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2603.18628 2026-03-27 math.OC math.PR

Robust mean-field games under entropy-based uncertainty

François Delarue, Pierre Lavigne

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英文摘要

In this article, we introduce a new class of entropy-penalized robust mean field game problems in which the representative agent is opposed to Nature. The agent's objective is formulated as a min-max stochastic control problem, in which Nature distorts the reference probability measure at an entropic cost. As a consequence, the distribution of the continuum of agents represented by the player is given by the effective measure induced by Nature. Existence of a mean-field game equilibrium is established via a Schauder fixed point argument. To ensure uniqueness, we introduce a joint flat anti-monotonicity and displacement monotonicity condition, extending the classical Lasry-Lions monotonicity framework. Finally, we present two classes of N -player games for which the mean-field game limit yields $ε$-Nash equilibria.

2603.17410 2026-03-27 quant-ph

Stabilizing correlated pair tunneling of spin-orbit-coupled bosons in a non-Hermitian driven double well

Miaoqian Lu, Xinzhou Guan, Mohan Xia, Wenjuan Li, Jincheng Hu, Xinyue Zhang, Yunrong Luo

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英文摘要

We present an analytical framework for stabilizing second-order correlated tunneling of two spin-orbit-coupled bosons in a periodically driven non-Hermitian double-well potential. By combining Floquet theory with multiple-scale asymptotic analysis, we derive effective second-order dynamics and exact quasienergy spectra in the strongly interacting regime. Our analysis reveals distinct stability mechanisms for three fundamental tunneling channels: interwell spin-conserving, interwell spin-flipping, and intrawell spin-flipping. For balanced gain and loss, we identify discrete, well-defined parameter regions where stable pair tunneling emerges, with the spin-flipping channel exhibiting a characteristic symmetry absent in its spin-conserving counterpart. Under unbalanced gain-loss conditions, stability is achieved only when the gain and loss coefficients satisfy specific parametric relations, enabling dissipation-controlled tunneling. Most notably, stable intrawell spin-flipping, while inherently unstable for an initial Fock state, becomes accessible when the system is prepared in a coherent superposition state, thereby revealing that initial-state coherence can serve as a control parameter for dynamical stability in non-Hermitian systems. These results expand the possibilities for controlling correlated tunneling in many-body systems with engineered dissipation.

2603.17083 2026-03-27 astro-ph.SR astro-ph.GA astro-ph.IM

Stellar characterization with photometric colors from J-PLUS and 2MASS surveys

J. F. Aguilar, P. Cruz, E. Solano, P. R. T. Coelho, A. Ederoclite, V. M. Placco, P. Mas-Buitrago, A. Alvarez-Candal, A. J. Cenarro, D. Cristóbal-Hornillos, C. Hernández-Monteagudo, C. López-Sanjuan, A. Marín-Franch, M. Moles, J. Varela, H. Vázquez Ramió, J. Alcaniz, R. A. Dupke, L. Sodré, R. E. Angulo

Comments Submitted to the Astronomy and Astrophysics Journal

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Aims. We aim at deriving stellar atmospheric parameters based on the photometric data from the Javalambre Photometric Local Universe Survey (J-PLUS) in addition to near-infrared photometry from the Two Micron All-Sky Survey (2MASS). Methods. Our method consists of a semi-supervised machine learning approach based on the k-means method combined with a modified k-nearest neighbors algorithm. This method compares the observed photometry to a set of reference data to estimate the stellar effective temperature ($T_{\rm eff}$), surface gravity ($\log{g}$), and metallicity ([Fe/H]) of stars from J-PLUS Data Release 3 (DR3). Results. We estimated $T_{\rm eff}$, $\log{g}$, and [Fe/H], for approximately 5.6 million stars from J-PLUS DR3, along with their errors.Our results were in agreement with spectroscopic estimates from LAMOST and APOGEE.We also applied a dimension reduction method, seeking greater efficiency by reducing the computation time and minimizing the needed information for calculating the stellar parameters, resulting in a subset of 11 colors. From this approach, stellar parameters were obtained for approximately six million stars. Conclusions. Our results demonstrated the potential of using a method built from machine learning algorithms that do not require prior training. Additionally, it was shown that the proposed method allowed estimating reliable atmospheric parameters even when the available photometry did not fulfill all photometric quality criteria. We defined a neighborhood parameter, which assesses the reliability of our estimations and indicates that objects with smaller neighborhoods values have lower uncertainties.

2603.17004 2026-03-27 astro-ph.CO gr-qc hep-ph hep-th

What Shape is the Inflationary Bispectrum?

Oliver H. E. Philcox

Comments 5+9 pages, 3+4 figures, submitted to Phys. Rev. Lett. Comments welcome!

