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2603.24205 2026-03-26 quant-ph

Mitigating Dynamic Crosstalk with Optimal Control

Matthias G. Krauss, Luise C. Butzke, Christiane P. Koch

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英文摘要

The prevalence of quantum crosstalk is an important barrier to scaling frequency-addressable qubit architectures, with dynamic crosstalk being particularly difficult to detect and suppress. This form of crosstalk refers to unintended interactions driven by the gate control fields themselves. Here, we minimize dynamic crosstalk using quantum optimal control based on the perfect entangler spectrum, where spectral peaks signal unwanted entanglement with spectator qubits. Focusing on parametric gates in tunable coupler systems, we derive pulse shapes that eliminate dynamic crosstalk. Remarkably, only minimal pulse modifications are required to mitigate the form of crosstalk that is otherwise most difficult to predict. The ability to suppress dynamic crosstalk via the perfect entangler spectrum establishes a generalizable control principle for eliminating unwanted interactions in quantum hardware.

2603.24204 2026-03-26 cs.IR

SumRank: Aligning Summarization Models for Long-Document Listwise Reranking

Jincheng Feng, Wenhan Liu, Zhicheng Dou

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英文摘要

Large Language Models (LLMs) have demonstrated superior performance in listwise passage reranking task. However, directly applying them to rank long-form documents introduces both effectiveness and efficiency issues due to the substantially increased context length. To address this challenge, we propose a pointwise summarization model SumRank, aligned with downstream listwise reranking, to compress long-form documents into concise rank-aligned summaries before the final listwise reranking stage. To obtain our summarization model SumRank, we introduce a three-stage training pipeline comprising cold-start Supervised Fine-Tuning (SFT), specialized RL data construction, and rank-driven alignment via Reinforcement Learning. This paradigm aligns the SumRank with downstream ranking objectives to preserve relevance signals. We conduct extensive experiments on five benchmark datasets from the TREC Deep Learning tracks (TREC DL 19-23). Results show that our lightweight SumRank model achieves state-of-the-art (SOTA) ranking performance while significantly improving efficiency by reducing both summarization overhead and reranking complexity.

2603.24200 2026-03-26 hep-ph hep-ex hep-th

Magnetic-monopole resummation justifies perturbatively calculated collider production cross sections

Jean Alexandre, Nick E. Mavromatos, Vasiliki A. Mitsou, Emanuela Musumeci

Comments 32 pages, 13 figures, REVTeX

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英文摘要

A one-loop resummation scheme, inspired by Dyson-Schwinger (DS) formalism of strongly coupled quantum field theories, is applied to spin-1/2 magnetic monopoles (MMs), in the context of an effective field theory (EFT), invariant under the gauge group U(1)_em x U(1)', where U(1)' is a dual strongly coupled Abelian interaction, associated with a "dark photon". An ultra-violet fixed point structure is found in the resummed theory, which is purely non-perturbative, due to different boundary conditions of the resummation equations, compared to the weak coupling (perturbative) case. A self-consistent identification of the renormalized coupling of the MM to the electromagnetic photon in the fixed-point theory with the magnetic charge, compatible with the Dirac quantization condition, is made. This provides for the first time a formal justification of the use of tree-level Drell-Yan and photon-fusion MM production processes in collider searches, and of the corresponding cross sections and MM mass bounds thereof. The latter provide a means to constrain the resummed-EFT parameters experimentally. The DS resummation applies here primarily to the case of elementary (structureless) MMs. However, this approach may also be applied to the last stage (collapse) of the formation of composite MM pairs at colliders, in case they behave as quantum excitations, with their core radius comparable to the Compton wavelength, thereby avoiding the extreme suppression of their production.

2603.24199 2026-03-26 cs.PL

Adapting the MVVM pattern to C++ frontends and Agda-based backends

Viktor Csimma

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英文摘要

Using agda2hs and ad-hoc Haskell FFI bindings, writing Qt applications in C++ with Agda- or Haskell-based backends (possibly including correctness proofs) is already possible. However, there was no repeatable methodology to do so, nor to use \emph{arbitrary} Haskell built-in libraries in Agda code. We present a well-documented, general methodology to address this, applying the ideas of the Model-View-ViewModel architecture to models implemented in functional languages. This is augmented by a software development kit providing easy installation and automated compilation. For obstacles arising, we provide solutions and ideas that are novel contributions by themselves. We describe and compare solutions for using arbitrary Haskell built-ins in Agda code, highlighting their advantages and disadvantages. Also, for user interruption, we present a new Haskell future design that, to the best of our knowledge, is the first to provide for arbitrary interruption and the first to provide for interruption via direct FFI calls from C and C++. Finally, we prove with benchmarks that the agda2hs compiler at the base of our methodology is viable when compared to other solutions, specifically to the OCaml extraction feature of Rocq and the default MAlonzo backend of Agda.

