of stationary phase. Finite element simulations are further performed to validate the theoretical predictions. The results establish a direct connection between characteristic features of the transient displacement fields and the group velocities of the guided-wave modes, revealing how dispersive propagation and modal contributions shape the observed waveforms. Three representative
bilayer models corresponding to human articular cartilage, gingiva, and skin are then considered to examine the effects of variations in layer stiffness and thickness. The results show that structural and material variations can substantially modify the spatial distribution, arrival positions, and characteristic velocities of impact waves. In particular, higher-order modes can make significant contributions to the displacement response in certain parameter regimes, such that the dominant features of the wavefield cannot always be characterized by the fundamental mode alone. These findings demonstrate that transient-wave measurements contain mechanical information beyond that captured by a single characteristic surface-wave velocity and provide a theoretical basis for interpreting transient wavefields in multilayered soft materials and for future non-invasive mechanical characterization.
Read the full abstract ▾
All authors Zhenwei Liu, Yang Liu, Michel Destrade, Yue-Sheng Wang
High Energy Physics (Phenomenology)
NLO corrections to the NEik DIS structure functions
Tolga Altinoluk, Guillaume Beuf, Jules Favrel et al. (+1 more)
We summarize the next-to-leading order (NLO) corrections to next-to-eikonal (NEik)
quark background contributions to DIS structure functions. At NEik accuracy, in addition to corrections arising from the
gluon background field of the target, DIS structure functions receive contributions from the $t$-channel
quark exchanges, represented by insertions of the
quark background field of the target. The latter provide the lowest order contributions in $\alpha_s$ at NEik accuracy. We show that the NLO corrections to the longitudinal NEik structure functions are finite, whereas those to the transverse NEik structure functions exhibit rapidity and ultraviolet (UV) divergences. We analyze these divergences and extract the finite contributions.
Read the full abstract ▾
All authors Tolga Altinoluk, Guillaume Beuf, Jules Favrel, Michael Fucilla
Computational Physics
Stress-Testing Dynamical and Generative Downscaling Using Subseasonal Extreme Precipitation Forecasts
Mauricio Lima, Marika Koukoula, Romain Pilon et al. (+4 more)
Coarse spatial resolution limits the ability of subseasonal prediction models to resolve extreme precipitation. Downscaling with either dynamical or deep generative models can overcome this issue, but the comparative performance of these models for extremes across different atmospheric regimes remains poorly understood. In this work, we evaluate the Weather Research and
Forecasting (WRF) model against a
diffusion-based generative model by downscaling two physically distinct, extreme precipitation events up to lead times of 3 weeks. For a fair comparison with WRF, which can downscale boundary conditions from different driving models without model-specific training, the
diffusion model is trained in an unpaired fashion. Both approaches improve upon the raw European Centre for Medium-Range Weather Forecasts forecasts, in comparison to fused rain gauge-radar observations in Switzerland (CombiPrecip), but exhibit regime-dependent strengths. WRF achieves the highest probabilistic skill for a multicell, non-stationary event. Conversely, the
diffusion model is more consistent across different performance metrics for the two events, outperforming WRF in a more stationary supercell event. These results demonstrate that explicit dynamical modeling can add value for specific precipitation events for subseasonal lead times, and that generative downscaling adds value more broadly in different situations.
Read the full abstract ▾
All authors Mauricio Lima, Marika Koukoula, Romain Pilon, Monika Feldmann, Erwan Koch, Daniela I.V. Domeisen, Tom Beucler
High Energy Physics (Phenomenology)
Hunting the Unseen: Deep Learning Analysis for Semi-Visible Jet Tagging
Miguel A. Avendaño-Bernal, Srinandan Dasmahapatra, Ahmed Hammad et al. (+4 more)
Semi-Visible Jets (SVJs) constitute a distinctive
collider signature of strongly interacting dark sectors,
embedding Dark Matter candidates, wherein jets contain both visible Standard Model objects and invisible dark
hadrons, giving rise to correlated jet activity and missing transverse momentum. In this work, we investigate SVJs produced through a heavy Z' mediator and perform an study over a representative set of
benchmark scenarios spanning different mediator masses and dark sector parameters in the context of so-called Hidden Valley Models. To characterise the signal, we combine global event kinematics with jet substructure observables, including the primary Lund Jet Plane (LJP), the two-point energy correlation, angularity, and charged
hadron multiplicity. These representations are used to train five Deep Learning classifiers for SVJ vs standard jet discrimination: a
Vision Transformer operating on LJP images, a JetLOV network based on a hierarchical clustering tree, a Multi-Layer Perceptron using high level observables, and two
multimodal networks that combine the image-based or hierarchical representations of the radiation pattern with the high jet-level observables. This enables a direct combination of global kinematics, radiation patterns, and jet clustering structure. We find that global kinematic observables outperform the LJP and hierarchical jet representations, with the latter providing stronger discrimination than LJP images. Combining these complementary representations with global kinematics yields the best overall performance. More broadly, this study shows that unlocking the full discovery potential of SVJs would benefit from going beyond global kinematics to exploit the rich information encoded in their internal structure, providing a
benchmark for future searches at the Large
Hadron Collider.