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Non-linear interactions during inflation generate non-Gaussianities in the distribution of primordial curvature. In many theories, the physics is scale-invariant, such that the induced three-point function depends solely on a dimensionless shape function $S(x,y)\sim k^6B_ζ(kx,ky,k)$. To confront such models with observations, one typically builds specialized estimators for each shape, then applies them to cosmic microwave background datasets at significant computational expense. In this Letter, we take a different approach, directly reconstructing $S(x,y)$ from observations using an efficient logarithmically-binned estimator in primordial-space (motivated by the modal program). Applying this to temperature and polarization maps from Planck, we obtain high-resolution shape measurements across the full $(x,y)$-plane, including squeezed limits. Our approach is close-to-optimal, highly interpretable, and preserves the information content on (optimally-analyzed) standard templates within $\approx 10\%$; moreover, we can use it to assess the scale-dependence of our constraints, finding that Planck is sensitive to $\approx 6$ $e$-folds of non-Gaussian evolution with a peak sensitivity around $0.1h\,\mathrm{Mpc}^{-1}$. Since we work directly in shape-space, data and theory can be compared in milliseconds. As an example, we perform a search for massive particle exchange using a suite of over $20\,000$ theoretical templates computed with exact bootstrap methods (for the first time) across a wide range of masses, spins, and sound-speeds; the spin-two analysis yields a maximum significance of $2.6σ$. Our approach can be used to probe a wide range of scale-invariant models in orders-of-magnitude less time than with direct estimators, allowing the inflationary paradigm to be explored in new ways.

2603.16786 2026-03-27 cs.DS cs.PF

Elastic Sketch under Random Stationary Streams: Limiting Behavior and Near-Optimal Configuration

Younes Ben Mazziane, Vinay Kumar B. R., Othmane Marfoq

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Elastic-Sketch is a hash-based data structure for counting item's appearances in a data stream, and it has been empirically shown to achieve a better memory-accuracy trade-off compared to classical methods. This algorithm combines a heavy block, which aims to maintain exact counts for a small set of dynamically elected items, with a light block that implements Count-Min Sketch (CM) for summarizing the remaining traffic. The heavy block dynamics are governed by a hash function $β$ that hashes items into $m_1$ buckets, and an eviction threshold $λ$, which controls how easily an elected item can be replaced. We show that the performance of Elastic-Sketch strongly depends on the stream characteristics and the choice of $λ$. Since optimal parameter choices depend on unknown stream properties, we analyze Elastic-Sketch under a stationary random stream model -- a common assumption that captures the statistical regularities observed in real workloads. Formally, as the stream length goes to infinity, we derive closed-form expressions for the limiting distribution of the counters and the resulting expected counting error. These expressions are efficiently computable, enabling practical grid-based tuning of the heavy and CM blocks memory split (via $m_1$) and the eviction threshold $λ$. We further characterize the structure of the optimal eviction threshold, substantially reducing the search space and showing how this threshold depends on the arrival distribution. Extensive numerical simulations validate our asymptotic results on finite streams from the Zipf distribution.

2603.15593 2026-03-27 cond-mat.mes-hall

Flat-Band Generation in InAs/GaSb Quantum Wells through Vertically Engineered Heterostructures

Zachery A. Enderson, Jiyuan Fang, Wei-Chen Wang, Li Xiang, Mykhaylo Ozerov, Dmitry Smirnov, Zhigang Jiang, Samuel D. Hawkins, Aaron J. Muhowski, John F. Klem, Wei Pan

Comments 12 pages, 6 figures

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Quantum materials constitute a novel category of substances wherein quantum effects and electron-electron (e-e) interactions give rise to unforeseen phenomena on a macroscopic scale. Of particular interest within the realm of quantum materials are flat bands, which promote heavy conduction electrons and enhance e-e correlation effects. While the engineering of such flat bands has been demonstrated in graphene and two-dimensional transition metal dichalcogenides moiré superlattices and in lithography defined semiconductor moiré superlattices, conventional tear-and-stack fabrication methods face challenges due to inevitable twist-angle disorder, strain, and relaxation effects, leading to issues with reproducibility and scalability. Here, we explore the creation and modification of flat bands through vertically engineered III-V semiconductor heterostructures, without the need for twisting. These artificial quantum materials offer a reproducible and scalable means for producing high-quality flat-band materials via molecular beam epitaxy growth. Our investigation includes magnetotransport and infrared magneto-spectroscopy studies of quad-layer InAs/GaSb quantum wells, accompanied by k*p band structure calculations, which illustrate the flattening of bands in vertically designed heterostructures.

2603.14502 2026-03-27 math.PR

The Non-Gaussian to Gaussian Transition: Pointwise Heat Kernel Estimates and Optimal Convergence Rates

Xianming Liu, Chongyang Ren, Mingyan Wu

Comments 33

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We establish uniform pointwise estimates for the densities of a family of $α$-stable processes with respect to the index $α\in [α_0,2]$ for some $α_0>0$. In addition, we estimate the difference between the heat kernels of non-local and local operators, showing that it is controlled by the rate $2-α$. Both estimates (see Proposition 2.4) are new to the literature. Furthermore, as an application, we achieve the optimal rate $2-α$ for the pointwise estimate between the transition probabilities, as well as for the (weighted) total variation and Kantorovich distances between the invariant measures, of non-Gaussian and Gaussian diffusion. These results are obtained under the assumption that the drifts are locally $β$-Hölder continuous, with the latter additionally requiring dissipativity. The results on transition probabilities (see Theorem 2.3) are novel, while those on invariant measures (see Theorem 2.7) significantly extend the existing literature.