2603.24195 2026-03-26 math.DG gr-qc math-ph math.MG math.MP

Comparison theory for Lipschitz spacetimes

Mathias Braun, Marta Sálamo Candal

Comments 52 pages. Comments welcome

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英文摘要

We prove a globally hyperbolic spacetime with locally Lipschitz continuous metric and timelike distributional Ricci curvature bounded from below obeys the timelike measure contraction property. The remarkable class of examples of spacetimes that are covered by this result includes impulsive gravity waves, thin shells, and matched spacetimes. As applications, we get new comparison theorems for Lipschitz spacetimes in sharp form: d'Alembert, timelike Brunn-Minkowski, and timelike Bishop-Gromov. Under appropriate nonbranching assumptions (conjectured to hold in even lower regularity), our results also yield the timelike curvature-dimension condition, a volume incompleteness theorem, as well as exact representation formulas and sharp comparison estimates for d'Alembertians of Lorentz distance functions from general spacelike submanifolds. Moreover, we establish the sharp timelike Bonnet--Myers inequality ad hoc using the localization technique from convex geometry. Alongside, we prove a timelike diameter estimate for spacetimes whose timelike Ricci curvature is positive up to a "small" deviation (in an $L^p$-sense). This adapts prior theorems for Riemannian manifolds by Petersen-Sprouse and Aubry to Lorentzian geometry, a transition the former two anticipated almost 30 years ago.

2603.24192 2026-03-26 math.AP math.OC

$Γ$-convergence of convolution-type functionals for free discontinuity problems

Giuseppe Cosma Brusca, Davide Donati, Sergio Scalabrino, Chiara Trifone, Edoardo Voglino

Comments 38 pages

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英文摘要

We prove compactness with respect to $Γ$-convergence for a general class of non-local energies modelled after the ones considered in [Gobbino, CPAM (1998)]. We give an integral representation result for the limits, which are free discontinuity functionals defined on the space of generalised special functions of bounded variation. We then characterise the bulk and surface energy densities of the obtained limits by means of minimisation problems on small cubes for the approximating energies.

2603.24191 2026-03-26 cs.CY cs.SE

Integrating Mental Health, Well-Being, and Sustainability into Software Engineering Education

Isabella Graßl, Birgit Penzenstadler

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英文摘要

Mental health and well-being are major concerns in higher education and professional fields such as software engineering, yet are often overlooked in curricula. This paper describes our approach to include mental health, well-being, and sustainability in software engineering education in two ways: (1) well-being-focused software projects that ask students to design technical solutions or research addressing mental health and sustainability or societal challenges, and (2) brief classroom interventions such as short reflective discussions and team-building activities. We argue that this combination can help students see software engineering more broadly while creating healthier learning environments. Our analysis of reflections from 60 students found several positive outcomes: students gained a more human-centred perspective, had more team discussions about mental health, and began to see well-being as inspiration for using software to benefit society and individuals rather than merely as a technical or business tool. By combining technical skills with awareness of well-being, we argue that software engineering education can prepare future developers to be both skilled programmers and responsible professionals who care about human well-being.

2603.24190 2026-03-26 cond-mat.stat-mech econ.GN nlin.CD physics.soc-ph q-fin.EC q-fin.ST

Dynamical thermalization and turbulence in social stratification models

Klaus M. Frahm, Dima L. Shepelyansky

Comments 16 pages, 12 figures

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英文摘要

We study the nonlinear chaotic dynamics in a system of linear oscillators coupled by social network links with an additional stratification of oscillator energies, or frequencies, and supplementary nonlinear interactions. It is argued that this system can be viewed as a model of social stratification in a society with nonlinear interacting agents with energies playing a role of wealth states of society. The Hamiltonian evolution is characterized by two integrals of motion being energy and probability norm. Above a certain chaos border the chaotic dynamics leads to dynamical thermalization with the Rayleigh-Jeans (RJ) distribution over states with given energy or wealth. At low energies, this distribution has RJ condensation of norm at low energy modes. We point out a similarity of this condensation with the wealth inequality in the world countries where about a half of population owns only a couple of percent of the total wealth. In the presence of energy pumping and absorption, the system reveals features of the Kolmogorov-Zakharov turbulence of nonlinear waves.

