Physics Education
The Force Concept Inventory Across Continents: Testing Q-Matrix Transferability and Cross-Cultural Differences in Mechanics Reasoning
Wade Naylor, Raheeq Tahir, Alan S. Cornell et al. (+1 more)
The Force Concept Inventory (FCI) is one of the most widely used research-based assessments in physics education, yet the assumption that its underlying cognitive structure is transferable across educational contexts remains largely untested. This study investigates the transferability of FCI Q-
matrices using the Generalized Deterministic Inputs, Noisy "And" Gate (G-DINA) cognitive diagnostic applied to two large cohorts: students from the Learning About STEM Student Outcomes (LASSO) online system database in the United States (N = 4,750) and introductory physics students at the University of Johannesburg, South Africa (N = 1,016). Rather than treating the analysis as a local model calibration exercise, we frame the problem as one of cross-context cognitive invariance. Differential Item Functioning (DIF) analyses revealed substantial cross-cultural differences, with 14 of 30 items exhibiting high DIF after controlling for latent skill mastery. These differences were concentrated in force dynamics and contact-force
reasoning and remained invariant under alternative Q-
matrix specifications. The findings suggest that observed differences reflect genuine variations in students' conceptual
reasoning rather than psychometric artifacts, highlighting the importance of validating Q-
matrix structures before deploying cognitive diagnostic and adaptive assessments across diverse non-local educational settings.
Read the full abstract ▾
All authors Wade Naylor, Raheeq Tahir, Alan S. Cornell, Xuelan Qiu
Soft Condensed Matter
Decoupling support-dependent transport profiles from molecular water motion
Jannik Mehlis and Matthias Wessling
Pressure and concentration profiles from non-
equilibrium molecular dynamics (NEMD) simulations are often used to infer water transport mechanisms in dense and swollen
polymer membranes. However, the mechanical restraints needed to stabilize simulated membranes can alter these profiles and their interpretation. Here, we test whether restraint-induced differences in pressure and water concentration profiles are accompanied by changes in molecular water dynamics. Crosslinked poly(ethylene glycol) diacrylate (PEGDA) membranes were simulated using three support strategies: a
graphene support
lattice, frozen membrane atoms near the permeate interface, and homogeneously distributed frozen membrane atoms. The restraints produced markedly different profiles, ranging from solution-
diffusion-like to pore-flow-like, while overall water fluxes remained comparable. Molecular water dynamics, however, changed little. Interfacial exchange was strongly bidirectional and far exceeded the net permeation flux, membrane water diffusivities were similar, and complete crossings occurred in both directions. Local water associations were short-lived, and directional velocity correlations decayed rapidly with time and distance. Thus, substantially different pressure and concentration profiles can arise despite similar molecular water dynamics. Such profiles alone are therefore insufficient to identify transport mechanisms in mechanically restrained NEMD simulations. In PEGDA, water motion is dominated by
stochastic diffusion with a small net directional bias.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Probing Inflationary Origins of Primordial Black Holes with LIGO–Virgo–KAGRA O1–O4a data
Haipeng An, Huai-Ke Guo, Mai Qiao et al. (+3 more)
Large
primordial curvature perturbations not only produce
primordial black holes (PBHs) but also inevitably source a scalar-induced
stochastic gravitational-wave background upon horizon reentry. We analyze the combined LIGO–Virgo–KAGRA O1–O4a data to constrain two representative inflationary mechanisms for generating such perturbations: ultra-slow-roll inflation and an inflationary phase transition. Detecting no evidence for either scenario, we place 95% credible upper limits on the
curvature-spectrum amplitude across the frequency range accessible to ground-based interferometers. Translated into the PBH context, these limits already exceed conventional constraints, probing abundance fractions far below unity. Our results remain robust even when the PBHs themselves are too rare to be directly detected or have evaporated. This work demonstrates that
stochastic gravitational-wave observations offer a powerful and complementary probe of small-scale inflationary physics and PBH formation, with upcoming interferometers promising to extend sensitivity to a wider range of inflationary epochs and PBH masses.
Read the full abstract ▾
All authors Haipeng An, Huai-Ke Guo, Mai Qiao, Lian-Tao Wang, Chen Yang, Yue Zhao
Statistical Mechanics
Slow activity decay in excitable models with discontinuous phase transitions
Paulo H. Lorenzoni, Géza Ódor, Silvio C. Ferreira et al. (+1 more)
As a simple model of interacting systems of excitable degrees of freedom, we consider a threshold contact process on various
lattices and networks, in which a successful activation event requires the presence of more than one active neighbors. We show by combining numerical simulations and a phenomenological theory that, in the two-phase coexistence region and for a sufficiently low initial activity, a slower-than-exponential temporal decay of the global density emerges, caused by the spontaneous formation of slowly vanishing and non-communicating clusters of activity. This slow-decay phenomenon is found to appear generally for regular
lattices and also for finite-dimensional random
lattices such as the Voronoi-Delaunay network. However, the slow-decay is impeded by small-world property, as demonstrated by simulations on random-regular networks. In the case of a power-law decay of the order parameter, which is valid among others on two-dimensional regular
lattices, our phenomenological theory points out that the decaying state is stable against unbounded nucleation only if the decay exponent exceeds $1/2$. Besides the well-known Griffiths effects of quenched random systems, this slow-decay phenomenon rooted in the threshold condition provides an alternative mechanism of off-critical but scale-free dynamics, occurring also in the absence of disorder.