Read the full abstract ▾
All authors Miguel A. Avendaño-Bernal, Srinandan Dasmahapatra, Ahmed Hammad, Stefano Moretti, Mihoko Nojiri, Michael H. Seymour, Claire Shepherd-Themistocleous
Superconductivity
Out-of-equilibrium relaxation dynamics of the superconducting order parameter in CsV$_3$Sb$_5$
Avi Shragai, Alexander Won, Jonathan M. DeStefano et al. (+4 more)
The application of a time-varying strain field drives a superconducting order parameter out of
equilibrium. How the order parameter relaxes back to
equilibrium depends both on the structure of the superconducting gap and on the nature of quasiparticle scattering. We report the discovery of an ultrasonic attenuation peak inside the superconducting state of the kagome
superconductor CsV$_3$Sb$_5$. This peak is the natural consequence of the order parameter relaxation time matching the ultrasonic drive frequency near $T_{\rm c}$. From the measured frequency dependence of the peak, we extract a microscopic scattering time of $\tau_N = 25$ ps. This timescale is two orders of magnitude longer than the elastic scattering time as determined by resistivity measurements, but is comparable to the inelastic scattering time determined by thermal transport. Within the conventional framework of order-parameter relaxation, this implies that elastic scattering is ineffective at relaxing the superconducting condensate, consistent with a sign-preserving $s$-wave state obeying Anderson's
theorem.
Read the full abstract ▾
All authors Avi Shragai, Alexander Won, Jonathan M. DeStefano, Andrea Capa Salinas, Ganesh Pokharel, Stephen D. Wilson, B. J. Ramshaw
Mesoscale and Nanoscale Physics
Bridging steady-state and time-domain descriptions of molecular electron transport
Thibaut Lacroix, Namgee Cho, Clemens Vittmann et al. (+3 more)
Electron transmission from an input electrode, through a molecular system, to an output electrode has been widely studied using the steady-state non-
equilibrium Green's function (NEGF) method. Recently, the wave packet method, which provides access to the transient dynamics of electrons as well as internal molecular degrees of freedom, has been employed to investigate enantiospecific electron transport through
chiral molecules. In this work, we derive the quantitative relation between the transmission of a finite-size wave packet and the energy-resolved NEGF transmission, showing that the former corresponds to a spectral average of the latter weighted by the wave packet energy distribution. Exploiting this correspondence, we construct non-Gaussian auxiliary wave packets whose spectral weight encodes the Landauer energy-window, allowing current-voltage characteristics to be obtained directly from time propagation. We further show that the correspondence extends to
spin-resolved transport in a
spin-
phonon model of chirality-induced
spin selectivity.
Read the full abstract ▾
All authors Thibaut Lacroix, Namgee Cho, Clemens Vittmann, James Lim, Susana F. Huelga, Martin B. Plenio
Instrumentation and Methods for Astrophysics
Bayesian Superiority in On/Off analysis
Gleb Babenov and Petr Satunin
We present a detailed comparison of
Bayesian criteria with three non-informative priors - flat, Jeffreys, and scale-invariant - for testing a signal against an unknown background and compare them with the classical frequentist Li-Ma approach in the On/Off problem. We perform Monte Carlo simulations for various background levels and evaluate the Li-Ma and
Bayesian criteria by their Type I error rates. We then simulate a nonzero signal and compare the criteria in terms of Type II error rates. We find that both the Li-Ma criterion and the
Bayesian criterion with the Jeffreys prior control Type I error well, excluding the case of small background $b < 0.5$; the
Bayesian criterion with the Jeffreys prior is statistically more powerful than the Li-Ma criterion for $b \lesssim 40$.