2603.13913 2026-03-27 math.LO

Axiom Beta Implies Elementary Transfinite Recursion

Emanuele Frittaion, Giorgio G. Genovesi

Comments 42 pages

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We show that $\mathbf{C}$, a weak theory of sets with Axiom Beta, proves the scheme of Elementary, or $Δ_0$ Transfinite Recursion and can generate, for every set, the corresponding relativized constructible hierarchy. We show that the theory $\mathbf{C}$ corresponds to Simpson's system $\mathbf{ATR}_0^\text{set}$ without the Axiom of Countability. In fact, $\mathbf{C}$ proves the totality of the Veblen function and of all primitive recursive set functions. In particular, this means our system $\mathbf{C}$ is equivalent to $\mathbf{PRS}ω+\text{Axiom Beta}$. We also establish an upper bound, though not a sharp one, for the $Σ_1$-definable functions of $\mathbf{C}$. Finally, we show that the variant of $\mathbf{C}$ in which the Finite Powerset Axiom is replaced by the closure under the rudimentary functions is a strictly weaker theory and no longer ensures the existence of the relativized constructible hierarchy.

2603.13778 2026-03-27 cond-mat.dis-nn cond-mat.stat-mech cs.ET math.DS physics.data-an

Optimality and annealing path planning of dynamical analog solvers

Shu Zhou, K. Y. Michael Wong, Juntao Wang, David Shui Wing Hui, Daniel Ebler, Jie Sun

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Recently proposed analog solvers based on dynamical systems, such as Ising machines, are promising platforms for large-scale combinatorial optimization. Yet, given the heuristic nature of the field, there is very limited insight on optimality guarantees of the solvers, as well as how parameter schedules shape dynamics and outcomes. Here, we develop a dynamical mean-field framework to analyze Ising-machine dynamics for finding the ground state energy of the Sherrington-Kirkpatrick(SK) model of spin glasses and identify mechanisms that enable rapid convergence to provenly near-optimal energies. For a fixed target energy density Ec, we show that solutions are typically reached within O(1) matrix vector multiplications, indicating constant time complexity. We further delineate theoretical limitations arising from different parameter-scheduling trajectories and demonstrate a pronounced benefit of temperature-only annealing for the Coherent Ising Machine. Building on these insights, we propose a general framework for designing optimized parameter schedules, thereby improving the practical effectiveness of Ising machines for complex optimization tasks. The superior performance of the dynamical solvers is illustrated by the attainment of the ground state energy of the SK model.

2603.11156 2026-03-27 quant-ph

Low $T$-count preparation of nuclear eigenstates with tensor networks

Joe Gibbs, Lukasz Cincio, Chandan Sarma, Zoë Holmes, Paul Stevenson

Comments 15 pages, 10 figures

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We present an efficient protocol leveraging classical computation to support Initial State Preparation for strongly correlated fermionic systems, a critical bottleneck for fault-tolerant quantum simulation. Focusing on nuclear shell model eigenstates, we first demonstrate that the Density Matrix Renormalization Group algorithm can efficiently approximate target states as Matrix Product States, capitalizing on the favourable entanglement structure of these fermionic systems. These high-fidelity approximations are then leveraged as a classical resource in a variational circuit optimization scheme to compile shallow quantum circuits. We establish concrete resource estimates by decomposing the resulting circuits into the industry-standard Clifford$+T$ gateset, exploring the benefits of specialized $U3$ synthesis techniques. For all nuclear systems tested, on up to 76 qubit Hamiltonians, we consistently find low $T$-count circuits preparing the nuclear eigenstates to high fidelity with $\sim 2\times 10^4$ total $T$ gates. This low number gives confidence these eigenstates can be prepared on early fault-tolerant quantum computers. Our work establishes a viable path toward practical ground state preparation for nuclear structure and other fermionic applications.

2603.10625 2026-03-27 cs.DB cs.IR

A Hypergraph-Based Framework for Exploratory Business Intelligence

Yunkai Lou, Shunyang Li, Longbin Lai, Jianke Yu, Wenyuan Yu, Ying Zhang

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Business Intelligence (BI) analysis is evolving towards Exploratory BI, an iterative, multi-round exploration paradigm where analysts progressively refine their understanding. However, traditional BI systems impose critical limits for Exploratory BI: heavy reliance on expert knowledge, high computational costs, static schemas, and lack of reusability. We present ExBI, a novel system that introduces the hypergraph data model with operators, including Source, Join, and View, to enable dynamic schema evolution and materialized view reuse. Using sampling-based algorithms with provable estimation guarantees, ExBI addresses the computational bottlenecks, while maintaining analytical accuracy. Experiments on LDBC datasets demonstrate that ExBI achieves significant speedups over existing systems: on average 16.21x (up to 146.25x) compared to Neo4j and 46.67x (up to 230.53x) compared to MySQL, while maintaining high accuracy with an average error rate of only 0.27% for COUNT, enabling efficient and accurate large-scale exploratory BI workflows.