Read the full abstract ▾
All authors Paulo H. Lorenzoni, Géza Ódor, Silvio C. Ferreira, Róbert Juhász
Accelerator Physics
Damping Ring Optimization in Natural Emittance and IBS Dominated Regimes
Matthew Andorf, Nigel Lockyer, Emilio Nanni et al. (+2 more)
Linear electron-positron
colliders enable precision measurements of Standard Model observables and beyond. Modern linear
colliders need damping rings wherein the emittance of the source is damped and asymmetrized. A previous work [Phys. Rev. ST Accel. Beams 4, 021001 (2001)] delineated a systematic procedure for damping ring design. In this paper, we apply those principles, and frame damping ring design as a constrained numerical minimization problem when including intrabeam scattering. We use a multi-objective genetic optimization to map the transition from natural- emittance-dominated to intrabeam-scattering-dominated regimes. We compare to analytic results where possible to good agreement. The analysis is applied to parameters for the C$^{3}$
collider concept, but the procedure is fully generalizable to other linac parameters.
Read the full abstract ▾
All authors Matthew Andorf, Nigel Lockyer, Emilio Nanni, Caterina Vernieri, Jared Maxson
Optics
Compact, open, and tunable two-dimensional Fabry-Pérot cavity
Bruno Bender, Andrea Bergschneider, Marcel Baer et al. (+2 more)
In order to enhance light-matter interactions, optically active material, like a
semiconductor, can be embedded into an optical cavity. For small cavity mode volumes, which are required for reaching the strong coupling regime, this is typically done by fabrication of microcavities. While guaranteeing a mechanically stable cavity, these systems lack tunability and are difficult to implement for small samples like van der Waals
heterostructures (vdW). Here we present a design for a fully tunable two-dimensional (2D) Fabry-Pérot (FP) cavity which can host any material. The cavity can be freely positioned between two confocal high-NA aspheric lenses which allows for optical transmission microscopy and spectroscopy in real and momentum space. In order to maintain maximal mechanical stability, the cavity mirrors are held in a monolithic titanium frame. A pre-loaded flexure joint allows for manual coarse tuning of the cavity length and mirror parallelism, while three piezo actuators in a tripod layout can be used for fine tuning. We find cavity length fluctuations smaller than 100 pm, measure a finesse of 360 and reach the lowest accessible $m=3$ cavity mode (one electric field antinode within the air gap) at a minimal physical mirror separation of 380 nm. In order to demonstrate the 2D nature of the cavity mode we perform momentum space imaging in transmission as well as spectroscopy to measure the cavity dispersion.
Read the full abstract ▾
All authors Bruno Bender, Andrea Bergschneider, Marcel Baer, Martin Kroner, Wolf Wüster
Quantum Physics
Optimal Hamiltonian Parameter Estimation in the Presence of Nuisance Parameters
Zhiyao Hu, Haidong Yuan, Liang Jiang et al. (+1 more)
In many sensing applications, the quantity of interest is not the only unknown, there are also additional unknown parameters, known as nuisance parameters, that affect the precision of estimation. While the ultimate local precision limit for a target parameter is well understood in the absence of nuisance parameters, the problem becomes significantly more challenging when they are present. In this work, we develop a framework for optimal
Hamiltonian parameter estimation in the presence of nuisance parameters. We introduce an effective generator that captures the influence of nuisance parameters on the target precision, providing an explicit characterization of the ultimate precision limit for estimating the target parameter. Finally, we provide explicit optimal protocols, including probe state, control, and measurement that saturate this fundamental limit.
Read the full abstract ▾
All authors Zhiyao Hu, Haidong Yuan, Liang Jiang, Zain H. Saleem
Strongly Correlated Electrons
Chiral Valence-Bond Solid and Chiral Triplons
Shinnosuke Koyama and Kazumasa Hattori
We propose a
chiral valence-bond solid (VBS) in which
spin-singlet bond order itself spontaneously acquires handedness without
magnetic order. Using a
spin-
lattice model on the diamond
lattice, we demonstrate two enantiomorphic VBS states. In the presence of anisotropic
spin interactions, this emergent handedness is inherited by
chiral triplons with
spin-split bands and
spin textures that reverse between the two enantiomers. These textures generate a temperature-gradient-induced net
spin response whose sign is set by the VBS handedness. The imaginary off-diagonal components of the dynamical
spin structure factor encode the triplon polarization and change sign between the two enantiomers, enabling direct detection of
chiral triplons and the selected handedness by polarized inelastic
neutron scattering. Our results establish a direct connection between spontaneous chirality and
magnetic excitations, opening avenues for exploring the interplay between
quantum magnetism and
chiral physics.