Read the full abstract ▾
High Energy Physics (Phenomenology)
An event generator for $h\to b\bar{b}$ decays at NLO in SMEFT matched to a parton shower
Livia E. G. Maskos, Benjamin D. Pecjak, Shakeel Ur Rahaman et al. (+1 more)
We present a Sherpa implementation of NLO corrections in dimension-six Standard Model Effective Field Theory (SMEFT) to the
benchmark process $h\to b\bar b$. The calculation includes NLO QCD corrections matched to a parton shower using an MCatNLO-type framework for decays. Virtual weak effects are included as two-body
matrix-element corrections in different electroweak input schemes, with the corresponding decay events also evolved with the QCD parton shower. We present numerical results for the inclusive decay rate and for differential distributions in the
Higgs-
boson rest frame, and illustrate how the decay implementation can be combined with an independently generated production sample by
embedding it in associated $Zh$ production at the LHC. This proof-of-principle implementation demonstrates how NLO SMEFT corrections can be incorporated into the widely used Sherpa event generator, providing a basis for extensions to other processes and for SMEFT studies with realistic final states and fiducial cuts within that framework.
Read the full abstract ▾
All authors Livia E. G. Maskos, Benjamin D. Pecjak, Shakeel Ur Rahaman, Marek Schönherr
Strongly Correlated Electrons
Acoustic Wave-Function Imaging of Sublattice Physics in a Kagome Lattice
L. Müller, N. Endres, B. Geldiyev et al. (+4 more)
The canonical kagome band structure hosts a Dirac cone, saddle-point van Hove singularities (vHS), and a flat band. Characteristically, these features exhibit distinct sublattice localization within the three-site basis of the kagome
lattice. However, experimental proof of this sublattice character is challenging and requires direct access to both the real-space wave function and its associated momentum-space texture. Here, we implement an acoustic kagome
lattice on the cm scale and measure the full excitation spectrum, thereby imaging the wave function at each
lattice site, including both amplitude and phase. This enables investigation of the momentum-dependent sublattice texture across the complete band structure, particularly at the flat band and at the mixed- and pure-sublattice van Hove singularities. Our results are in excellent agreement with minimal tight-binding model calculations and constitutes the first direct experimental observation of the sublattice-resolved band structure in a kagome
lattice.
Read the full abstract ▾
All authors L. Müller, N. Endres, B. Geldiyev, S. Widmann, K. Burkard, M. Ünzelmann, F. Reinert
Instrumentation and Methods for Astrophysics
The Balloon-borne VLBI Experiment (BVEX) Radio Telescope and Position Tracking System
Felix M. Thiel, Mayukh Bagchi, Laura M. Fissel et al. (+17 more)
Very Long Baseline Interferometry (VLBI) is a technique in
radio astronomy that vastly increases the diffraction limited angular resolution of
radio observations by correlating simultaneous observations of
radio telescopes separated by thousands of kilometers. Ground-based high-frequency VLBI is limited in baseline length by the diameter of the Earth and in sensitivity by molecular absorption of the Earth's atmosphere. One of the ways to improve VLBI is with balloon
telescopes, which are much cheaper than space VLBI
telescopes. In addition balloon-VLBI stations could also improve image quality due to increased uv-coverage. As a first step to achieving VLBI from a balloon-borne platform we present the Balloon-borne VLBI Experiment (BVEX). This is a novel, first-generation balloon-borne VLBI station observing at K-band (22 GHz) which launched as part of the Canadian Space Agency (CSA) STRATOS campaign from Timmins, Ontario, Canada in August 2025, with the aim to demonstrate VLBI from a balloon-borne platform by correlating with a large ground based
telescope. We discuss the design of the 36 inch (91 cm)
radio telescope and receiver with a 2 GHz bandwidth built from commercial-off-the-shelf (COTS) components as well as the
telescope pointing system capable of interfacing with the CSA's CARMENCITA gondola. We also present a novel high precision position tracking system built from COTS components giving <1 mm precision on 1 s time scales which is required for achieving phase tracking at 22 GHz. We further show on-the-ground testing results from the 2025 Timmins campaign. The 2025 flight from Timmins was not successful due to a leak in the balloon preventing the payload from reaching its target altitude where accurate gondola pointing is possible. We therefore wrap up by presenting plans to upgrade the
telescope for a potential next flight opportunity from Palmas, Tocantins, Brazil in 2027.