2603.10449 2026-03-27 physics.ins-det physics.optics

Development of an Extensible Unified Control System Using the STARS Framework and Common Commands for Detector Control

Ryutaro Nishimura, Yuki Shibazaki, Daisuke Wakabayashi, Yoshio Suzuki, Keiichi Hirano, Hiroaki Nitani, Takashi Kosuge, Noriyuki Igarashi

Comments Preprint of full-length article for Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Elsevier

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Two Fresnel zone plates zooming optics have been successfully developed and installed at the AR-NE1A beamline of the Photon Factory at the high energy accelerator research organization (KEK) in Japan. To ensure the reliable and versatile operation of this optical instrumentation, a dedicated control architecture has been implemented based on the simple transmission and retrieval system (STARS) framework, incorporating the newly proposed STARS common commands for detector control (CCDC) -- a detector-specific data acquisition (DAQ) state and command system. This system serves as both a practical control system for zooming optics and a demonstration model for modular extensibility using the STARS framework and inter-operability among detector systems enabled by the CCDC command set. The system has been commissioned, and its performance has been verified at the AR NE1A beamline. The control architecture affords enhanced configurational flexibility for optical components and provides an interface appropriate for both routine users and advanced experimental protocols.

2603.09779 2026-03-27 math.SP math-ph math.MP

Patterson-Sullivan distributions of finite regular graphs

Christian Arends, Guendalina Palmirotta

Comments 38 pages, 3 figures; v2: added references

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On finite regular graphs, we construct Patterson-Sullivan distributions associated with eigenfunctions of the discrete Laplace operator via their boundary values on the phase space. These distributions are closely related to Wigner distributions defined via a pseudo-differential calculus on graphs, which appear naturally in the study of quantum chaos. Using a pairing formula, we prove that Patterson-Sullivan distributions are also related to invariant Ruelle distributions arising from the transfer operator of the geodesic flow on the shift space. Both relationships provide discrete analogues of results for compact hyperbolic surfaces obtained by Anantharaman-Zelditch and by Guillarmou-Hilgert-Weich.

2603.09352 2026-03-27 quant-ph

Elementary asymptotic approach to the Landau-Zener problem

Eric P. Glasbrenner, Wolfgang P. Schleich

Comments 16 pages, 5 figures

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We present an asymptotic approach towards the standard Landau-Zener problem based on two linearly independent elementary waves of constant amplitude but time-dependent phase. The two contributions to this phase are quadratic and logarithmic in time and result from the linear chirp of the energies and the lowest order correction in the coupling between the two levels in the long-time limit. Indeed, our solutions subjected to initial conditions at a large but finite time in the past, are valid for large negative and large positive times. Due to their asymptotic nature they are not valid in the neighborhood of the moment when the levels cross. However, as the starting point of the dynamics moves further into the past, the time interval of the break-down of our asymptotic solutions shrinks and vanishes in the limit of the infinite past which corresponds to the standard Landau-Zener situation. Our approach explains not only every feature of the exact solution but yields deeper insights into the origin of the effects. In particular, it (i) brings to light the subtleties involved in the asymptotic limit leading to the standard expressions for the Landau-Zener transition amplitudes, (ii) identifies the logarithmic phase as the origin of the exponential transition probability amplitude, and (iii) reveals the structure of the lowest order corrections to the Landau-Zener result when the starting point is not in the infinite past.

2603.08471 2026-03-27 math.OC cs.CC cs.IT math.IT

Intrinsic Sequentiality in P: Causal Limits of Parallel Computation

Jing-Yuan Wei

Comments We introduce the Hierarchical Temporal Relay (HTR) model, capturing computations whose semantics require hop-by-hop causal execution. Using information-theoretic tools, we prove that any implementation respecting causal communication constraints requires Ω(N) time, showing that such processes cannot be compressed into polylogarithmic-depth parallel computation

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We study a polynomial-time decision problem in which each input encodes a depth-$N$ causal execution in which a single non-duplicable token must traverse an ordered sequence of steps, revealing at most $O(1)$ bits of routing information at each step. The uncertainty in the problem lies in identifying the delivery path through the relay network rather than in the final accept/reject outcome, which is defined solely by completion of the prescribed execution. A deterministic Turing machine executes the process in $Θ(N)$ time. Using information-theoretic tools - specifically cut-set bounds for relay channels and Fano's inequality - we prove that any execution respecting the causal constraints requires $Ω(N)$ units of causal time, thereby ruling out asymptotic parallel speedup. We further show that no classical $\mathbf{NC}$ circuit family can implement the process when circuit depth is interpreted as realizable parallel time. This identifies a class of polynomial-time problems with intrinsic causal structure and highlights a gap between logical parallelism and causal executability.