Read the full abstract ▾
Mathematical Physics · Cross-listed from math.AG
Spectrum of singularities, analytic torsion and Calabi–Yau degenerations
Dennis Eriksson and Gerard Freixas i Montplet
We relate the spectrum of singularities to the geometry of degenerating Calabi–Yau
manifolds through holomorphic analytic torsion. We express the leading asymptotic coefficients of the analytic torsion of holomorphic differential forms in terms of Hodge-theoretic invariants of vanishing cycles. For isolated hypersurface singularities, these formulas lead to the formulation of new higher Durfee–Saito
conjectures bounding Hodge-filtration dimensions by the Milnor number and Eulerian numbers. We also prove that, for isolated quasi-homogeneous singularities, the spectral measure is dominated in convex order by the corresponding Irwin–
Hall distribution. Applying the torsion formulas to the BCOV invariant yields a computable obstruction to birational smooth fillings. For isolated singularities, its local contribution is expressed in terms of Hertling's spectral variance and a Bernoulli sum determined by monodromy. As applications, we rule out birational smooth fillings for projective Calabi–Yau degenerations with smooth total space and singular central fiber having only ADE or terminal Brieskorn–Pham singularities, in relative dimension at least three, extending results of Voisin.
Read the full abstract ▾
Strongly Correlated Electrons
Diversifying time evolution of matrix product states using BUGs
Kornél Kapás, Dominik Sulz, Charlotte Verhoeven et al. (+3 more)
Time
evolution of tensor-network states is a central tool for studying nonequilibrium dynamics in strongly correlated
quantum systems. In the past decade, using the time-dependent variational principle (TDVP) discretized by projector-splitting has become the gold standard for evolving
matrix product states (MPS) with long-range
Hamiltonians. More recently, a conceptually different class of discretizations of the TDVP, the class of Basis Update and Galerkin (BUG) integrators, has been developed within the framework of dynamical low-rank approximation, offering an alternative, more flexible approach. In this work, we formulate two BUG integrators explicitly for MPS. The BUG integrators result in "single-site" MPS integrators that are robust with respect to small singular values, avoid backward-in-time substeps, and naturally allow for the adaptive choice of bond dimensions. We consider the augmented BUG integrator of first order and the midpoint BUG integrator of second order and clarify their relation to the projector-splitting discretization of the TDVP. Using representative models of strongly correlated
quantum systems, like the XY
spin model with long-range interaction and two-dimensional
lattice models of
fermions and
spins of various lengths, we perform a systematic numerical comparison between BUG and projector-splitting time discretizations of the continuous-time TDVP, focusing on scalability, numerical complexity, and accuracy. We find that BUG integrators, due to their reduced numerical cost and the flexibility of the concept, provide a competitive and, in certain regimes, advantageous alternative to the well-established time-stepping by projector-splitting in TDVP, especially in models with large local dimensions, and in cases where observables are extracted with high temporal resolution.
Read the full abstract ▾
All authors Kornél Kapás, Dominik Sulz, Charlotte Verhoeven, Miklós Antal Werner, Örs Legeza, Christian Lubich
Quantum Physics
State-adapted generalized mean-field projections for Pauli propagation of Heisenberg dynamics
Federico Tomás B. Pérez, Gabriela Wójtowicz and Martin B. Plenio
The Heisenberg picture can make
quantum many-body simulation efficient when evolved observables admit compact operator representation within low-dimensional structures. Conventional Pauli-string propagation and truncation techniques exploit this structure, but in coherent
Hamiltonian dynamics their error control is often heuristic and their stability can be poor. We introduce a state-adapted Krylov framework based on
geometric generalized mean-field projections of many-body observables onto low-body operator subspaces. The resulting dynamics approximate expectation values, do not extend spatial support beyond that prescribed by Lieb-Robinson bounds, and compress high-body correlations onto their state-relevant low-body representatives rather than simply discarding them. We derive necessary operator-
entanglement obstructions to low-body representation and conditional sufficient bounds on representation and dynamical errors involving nonstabilizerness and controlled high-body tails. Numerical
benchmarks show improved, stable finite-$m$ hierarchies and simulations on large three-dimensional
lattices, establishing a scalable state-adapted alternative to conventional Heisenberg-picture weight-truncation of Pauli strings.