2603.24189 2026-03-26 math.NA cs.NA math-ph math.MP

Volume Term Adaptivity for Discontinuous Galerkin Schemes

Daniel Doehring, Jesse Chan, Hendrik Ranocha, Michael Schlottke-Lakemper, Manuel Torrilhon, Gregor Gassner

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We introduce the concept of volume term adaptivity for high-order discontinuous Galerkin (DG) schemes solving time-dependent partial differential equations. Termed v-adaptivity, we present a novel general approach that exchanges the discretization of the volume contribution of the DG scheme at every Runge-Kutta stage based on suitable indicators. Depending on whether robustness or efficiency is the main concern, different adaptation strategies can be chosen. Precisely, the weak form volume term discretization is used instead of the entropy-conserving flux-differencing volume integral whenever the former produces more entropy than the latter, resulting in an entropy-stable scheme. Conversely, if increasing the efficiency is the main objective, the weak form volume integral may be employed as long as it does not increase entropy beyond a certain threshold or cause instabilities. Thus, depending on the choice of the indicator, the v-adaptive DG scheme improves robustness, efficiency and approximation quality compared to schemes with a uniform volume term discretization. We thoroughly verify the accuracy, linear stability, and entropy-admissibility of the v-adaptive DG scheme before applying it to various compressible flow problems in two and three dimensions.

2603.24188 2026-03-26 math.RA math.RT

Hereditarily and Super Bassian Modules over Certain Rings

Peter Vassilev Danchev, Truong Cong Quynh, Jan Žemlička

Comments 12 pages

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We characterize in certain basic cases when a module over a ring is either {\it hereditarily Bassian} or {\it super Bassian} in the sense that either each its proper submodule is Bassian or, respectively, each its proper epimorphic image is Bassian. We prove several structural criteria for both hereditarily Bassian and super Bassian modules over non-primitive Dedekind prime rings, and in particular Dedekind domains. Over these rings, we establish that a singular module is super Bassian exactly when it is Bassian, which is true if and only if it is Bassian. In addition, for an arbitrary (not necessarily singular) module over a non-primitive Dedekind prime ring, the property of being super Bassian curiously implies the property of being hereditary Bassian always. Our results somewhat continue and supply recent results due to Tuganbaev in Mathematics (2026) and Blacher in J. Algebra (2026).

2603.24185 2026-03-26 cond-mat.mtrl-sci

Tunable intersublattice exchange coupling drives magnetic evolution in Mn$_{3+x}$Ga$_{1-x}$C ($0 \le x \le 0.60$)

Dong-Hui Xu, Cong-Mian Zhen, Deng-Lu Hou, Li Ma, De-Wei Zhao, Guo-ke Li

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英文摘要

We investigate the magnetic and transport evolution in Mn$_{3+x}$Ga$_{1-x}$C ($0 \le x \le 0.60$), where Mn substitution at corner Ga sites induces lattice contraction and suppresses the antiferromagnetic order of Mn$_3$GaC. As $x$ increases, the magnetic ground state of the system undergoes a sequential transition from an antiferromagnetic state, via a canted ferrimagnetic state, to a robust ferrimagnetic state, accompanied by a surge in the magnetic ordering temperature. Saturation magnetic moments reaches a maximum of 3.63~$μ_{\mathrm{B}}$/f.u. at $x = 0.10$, whereas the topological Hall resistivity peaks at 1.47~$μΩ\cdot$cm for $x = 0.20$ before decreasing with further doping. First-principles calculations demonstrate a $\sim\!40^{\circ}$ canting of face-centered Mn moments at $x = 0.20$, signifying spin frustration, and an eventual antiparallel alignment of face-centered and corner-site Mn moments at higher $x$. These results reveal that intersublattice antiferromagnetic coupling governs the magnetic transformation and emergent transport phenomena, thus providing a microscopic foundation for designing high-ordering-temperature antiperovskites.

2603.24183 2026-03-26 cond-mat.stat-mech physics.comp-ph quant-ph

Digitally Optimized Initializations for Fast Thermodynamic Computing

Mattia Moroder, Felix C. Binder, John Goold

Comments 10 pages, 3 figures

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Thermodynamic computing harnesses the relaxation dynamics of physical systems to perform matrix operations. A key limitation of such approaches is the often long thermalization time required for the system to approach equilibrium with sufficient accuracy. Here, we introduce a hybrid digital-thermodynamic algorithm that substantially accelerates relaxation through optimized initializations inspired by the Mpemba effect. In the proposed scheme, a classical digital processor efficiently computes an initialization that suppresses slow relaxation modes, after which the physical system performs the remaining computation through its intrinsic relaxation dynamics. We focus on overdamped Langevin dynamics for quadratic energy landscapes, analyzing the spectral structure of the associated Fokker-Planck operator and identifying the corresponding optimal initial covariances. This yields a predictable reduction in thermalization time, determined by the spectrum of the encoded matrix. We derive analytic expressions for the resulting speedups and numerically analyze thermodynamic implementations of matrix inversion and determinant computation as concrete examples. Our results show that optimized initialization protocols provide a simple and broadly applicable route to accelerating thermodynamic computations.