2603.08319 2026-03-27 cond-mat.mtrl-sci

Structural phase transitions in double perovskite crystals studied by Brillouin light scattering

D. O. Horiachyi, M. O. Nestoklon, I. A. Akimov, D. R. Yakovlev, V. Vasylkovskyi, O. Trukhina, V. Dyakonov, M. Bayer

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Inorganic lead-free double perovskites represent particular interest as non-toxic and stable material platform for optoelectronic applications. Here, we employ Brillouin light scattering spectroscopy to investigate the elastic properties and structural phase transitions in single crystals of Cs2AgBiBr6 and Cs2AgBiCl6. A complete set of elastic constants is determined from the Brillouin scattering measurements performed along three different crystallographic directions. Both materials exhibit similar elastic constants and weak elastic anisotropy in the cubic phase. At low temperatures, the lifting of degeneracy of transverse acoustic phonon modes is attributed to a lowering of crystal symmetry. From the temperature dependence of the acoustic phonon frequencies, we determine the structural phase transition temperature of about 43 K for Cs2AgBiCl6, compared to 122 K for the cubic-to-tetragonal phase transition in Cs2AgBiBr6.

2603.06754 2026-03-27 physics.data-an hep-ex

Learning the Standard Model Manifold: Bayesian Latent Diffusion for Collider Anomaly Detection

Jigar Patel, Tommaso Dorigo

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We propose a physics-informed anomaly detection framework for collider data based on a Bayesian latent diffusion model. Our method combines a probabilistic encoder with diffusion dynamics in the latent space, allowing for stable and flexible density estimation while explicitly enforcing physics constraints, such as mass decorrelation and regularization of latent correlations. We train and test the model on simulated LHC jet data and evaluate its performance using seed-averaged ROC curves together with discovery-oriented metrics. Through a series of ablation studies, we show that the diffusion process, Bayesian regularization, and physics-motivated loss terms each contribute in a complementary way: they help stabilize training and improve generalization, even when the gains in peak performance are moderate. Overall, our results emphasize the importance of incorporating both uncertainty estimates and physics consistency when building reliable anomaly detection methods for new Physics searches in high-energy physics.

2603.06511 2026-03-27 gr-qc hep-lat quant-ph

Hybrid quantum-classical simulations of semiclassical gravity

Carlos Fulgado-Claudio, Daniel González-Cuadra, Jose Beltrán Jiménez, Alejandro Bermudez

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We propose a hybrid quantum-classical algorithm for the simulation of real-time dynamics in interacting quantum field theories coupled to classical fields, focusing on the self-consistent estimation of semiclassical backreaction. By discretizing space and time, we construct an iterative protocol that simulates the Trotterized dynamics of the quantum fields subject to the dynamical classical fields. By estimating certain quantum expectation values through a set of projective measurements, we source the equations of motion of the classical fields, and solve them numerically to feed them forward to the quantum simulation in an iterative self-consistent loop. Semiclassical backreaction is relevant in various fields of physics, particularly in cosmology, where quantum matter fluctuations affect the gravitational field dynamics, and a controlled renormalization must be carefully considered to get a sensible continuum limit. We benchmark our algorithm in this context, focusing on scalar-tensor theories of modified gravity exhibiting a chameleon mechanism, such that a light classical scalar field driving cosmic acceleration becomes massive in high-density regions, effectively screening any possible yet unobserved fifth force. By focusing on numerically tractable regimes, we explicitly show the convergence and robustness of our algorithm when considering the continuum limit and the effect of quantum shot noise. Our work paves the way for future experiments exploring other non-tractable regimes, including non-perturbative interactions of the quantum fields and how these can change backreaction and the gravitational dynamics.

2603.06145 2026-03-27 math.OC

Policy Iteration Achieves Regularized Equilibrium under Time Inconsistency

Yu-Jui Huang, Xiang Yu, Keyu Zhang

Comments Keywords: Time inconsistency, entropy regularization, exploratory equilibrium Hamilton--Jacobi-Bellman equations, regularized equilibrium policies, policy iteration, rate of convergence

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For a general entropy-regularized time-inconsistent stochastic control problem, we propose a policy iteration algorithm (PIA) and establish its convergence to an equilibrium policy with an exponential convergence rate. The design of the PIA is based on a coupled system of non-local partial differential equations, called the exploratory equilibrium Hamilton--Jacobi--Bellman (EEHJB) equation. As opposed to the standard time-consistent case, policy improvement fails in general and the target value function (now an equilibrium value function) is not even known to exist a priori. To overcome these, we prove that the value functions generated by the PIA form a Cauchy sequence in a specialized Banach space, hence admit a limit, and the rate of convergence is exponential, on the strength of the Bismut--Elworthy--Li formula of stochastic representation. The limiting value function is shown to fulfill the EEHJB equation, which induces an equilibrium policy in a Gibbs form. Such convergence in value additionally implies uniform convergence of the generated policies to the equilibrium policy, again with an exponential rate. As a byproduct, the PIA gives a constructive proof of the global existence and uniqueness of a classical solution to our general EEHJB equation, whose well-posedness has not been explored in the literature.