Read the full abstract ▾
Materials Science
Ultrastrong Au-Te bonding drives disorder in monolayer ZrTe$_5$ on gold
Konrád Kandrai, Zoltán Tajkov, Péter Kun et al. (+3 more)
Monolayer ZrTe$_5$ is predicted to host a large-gap
quantum spin Hall phase, motivating efforts to isolate single layers of the material. Gold-assisted exfoliation produces clean monolayers of many chalcogen-terminated van der Waals
crystals, but the strong Te-Au bond may compete with the bonding network of the ZrTe$_5$ layer itself. Across tens of samples, low-temperature scanning tunneling microscopy on gold-exfoliated flakes shows a disordered monolayer surface in the overwhelming majority of cases, while thicker flakes preserve the characteristic quasi-one-dimensional chain structure. Ab initio calculations of the ZrTe$_5$/Au(111) interface reproduce this asymmetry and resolve its mechanism: the Te atoms facing the gold chemisorb, rupturing the weak zigzag Te-Te bonds that cross-link the ZrTe$_3$ chains, turning the discrete bond-length spectrum of the
crystal into a continuous one, while the chains persist as distorted units. Charge analysis shows the signature of covalent Te-Au bonding with a modest transfer that hole-dopes the monolayer; in the
bilayer, the distortion and the doping stay confined to the layer contacting the gold, and the chemisorption and disorder each preclude the predicted
quantum spin Hall phase. The same quasi-covalent Te-Au bond may perturb the contact layer of other gold-exfoliated Te-terminated
crystals, particularly those with weakly connected intralayer networks.
Read the full abstract ▾
All authors Konrád Kandrai, Zoltán Tajkov, Péter Kun, Levente Tapasztó, János Koltai, Péter Nemes-Incze
Quantum Physics
Fast quantum squeezing of a nanomechanical oscillator with an inverted potential
Oscar Schmitt Kremer, Lorenzo Dania, Lukas Novotny et al. (+1 more)
Nonclassical states of nano- and micro-mechanical motion enable measurements beyond the standard
quantum limit and constitute a key resource for
quantum sensing and metrology. The most strongly squeezed mechanical states to date have been generated with electromechanical platforms under cryogenic refrigeration and using reservoir engineering. To push mechanical systems deeper into the
quantum-squeezed regime requires protocols that increase the rate at which squeezing is generated to more strongly overcome the decoherence rate at which state purity is lost. Here, we squeeze the 800 kHz libration mode of a silica nanoparticle optically levitated in
vacuum at room temperature. We expose our mechanical oscillator to an optically generated inverted potential, where the squeezing operation proceeds at an exponentially accelerated rate. We reach a squeezed quadrature variance 11 dB below the
vacuum fluctuations within 250 ns. Our protocol establishes a new paradigm for generating
quantum squeezing of mechanical motion and offers a platform for
quantum-enhanced sensing with massive oscillators.
Read the full abstract ▾
All authors Oscar Schmitt Kremer, Lorenzo Dania, Lukas Novotny, Martin Frimmer
Mesoscale and Nanoscale Physics
Superfluorescence in CdS/CdSe/CdS Spherical Quantum Wells Modulated by Excitation Geometry
Chunzheng Bai, Qihao Sun, Yiying Zhu et al. (+6 more)
Superfluorescence (SF) originates from the spontaneous buildup of macroscopic coherence among initially incoherent emitters. Its formation is highly sensitive to dephasing and collective coupling in the system. Here, we observe room-temperature SF in CdS/CdSe/CdS spherical
quantum wells. With increasing excitation fluence, the peak emission intensity shows a nearly quadratic increase, while the emission delay and pulse width decrease. Burnham-Chiao ringing is also observed, revealing the characteristic collective radiation dynamics of SF. Further experiments with stripe excitation show that shortening the excitation length L changes the dominant fast emission from amplified spontaneous emission to SF. More importantly, the threshold for SF under stripe excitation is only about 1/30 of that under spot excitation. This large reduction indicates that the propagating radiation field provided by spatially extended excitation favors the buildup of cooperative coherence. These findings provide direct experimental evidence for understanding ultrafast many-body coherence dynamics and offer a route to actively control collective emission at room temperature.
Read the full abstract ▾
All authors Chunzheng Bai, Qihao Sun, Yiying Zhu, Ruilin Xu, Bin Gu, Jinsong Qi, Fengrui Hu, Xiaoyong Wang, Jiayu Zhang
General Relativity and Quantum Cosmology
Nonlinear Degrees of Freedom of Born-Infeld New Massive Gravity
Zeynep Su Koc and Bayram Tekin
Born-Infeld New Massive
Gravity (BINMG) is an all-order
curvature extension of New Massive
Gravity in three dimensions, whose linearized spectrum around its unique maximally symmetric
vacuum contains the two polarizations of a massive
spin-two field. Whether an additional scalar degree of freedom appears in the full nonlinear theory has remained an open question. We perform a nonlinear canonical analysis of BINMG using its auxiliary-metric formulation. On the regular branch connected to the maximally symmetric
vacuum, the Dirac
algorithm yields three first-class diffeomorphism constraints and a second-class pair of scalar constraints. The resulting count gives exactly two local degrees of freedom per spatial point. Thus, nonlinear BINMG propagates no additional Boulware-Deser-type scalar mode on this branch.