Read the full abstract ▾
All authors Felix M. Thiel, Mayukh Bagchi, Laura M. Fissel, Aarchi Shah, Lindy Blackburn, Emily Butler, Rafael Costa, Thomas Emo, Vincent L. Fish, Daryl Haggard, Michael D. Johnson, Jessica Lo, Maggie Oxford, Dominic W. Pesce, Ganesh Rajagopalan, Javier L. Romualdez, Adrian K. Sinclair, Bonnie Slocombe, Stephanie St-Jean, Terry Yang
Strongly Correlated Electrons
Certified reduced-basis emulation of conformal field theories on the fuzzy sphere
Virgil V. Baran
Fuzzy-sphere regularization gives numerical access to three-dimensional conformal field theories (CFTs), but locating one requires testing for criticality across the parameter space of microscopic couplings. We reduce the search cost by about two orders of magnitude, combining an exact diagonalization based on states having definite total angular momentum with a certified reduced-basis emulator that reconstructs energies, observables and their derivatives continuously across the couplings from a handful of exact solutions per system size. The combination reproduces the published ground-state-energy analysis of the fuzzy-sphere Ising model and the published conformal data of a three-
flavor fuzzy-sphere realization of the O(2) Wilson–Fisher CFT, including quantities defined by parameter derivatives. Applied to the O(2) model with no CFT input, the ground-state-energy criterion locates the critical coupling to within half a percent of a density
matrix renormalization group value obtained on systems more than twice the size, and maps the critical line of the model across the coupling plane. Ground-state criteria locate the critical line robustly, but the point they select along it is weakly determined, and the computed dimensions come closest to the bootstrap elsewhere along the line.
Read the full abstract ▾
Quantum Physics
Nonlinear dynamics and mechanical frequency combs with a Meissner-levitated micromagnet
Yiqi Wang, Trisha Madhavan, Vanessa Wachter et al. (+6 more)
Nonlinearities in multimode mechanical systems can give rise to rich dynamical phenomena with great potential for sensing applications and for future
quantum experiments. We demonstrate that the coupled center-of-mass and rotational motion of a Meissner-levitated micromagnet offer a promising platform for nonlinear dynamics, combining low dissipation,
magnetic tunability, strong intrinsic Duffing nonlinearities, and nonlinear intermodal couplings. We use this tunability to demonstrate the generation of a mechanical frequency comb in the micromagnet dynamics, realized by parametric excitation of two translational modes followed by cascaded nonlinear frequency mixing, which produces a phononic comb with tunable spacing. At large amplitudes, nonlinear coupling to a low-frequency librational mode of the magnet leads to parametric excitation and phase locking of that mode, generating a dense spectral fine structure at subharmonics of the drive. These results establish levitated micromagnets as a platform for nonlinear multimode mechanics, with potential applications in precision sensing and
quantum-limited metrology.
Read the full abstract ▾
All authors Yiqi Wang, Trisha Madhavan, Vanessa Wachter, J. DaLi Schaefer, Addison NewRingeisen, Zhiyuan Wei, Frankie Fung, Benjamin A. Stickler, Mikhail D. Lukin
Materials Science
Competition between vacancy creation and filling in defect-engineering of hBN
Shrirang Chokappa, Manuel Längle, Barbara Maria Mayer et al. (+13 more)
Hexagonal boron nitride (hBN) has recently become the focus of intense research as a material that can host
quantum emitters. It is known that such emission is related to point defects, but in order to conclusively correlate specific defects to their spectra, having control over the defect creation mechanism is required. Here, we prepare freestanding, monolayer hBN samples and irradiate them with ultra-low-energy (150 eV) Ar+ ions. The samples are characterized before and after irradiation via scanning transmission electron microscopy to assess the defect density and distribution. Contrary to what analytical potential molecular dynamics simulations have predicted, we predominantly observe boron single vacancies after ion irradiation, followed by double vacancies at half the count. Moreover, we also observe that vacancy filling with Si and C
impurity atoms plays a more significant role in the created defects than previously assumed, potentially posing a problem for selective creation of
quantum emitters in hBN.
Read the full abstract ▾
All authors Shrirang Chokappa, Manuel Längle, Barbara Maria Mayer, Vladimir Zobač, Jacob Madsen, Diana Propst, David Lamprecht, Philipp Irschik, Arixin Bo, Clara Kofler, Vinzent Hana, Fabian Kraft, Clemens Mangler, Lado Filipovic, Toma Susi, Jani Kotakoski