2603.05155 2026-03-27 hep-lat

Discretisation effects of gradient flows in QCD-like theories on the lattice

Pietro Butti, Michele Della Morte, Benjamin Jäger, Sofie Martins, J. Tobias Tsang

Comments Contribution to PoS for The 42nd International Symposium on Lattice Field Theory (LATTICE2025), November 2-8 2025, TIFR, Mumbai, India

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Recent software advances now allow large-scale lattice studies of the Corrigan--Ramond large-$N_C$ limit of Yang-Mills theory coupled with a two-index antisymmetric fermion, providing a path to SUSY Yang-Mills. We are currently generating ensembles for $N_C=4,5,6$ for lattice spacings in the range $0.11 - 0.08$ fm. We report on two aspects of our work: the study of topological properties as well as estimates of discretisation effects. The first aspect is relevant since naively, fractional topological charges might be expected in our simulations. Using a gluonic definition of the topological charge combined with gradient flow, we perform an analysis of the effect of different discretisations of the kernel action, from which we identify and interpret quantitative differences between Wilson and over-improved flows such as DBW2. The second aspect is addressed by considering ratios of different reference flow times. We conclude that our current simulations might be affected by discretisation effects of order 10\%.

2603.03264 2026-03-27 astro-ph.SR

A fast method for deriving relative small-scale magnetic field variations from high-resolution spectroscopy

Paul I. Cristofari, Steven H. Saar, Aline A. Vidotto, Stefano Bellotti

Comments 14 pages, 17 figures including appendix, accepted for publication in A&A

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Observational constraints on stellar magnetic fields are essential to both stellar and planetary physics. Recent studies revealed the diversity and evolution of large-scale magnetic fields in low-mass stars. These large-scale fields only account for a small fraction of the observed unsigned magnetic flux. Most of the surface magnetic flux if accounted for by small (spatial) scale magnetic fields, which exhibit clear temporal evolution of time scales of years. We aim at developing new techniques to extract small-scale magnetic field estimates from time series of observed spectra. Our ultimate goal is to study the temporal evolution of small-scale magnetic fields which will provide insight into the magnetic properties of low-mass stars and their magnetic cycles. We implement a process to capture relative pixel variations caused by changes in magnetic field strengths, relying on synthetic spectra computed with ZeeTurbo. This approach provides extremely fast and reliable estimates of relative magnetic field strength variations from series of high-resolution spectra, mitigating the impact of systematics between models and observations. We assess the performance of the proposed method through its application to simulated data and publicly available spectra. In addition, we implement a model-driven process to derive relative temperature variations and explore the influence magnetic fields have on these measurements. Our results are in excellent agreement with previous magnetic field estimates. The method provides robust constraints and proves to be relatively insensitive to small changes in the assumed atmospheric parameters and broadening. We find that magnetic field variations have the potential of introducing biases in relative temperature estimates, in particular for domains containing a large number of magnetically-sensitive transitions.

2603.02307 2026-03-27 gr-qc math.AP

Global existence for a Fritz John equation in expanding FLRW spacetimes

João L. Costa, Jesús Oliver, Flavio Rossetti

Comments 23 pages; v2: references updated

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We study the family of semilinear wave equations $\square_{\mathbf{g}_p}ϕ=(\partial_tϕ)^2$, on fixed expanding FLRW spacetimes, having $\mathbb{R}^3$ spatial slices and undergoing a power law expansion, with scale factor $a(t)=t^p$, $0< p \le 1$. This is a natural generalization to a non-stationary background of a famous Fritz John ''blow-up'' equation in $\mathbb{R}^{1+3}$ (corresponding to $p=0$, i.e. the case in which $\mathbf{g}_0$ is the Minkowski metric). While, in Minkowski spacetime ($p=0$), non-trivial solutions to this equation are known to diverge in finite time, here we prove that, on the referred FLRW backgrounds ($0<p\leq 1$), sufficiently small, smooth, and compactly supported initial data yield global-in-time solutions to the future. Previous work, co-authored by the first two authors, considered accelerated expanding spacetimes ($p>1$) and relied on the integrability of the inverse of the scale factor to establish future global well-posedness. In the current work, where such an integrability condition is lacking, we rely on a vector field method that captures and combines dispersive estimates with the spacetime expansion to control the solution and suppress the nonlinear blow-up mechanism. To achieve this, we commute the Laplace-Beltrami operator with a boosts-free subset of the Poincaré algebra and employ Klainerman-Sideris types of inequalities. Our strategy is general and is developed to handle the non-stationary nature of FLRW spacetimes. While we focus solely on this Fritz John type of equation, which serves as a prototype to study blow-up of non-linear waves, our approach provides a rigorous proof of the regularizing effects of spacetime expansion and can be exploited for a wider range of applications and nonlinearities.