Read the full abstract ▾
Fluid Dynamics
Newtonian fluid invasion into a Yield-Stress Fluid-Saturated Medium
Nathan Abitbol, Alex Hansen, Alberto Rosso et al. (+2 more)
We investigate pressure imposed two-phase flows in porous media where a Newtonian fluid displaces an immiscible Bingham yield-stress fluid. Using a pore-network model, we identify invasion patterns governed by three dimensionless parameters: the pressure-based capillary number $Ca_P$, the viscosity ratio $M$ , and a number $R_\tau$, the ratio of yield stress to capillary forces. Beyond the classical Lenormand regimes (viscous fingering, capillary fingering, stable displacement), we discover two new regimes: a tree-like pattern at low viscosity ratios and a progressively widening column-like pattern at high viscosity ratios. We characterize all regime transitions and establish a breakthrough condition for the invading fluid.
Read the full abstract ▾
All authors Nathan Abitbol, Alex Hansen, Alberto Rosso, Federico Lanza, Laurent Talon
High Energy Physics (Phenomenology)
Supernova cooling from neutrinophilic dark matter
Yugen Lin
Core-collapse
supernova serve as a powerful laboratory for testing physics beyond the Standard Model (BSM), particularly regarding new, light states interacting feebly with SM particles. In this work, we investigate for the first time the production of dark matter (DM) via the
neutrino-
neutrino scattering processes inside a core-collapse
supernova, which contributes to the excessive cooling. By incorporating state-of-the-art
supernova simulation data , we derive stringent and robust limits on sub-GeV dark matter with effective couplings to
neutrinos. We find that the existing and projected constraints from indirect detection are quite weak. Our
supernova cooling bounds on DM-
neutrino reference cross section can improve indirect detection limits more than ten orders of magnitude for DM masses below $\mathcal{O}(100)$ MeV, and it can also provide strong complementarity with other cosmological constraints. Our results highlight the exceptional sensitivity of core-collapse
supernova to feebly interacting particles and motivate future
supernova neutrino observations as a powerful probe of light dark sectors.
Read the full abstract ▾
Mathematical Physics · Cross-listed from math.PR
Moments Comparison Inequalities for Critical 2d Stochastic Heat Flow, Polymers and GMC
Ziyang Liu and Zuodi Xie
We employ a Gaussian convex inequality developed in [AC15], [Che26], [Gue22], and [FUMPC26] to establish (one sided) moment comparison inequalities for Gaussian multiplicative chaos, directed
polymers in Gaussian environment and, in particular, the Critical 2d
Stochastic Heat Flow (SHF), including upper bounds on negative moments, as well as similar lower bounds for $p$-th moments with $p\in (0,1)$. For the Critical 2d SHF, averaged over small balls, we also obtain the matching (up to multiplicative constants) complementary bounds. We establish the complementary bounds using a bootstrap argument inspired by [DS10] and a
geometric decomposition introduced in [GT26]. Specifically, we prove that for locally averaged SHF, for every $p\in\mathbb R$, the $p$-th moment is, up to multiplicative constants, bounded in both sides by the $\frac{p(p-1)}{2}$-th power of its second moment.
Read the full abstract ▾
Optics
Full complex wavefunction reconstruction with direct-interference ptychography
A. Ducharme and L. Clark
We demonstrate the separable reconstruction of the sample wavefunction amplitude and phase using direct-interference ptychography in scanning transmission electron microscopy. We reconstruct the sample wavefunction in simulated and experimental data under the Weak Object Approximation (WOA) with an extension of single-sideband (SSB) ptychography using information in the double- and triple-overlap regions. The contrast transfer function for the amplitude information is equivalent to the ideal contrast transfer function of Center of Mass imaging (COM). Our results support reporting the imaginary part of SSB reconstructions.
Read the full abstract ▾
Mathematical Physics
Static equilibrium of the charged $N$-body problem
Xuhui Hu and Qinglong Zhou
We study non-collision static
equilibria in the charged \(N\)-body problem. Unlike the classical Newtonian case, such
equilibria may exist because the effective interaction coefficients $\delta_{ij}=m_im_j-e_ie_j$ can be positive, negative, or zero. We give a complete classification of three-body
equilibria and prove that all of them are collinear and linearly unstable. For the four-body problem, we derive sign restrictions for convex and concave non-collinear
equilibria, exclude non-trivial concyclic quadrilateral
equilibria, and obtain a
geometric necessary condition expressed through an auxiliary triangle and a resultant equation. We also study collinear
equilibria by reducing the force-balance equations to a homogeneous
polynomial system. This yields a resultant necessary condition and an inverse realization
theorem showing that every prescribed collinear configuration of distinct points can be realized by suitable positive masses and real charges. Finally, we analyze regular polygon configurations and centered regular polygon configurations, showing in particular that equal masses cannot form a non-trivial regular \(N\)-gon
equilibrium, while the centered case reduces to a single scalar condition.