2603.01983 2026-03-27 math.AP

Analysis of the steady solutions of the Fisher's infinitesimal model; a Hilbertian approach

M Hillairet, S Mirrahimi

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We provide an asymptotic analysis of a nonlinear integro-differential equation which describes the evolutionary dynamics of a population which reproduces sexually and which is subject to selection and competition. The sexual reproduction is modeled via a nonlinear integral term, known as the Fisher's 'infinitesimal model'. We consider a small segregational variance regime, where a parameter in the infinitesimal model, which measures the deviation between the trait of the offspring and the mean parental trait, is small with respect to the selection variance. In this regime, we characterize the steady states of the problem and analyze their stability. Our method relies on a spectral analysis involving Hermite polynomials, highlighting the specific structure of the nonlinear reproduction term. We expect that the framework developed in this article will contribute to progress on several related problems that were out of reach with previous methods.

2603.01127 2026-03-27 math.SP math.GT math.PR

Eigenvalue rigidity of hyperbolic surfaces in the random cover model

Elena Kim, Zhongkai Tao

Comments 29 pages. Comments are welcome! v2: Added a new section on eigenfunction estimates

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Let $X$ be a compact connected orientable hyperbolic surface and let $X_n$ be a degree $n$ random cover. We show that, with high probability, the distribution of eigenvalues of the Laplacian on $X_n$ converges to the spectral measure of the hyperbolic plane with polynomially decaying error. This is analogous to the eigenvalue rigidity property for graphs of Huang--Yau [arXiv:2102.00963] and improves the logarithmic bound of Monk [arXiv:2002.00869]. We also obtain a polynomial improvement on the $L^{\infty}$ bound of the eigenfunctions. Our proof relies on the Selberg trace formula and a variant of the polynomial method.

2602.24242 2026-03-27 cond-mat.stat-mech cond-mat.quant-gas cond-mat.str-el nlin.SI

Anomalous hydrodynamic fluctuations in the quantum XXZ spin chain

Takato Yoshimura, Žiga Krajnik, Alvise Bastianello, Enej Ilievski

Comments v1:9+2 pages, 3 figures. v2: typos corrected and references added

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英文摘要

The quantum XXZ spin-1/2 chain features non-Gaussian spin current fluctuations in the regime of easy-axis anisotropy. Using ballistic macroscopic fluctuation theory, we derive the exact probability distribution of typical spin-current fluctuations in thermal equilibrium. The obtained nested Gaussian distribution is fully characterized by its variance which we analytically relate to the spin diffusion constant and static spin susceptibility, and compare with numerical simulations. By unveiling how the same mechanism which leads to anomalous charge current fluctuations in single-file systems manifests itself in the XXZ chain, our approach establishes the universal hydrodynamic origin of the observed anomalous fluctuations.

2602.22262 2026-03-27 gr-qc astro-ph.HE hep-th

Conformal symmetry in force-free electrodynamics

Huiquan Li, Jianyong Wang

Comments 10 pages, 0 figure

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英文摘要

It is shown that conformal symmetry exists in force-free electrodynamics (FFE) in Minkowski spacetime, a foundational framework for describing magnetospheres around astronomical objects. In force-free magnetospheres, charges are constrained to move along magnetic field lines and experience zero Lorentz force, due to the everywhere perpendicular orientation of electric and magnetic fields. However, a general angle-preserving conformal mapping of force-free fields does not necessarily produce another physically admissible force-free configuration when sources are present. In this work, we demonstrate that such invariance can nevertheless arise for certain choices of the free functions. Specifically, the governing stream equation is shown to be invariant under Möbius transformations. This symmetry reveals a structural linkage between known solutions and, notably, maps the region inside a magnetospheric horizon (the lightsurface) of one solution to the exterior of its dual counterpart, and vice versa.

2602.22095 2026-03-27 quant-ph

On the emergence of quantum mechanics from stochastic processes

Jason Doukas

Comments 31 pages, 1 figure. v2: corrected typos and expanded the discussion in Section 6

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英文摘要

The stochastic--quantum correspondence reinterprets quantum dynamics as arising from an underlying stochastic process on a configuration space. We generalize the correspondence by lifting an arbitrary stochastic kernel $Γ$ in finite dimension to a map $ϕ$ on $B(\mathcal H)$, formulating the associated lift-compatibility relation, and giving an explicit dictionary between $Γ$ and CPTP (Kraus) maps. We isolate Chapman--Kolmogorov divisibility of the lifted family as the decisive additional constraint: when a CK-consistent CPTP family exists, the lift admits a Lindblad master equation form. In this picture, off-diagonal (phase) degrees of freedom act as a compressed carrier of history dependence not fixed by transition kernels alone; conversely, the apparent emergence of quantum phase information from a phase-blind stochastic description is explained as a memory effect. Finally, we state and prove a divisibility criterion for the underlying stochastic kernels, expressed as a condition involving divisibility of the lifted map together with a diagonality requirement on the density operator.