Read the full abstract ▾
Atmospheric and Oceanic Physics
4D Parallelism Unlocks Exascale Bayesian Neural Networks for High-Fidelity Atmospheric Modeling
Deifilia Kieckhefen, Juan Pedro Gutiérrez Hermosillo Muriedas, Lars Helge Heyen et al. (+12 more)
We present BEAST, the first-ever
Bayesian Swin
Transformer for atmospheric
forecasting on 0.25$^\circ$ global resolution able to accurately quantify both aleatoric and epistemic uncertainty. To overcome the associated computational bottlenecks, we devise an orthogonal 4D-parallelization scheme that introduces a unique domain-tensor-parallelism strategy and a novel uncertainty parallel method, enabling us to fully leverage GPU capacity and efficiently scale model training. For a 2.4-billion-parameter model, we achieve a peak performance of 3.96 EFLOP/s on 20,480 NVIDIA GH200 GPUs on the JUPITER supercomputer. We train BEAST as a 700-million-parameter model with 96 random weight samples on 384 nodes on 40 years of data for nearly one million gradient updates. This model achieves predictive skill scores competitive with state-of-the-art probabilistic atmospheric AI models and numerical models, and can predict extreme events with exceptional skill, while generating large ensembles 3 to 4 times faster than the current-best AI model. Our contribution unlocks the potential of high-fidelity uncertainty quantification in atmospheric AI models, heralding a new era for AI-based models in
climate and Earth system sciences.
Read the full abstract ▾
All authors Deifilia Kieckhefen, Juan Pedro Gutiérrez Hermosillo Muriedas, Lars Helge Heyen, Mathis Bode, Iida Hakulinen, Andreas Herten, Chelsea Maria John, Thorsten Kurth, Anni Moisala, Asena Karolin Özdemir, Kaleb Phipps, Oskar Taubert, Arvid Weyrauch, Markus Götz, Charlotte Debus
High Energy Physics (Theory)
Dimensional reduction of Carroll-Field-Jackiw theory
Gabriel Condurú Magalhães
This article investigates the dimensional reduction of the massive Carroll-Field-Jackiw (CFJ) theory from $(3+1)D$ to $(2+1)D$ dimensions with the objective of constructing and analyzing the resulting effective field theory, termed pseudo-Carroll-Field-Jackiw (PCFJ). The theoretical framework relies on
quantum field theory, pseudo-
quantum electrodynamics (PQED) and Lorentz-violating models. The methodological procedure projects the three-dimensional dynamics onto the plane by rigorously integrating out the gauge field degrees of freedom along the transverse momentum. Subsequently, the study calculates the static interaction potential, applies both the generalized optical
theorem and the Källén-Lehmann spectral representation to test probability conservation. The results reveal that the effective theory exhibits an intricate non-local structure, governed by nested pseudo-differential operators, which generates a static potential that transitions from a Coulomb-like behavior at short distances to a long-range decay modified by a topological mass. The research analytically proves that the integration of the extra-dimensional
topology introduces ineliminable branch cuts in momentum space, which preclude the causal definition of asymptotic states and determine the breakdown of unitarity. The work concludes that this
quantum instability emerges from the direct interplay between the spatial projection and the pre-existing Lorentz-violating background in the bulk.
Read the full abstract ▾
High Energy Physics (Theory)
Stochastic dynamics from O(2N) fractional Laplacian vector model and O(N) vector model free energy in finite temperature
WooCheol Shin, Jun Hyuk Lee, Ji-seong Chae et al. (+1 more)
We explore O(2N) vector model with fractional
Laplacian, $\sqrt{-\nabla^2}$ in $d$-dimension and its Hamiltonain dynamics which is described by a Schrodinger type equation. This equation is a kind of current conservation equation, where one can define a current $j(\phi^a)$ of a probability $P(\phi^a)$, where $\phi^a$ is the O(2N) vector field. Naturally, Gibbs
entropy $S=-\int [D\phi^a] P(\phi^a)\log P(\phi^a)$ can be considered to explore the system. We realize that this Gibbs
entropy of the O(2N) vector model with fractional
Laplacian is matched with free energy of O(N) vector model in finite temperature, $1/\beta$ with a deformation, $\mu$ in $d$-dimension. The precise map between the
stochastic fictitious time $t$ and the inverse temperature $\beta$ is $\beta=2t$. Therefore, the temperature dependence of the thermal O(N) vector model can be realized as a dynamics of time dependent solution satisfying Schrodinger type equation. This free energy is obtained by putting O(N) vector model in $S^1\times \mathbb R_d$, where $S^1$ is thermal circle with its periodicity $\beta$. To get $d$-dimensional theory, we sum up all possible frequencies on the circle(so called Matsubara frequency summation) which gives $d$-dimensional thermal partition function. We note that the nontrivial $t$-dependence appears beyond classical limit. To take into account
quantum effects, we solve the
Hamiltonian dynamics by keeping $\hbar$ corrections. The spectral deformation is mediated by a parameter $l$ such that $\mu=\beta^{-1}\log l$ and so we call this $l$-deformation. This is related to the initial boundary condition of the Schrodinger equation. We also note that the two theoreis are not equivalent each other and we just check their correspondence in the level of one-loop determinant, i.e. zero point function in the note.
Read the full abstract ▾
All authors WooCheol Shin, Jun Hyuk Lee, Ji-seong Chae, Jae-Hyuk Oh
High Energy Physics (Phenomenology)
Reconstructing the Dark Matter Equation of State with Compact Object Inspirals
Boris Betancourt Kamenetskaia, Qianhang Ding and Hui-Yu Zhu
We investigate the gravitational wave (GW) signatures of compact binaries embedded in extended dark matter (DM) configurations in hydrostatic
equilibrium. If a
neutron star is surrounded by a sufficiently massive and extended envelope, an inspiraling companion experiences dynamical friction (DF) in addition to the standard GW energy loss. We show that this environmental effect can be isolated through a GW observable, the $D$-function, which directly characterizes the additional dissipative power induced by the surrounding medium. Since the density of the envelope is directly determined by the DM equation of state together with the
stellar boundary conditions, the frequency dependence of the $D$-function provides direct information about the macroscopic properties of the dark sector. We develop a regression-based framework to reconstruct both the density profile and the DM equation of state over the density range probed by observations of the GW inspiral. Using representative DM models as
benchmarks, we demonstrate that the method accurately recovers the input equation of state while remaining largely independent of the microscopic realization of DM. Our results show that future GW observations of compact binaries can provide a probe of the equation of state of DM.
Read the full abstract ▾
Mathematical Physics
Random field approximation and local counting statistics for the weakly interacting thermal Bose gas
Andreas Deuchert, Marcin Napiórkowski and Błażej Ruba
We study weakly interacting
bosons on the three-dimensional
torus at temperatures proportional to the critical temperature for Bose–Einstein condensation. We show that, as the expected particle number tends to infinity, the grand canonical Gibbs state is asymptotically described by the coherent state quantization of a random field that converges to a novel Bogoliubov random field. Moreover, the point process associated with the Gibbs state can be approximated by a Cox process. These results are based on and extend the approximation of the Gibbs state recently obtained by the first two authors and Nam. Using these approximations, we compute limiting distributions of the number of particles outside the condensate, the joint occupation statistics of finitely many momentum modes, and particle-number fluctuations in macroscopic subsets of the
torus, all governed by the Bogoliubov field. We further prove convergence of the empirical measure of the associated point process to the uniform measure and convergence of the microscopic particle-number statistics to the
boson point process. The latter result establishes the universality of particle-number statistics on microscopic length scales.
Read the full abstract ▾
Quantum Physics
Testing and Diagnosing Parameter Miscalibration in Probabilistic Error Cancellation via Direct Fidelity Estimation
Francesc Sabater, Tristan Kraft, Carlos A. Riofrío et al. (+1 more)
Probabilistic Error Cancellation (PEC) is a standard technique for mitigating noise in
quantum computations, but its unbiasedness relies on accurate knowledge of the underlying noise parameters. In practice, these parameters are inferred from experimental data and may be inaccurate. We introduce a protocol that tests PEC parameter consistency on hardware by applying Direct Fidelity Estimation (DFE) to the effective mitigated state. The resulting DFE overlap serves not only as a witness of parameter miscalibration but, under appropriate conditions, also reveals whether the PEC parameters have been overestimated or underestimated. We establish this behavior for arbitrary
circuits under global depolarizing noise and for Clifford
circuits under general Pauli-
stochastic noise. For arbitrary
circuits subject to Pauli-
stochastic noise, the underestimation result holds generally, while the corresponding overestimation result is established perturbatively for sufficiently small consistent miscalibrations under an additional nondegeneracy condition. We further show that the purity of the effective mitigated operator provides a more general diagnostic, allowing the miscalibration direction to be identified for arbitrary
circuits and arbitrary parameter deviations. Finally, we describe a two-copy PEC procedure for measuring this quantity and show that, together with the DFE overlap, it determines the
Hilbert-Schmidt distance from the ideal state. The sampling overhead incurred by our protocol is the same as that of PEC, and we discuss strategies to improve it.
Read the full abstract ▾
All authors Francesc Sabater, Tristan Kraft, Carlos A. Riofrío, Barbara Kraus
Data Analysis and Statistics · Cross-listed from cs.AI
Interpreting the predictions of neural network classification based on a Taylor Coefficient Analysis (TCA)
Markus Klute, Artur Monsch, Lars Sowa et al. (+1 more)
We introduce a rigid and comprehensive taxonomy and paradigm for characterizing the influence of the input feature space $X$ on the predictions $\hat{y}$ of a neural network (NN) used for event classification, based on a Taylor expansion of $\hat{y}$ in $X$. The complete process of introspection we refer to as Taylor Coefficient Analysis (TCA). Based on two simplistic example tasks, which can be easily understood and bencmarked, we illustrate the power of the TCA when it comes to revealing, what properties of $X$ have led to what value of $\hat{y}$, of a given NN model, building up intuition for the method. A more complex application is meant to represent $X$ of a typical classification task at a CERN LHC experiment. Based on this application, we play through the different levels of introspection that the TCA offers and discuss a number of practical aspects for a TCA application typical for the analysis of CERN LHC data. We conclude with a study to support the assumption that those properties of $X$ most relevant for tasks of the complexity typical for a CERN LHC experiment, are usually caught by a TCA up to the second order.