2602.20061 2026-03-27 cs.CR

Can You Tell It's AI? Human Perception of Synthetic Voices in Vishing Scenarios

Zoha Hayat Bhatti, Bakhtawar Ahtisham, Seemal Tausif, Niklas George, Nida ul Habib Bajwa, Mobin Javed

Comments Withdrawn at the request of the authors pending further revision

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英文摘要

Large Language Models and commercial speech synthesis systems now enable highly realistic AI-generated voice scams (vishing), raising urgent concerns about deception at scale. Yet it remains unclear whether individuals can reliably distinguish AI-generated speech from human-recorded voices in realistic scam contexts and what perceptual strategies underlie their judgments. We conducted a controlled online study in which 22 participants evaluated 16 vishing-style audio clips (8 AI-generated, 8 human-recorded) and classified each as human or AI while reporting confidence. Participants performed poorly: mean accuracy was 37.5%, below chance in a binary classification task. At the stimulus level, misclassification was bidirectional: 75% of AI-generated clips were majority-labeled as human, while 62.5% of human-recorded clips were majority-labeled as AI. Signal Detection Theory analysis revealed near-zero discriminability (d' approx 0), indicating inability to reliably distinguish synthetic from human voices rather than simple response bias. Qualitative analysis of 315 coded excerpts revealed reliance on paralinguistic and emotional heuristics, including pauses, filler words, vocal variability, cadence, and emotional expressiveness. However, these surface-level cues traditionally associated with human authenticity were frequently replicated by AI-generated samples. Misclassifications were often accompanied by moderate to high confidence, suggesting perceptual miscalibration rather than uncertainty. Together, our findings demonstrate that authenticity judgments based on vocal heuristics are unreliable in contemporary vishing scenarios. We discuss implications for security interventions, user education, and AI-mediated deception mitigation.

2602.17457 2026-03-27 math.AP

Construction of two-bubble blow-up solutions for the mass-critical gKdV equations

Yang Lan, Xu Yuan

Comments 72 pages, minor revisions

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英文摘要

For the mass-critical generalized Korteweg-de Vries equation, $$ \partial_{t}u+\partial_{x}\left( \partial_{x}^{2}u+u^{5}\right)=0,\quad (t,x)\in [0,\infty)\times \mathbb{R}.$$ We prove the existence of a global solution that blows up in infinite time and approaches the sum of two decoupled bubbles with opposite signs. The proof is inspired by the techniques developed for the two-dimensional mass-critical NLS equation in a similar context by Martel-Raphaël [37]. The main difficulty originates from the fact that the unstable directions related to scaling are excited by the nonlinear interactions. To overcome this difficulty, a refined approximate solution that involves some non-localized profiles is needed. In particular, a sharp understanding for the interactions between solitons and such profiles is also required.

2602.14618 2026-03-27 math.PR math-ph math.DS math.MP

Finitary coding and Gaussian concentration for random fields

J. -R. Chazottes, S. Gallo, D. Takahashi

Comments 36 pages, 1 figure. The presentation has been streamlined: the two sharpness results are now in the main section. No changes have been made to the mathematics aside from the correction of a few typos

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英文摘要

We study Gaussian concentration inequalities for random fields obtained as finitary codings of i.i.d.\ fields, linking concentration properties to coding structure. A finitary coding represents a dependent field as a shift-equivariant image of an i.i.d.\ process, where each output depends on a finite but configuration-dependent portion of the input. Gaussian concentration corresponds to uniform sub-Gaussian bounds for local observables. Our main abstract result shows that Gaussian concentration is preserved under finitary codings with finite second moment of the coding volume. The proof relies on a refinement of the bounded-differences inequality, due to Talagrand and Marton, handling configuration-dependent influences. Under an additional structural assumption, satisfied in particular by coupling-from-the-past codings, a finite first moment suffices. These moment conditions are sharp. We apply these results to Gibbs measures, Markov random fields on $\mathbb Z^d$, and a broad class of one-dimensional processes. Using recent constructions of finitary codings, notably by Spinka and collaborators, we obtain sharp necessary and sufficient conditions for Gaussian concentration in classical lattice models, including the Ising, Potts, and random-cluster models: it holds if and only if the model lies in the full uniqueness regime, extending previous results beyond strict subregimes. In one dimension, we treat processes with possibly unbounded memory. For countable-state Markov chains, we obtain equivalent characterizations in terms of geometric ergodicity, exponential return-time tails, and finitary i.i.d.\ codings with exponential tails.