Read the full abstract ▾
All authors Markus Klute, Artur Monsch, Lars Sowa, Roger Wolf
High Energy Physics (Phenomenology)
Associated $W$ + charm production: indications for PDF analysis
Ville Alanko, Ilkka Helenius and Hannu Paukkunen
The strange
quark and antiquark contents of the
proton remain weakly constrained compared to the other light
quarks, particularly the asymmetry between the two. Production of a $W^\mp$
boson in association with a charmed
meson $D^{(*)\pm}$ could provide additional constraints in future fits of parton distribution functions. We calculate this process in general-mass variable-
flavor-number scheme at next-to-leading order in perturbative
Quantum Chromodynamics. We investigate the production ratio between events with oppositely charged $W$
bosons, in which various theoretical uncertainties largely cancel while sensitivity to PDFs remains. We compare our predictions for this quantity with the recent ATLAS data at $\sqrt{s} = 13$ TeV and find that CT18ANLO, which sets the strangeness asymmetry to zero, yields good agreement with the data while MSHT20NLO and NNPDF4.0NLO, which have positive strangeness asymmetry in the relevant range of momentum fraction $x$, show more tension with the data. An approximate PDF-level analysis of the production ratio indicates that this tension could be attributed to a too large strangeness asymmetry.
Read the full abstract ▾
Instrumentation and Detectors
Surface Commissioning and Performance of the sMDT Muon Chambers for the ATLAS HL-LHC Upgrade
Jiajin Ge, Elena Voevodina, Hubert Kroha et al. (+21 more)
To improve the first-level
muon trigger efficiency at the HL-LHC, the Monitored Drift Tube (MDT) chambers in the inner small sectors of the ATLAS Barrel
Muon Spectrometer will be replaced with integrated modules of small-Diameter
Muon Drift Tube (sMDT) and Resistive Plate Chambers (RPCs). This paper reports on the surface commissioning of 102 new sMDT chambers at CERN in 2025 following the installation of the final front-end electronics, including the new Amplifier-Shaper-Discriminator (ASD), Time-to-Digital Converter (TDC) chips, and Chamber Service Module (CSM) developed for the HL-LHC. The commissioning included measurements of gas leak rates and high-voltage dark currents, tests of the integrated planarity monitoring system, noise characterization, and measurements of detector efficiency and spatial resolution using
cosmic rays. Fewer than 0.1% of the 49152 tubes were found to be non-functional due to broken sense wires or gas leaks. The chambers exceed the ATLAS design requirements, with gas leak rates a factor of five below the specified limit of $9.3\times 10^{-3}~\mathrm{mbar\cdot liter/s}$ per chamber, dark currents of only around 0.2~nA per tube, average channel noise hit rates below 30~Hz, and average drift tube efficiency and spatial resolution of 99% and $82~\mu\mathrm{m}$, respectively, at an effective threshold of 15 primary electrons.
Read the full abstract ▾
All authors Jiajin Ge, Elena Voevodina, Hubert Kroha, Tatiana Azaryan, Kwok Ching Cheung, Tiesheng Dai, Edward Diehl, Claudio Ferretti, Yuxiang Guo, Oliver Kortner, Chihao Li, Chun Kit Lo, Nick Meier, Emmett Salzer, Can Suslu, Cecilia Vanesa Imthurn, Samuel Hugo Venetianer, Curtis Weaverdyck, Chuanshun Wei, Bastian Michael Wesely, Ruslan Yakubovych, Bing Zhou, Junjie Zhu, Jörg Zimmermann
General Relativity and Quantum Cosmology
The Wavelet Detection Filter: a real time unmodeled pipeline for gravitational wave transients, ranking coincidences with a graph neural network
Elena Cuoco
Accurate waveform models are unavailable for many potential sources of gravitational wave transients, motivating searches that do not assume a predefined template family. The Wavelet Detection Filter (WDF) is an unmodeled pipeline that identifies excess energy in the wavelet coefficients of whitened detector data. Here, we develop WDF into a low latency pipeline for both detection and reconstruction and this paper describes and validates that pipeline. We use a zero phase streaming autoregressive whitening filter that preserves transient morphology with a fixed latency and we use the retained wavelet coefficients to provide both a detection statistic and a sparse representation of the signal. By combining coefficients across consecutive analysis windows, the pipeline reconstructs transients longer than a single window. We represent candidate coincidences between detectors with a trigger graph and rank them with supervised and unsupervised graph neural networks (GNNs). We estimate the significance of the ranked coincidences from time shifted data. We validate the pipeline on Gaussian noise colored according to the Advanced LIGO sensitivity curve and on real O4 strain containing compact binary and core collapse
supernova injections. Applied to GW250114, WDF identifies the event as the loudest zero lag candidate in the analyzed segment without using waveform templates. We measure the computational cost of the pipeline and the latency it introduces. Both are compatible with a low latency search,so WDF can run on a stream in real time.
Read the full abstract ▾