2603.24182 2026-03-26 astro-ph.SR

SS Cygni: An analysis of quasi-periodic oscillations in the range of 0.25h to 8h

Ian D Sharp

Comments 12 pages, 6 figures

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Journal ref
BAA VSS Circular, 207, March 2026
英文摘要

Presented here is an analysis of over 66,000 magnitude measurements, made by the author, of the cataclysmic variable SS Cygni in two photometric filters (Cousins R and Johnson V). This large number of measurements, along with their cadence, is sufficient to analyse the light curve for quasi-periodic oscillations (QPOs) ranging from a few minutes to a few hours with the most frequently found QPOs having periods of 30 minutes (48 cycles/day). These QPOs occur predominantly during quiescent phases rather than outbursts, representing a previously understudied aspect of SS Cygni's variability.

2603.24180 2026-03-26 cs.IT eess.SP math.IT

RIS-Assisted D-MIMO for Energy-Efficient 6G Indoor Networks

Akshay Vayal Parambath, Jose Flordelis, Venkatesh Tentu, Charitha Madapatha, Fredrik Rusek, Erik Bengtsson, Tommy Svensson

Comments 6 pages, 5 figures, Accepted to the IEEE International Conference on Communications (ICC) 2026

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We propose an alternating optimization framework for maximizing energy efficiency (EE) in reconfigurable intelligent surface (RIS) assisted distributed MIMO (D-MIMO) systems under both coherent and non-coherent reception modes. The framework jointly optimizes access point (AP) power allocation and RIS phase configurations to improve EE under per-AP power and signal-to-interference-plus-noise ratio (SINR) constraints. Using majorization-minimization for power allocation together with per-element RIS adaptation, the framework achieves tractable optimization of this non-convex problem. Simulation results for indoor deployments with realistic power-consumption models show that the proposed scheme outperforms equal-power and random-scatterer baselines, with clear EE gains. We evaluate the performance of both reception modes and quantify the impact of RIS phase-shift optimization, RIS controller architectures (centralized vs. per-RIS control), and RIS size, providing design insights for practical RIS-assisted D-MIMO deployments in future 6G networks.

2603.24179 2026-03-26 astro-ph.CO gr-qc

Perturbative and numerical study of nonlinear relativistic effects in weak lensing

Matteo Magi, Francesca Lepori, Julian Adamek

Comments 50 pages, 8 figures. Code available on GitHub

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英文摘要

The standard weak lensing formalism assumes that the lensing map relating the observed image of a source to its intrinsic shape depends only on the deflection angle. We show that this description is incomplete beyond linear perturbation theory, even when only scalar perturbations are present at first order. Using the Jacobi map formalism, we derive expressions for the rotation field, shear B-modes, and their angular power spectra at second order in relativistic perturbation theory. In the standard formalism, rotation and shear B-modes share the same spectrum, however, this degeneracy is broken once the parallel transport of the Sachs basis is consistently taken into account. We quantify this correction numerically, finding a difference of about $5\%$ on large angular scales $\ell \sim 5$ for sources at redshift $z_\mathrm{s} = 0.5$. We also investigate frame-dragging effects, which are usually neglected in weak lensing. We present the first analytical derivation of the corresponding impact on the angular power spectrum of shear B-modes and show that it becomes the dominant contribution on scales $\ell \lesssim 10$. While both Sachs-basis rotation and frame dragging significantly affect shear B-modes on large scales, their effect on the observed galaxy ellipticity is of order $1\%$, making these nonlinear relativistic corrections challenging to detect in practice. Our results are supported by relativistic simulations of weak lensing observables, including the first numerical study of frame dragging in the power spectra of the lensing convergence and cosmic shear.

2603.24178 2026-03-26 cond-mat.mtrl-sci

The domain-wall/metal-electrode injection barrier in lithium niobate: Which electrical transport model fits best?

Manuel Zahn, Elke Beyreuther, Iuliia Kiseleva, Julius Ratzenberger, Michael Rüsing, Lukas M. Eng

Comments 13 pages, 5 figures, with appended Supplemental Material (9 pages, 5 figures)

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英文摘要

The comprehensive description of both the electrical transport along conductive domain walls (CDWs) in lithium niobate (LNO) single crystals and the charge injection at the interfacing metal electrodes, emerged to be a complex challenge. Recently, a heuristic evaluation allowed to postulate the "R2D2" equivalent-circuit model (consisting of two parallel resistor-diode pairs) to appropriately match the DC current-voltage (I-V) characteristics. Here, we carefully revisit the interfacial electrical behavior, i.e., the diode part of the equivalent circuit model, since many more processes beyond the diode-related electron hopping transport (HT) assumed so far, may concurrently occur, such as thermionic emission (TE), Fowler-Nordheim tunneling (FNT), space-charge limited conduction (SCLC), and others more. The "R2D2" model thus needs to be generalized into an "R2X2" circuit model (with X = HT, TE, FNT, and others) to fit to the experimental data. Moreover, to double check for the best I-V curve fitting to the different theories, we apply a higher-harmonic DW current-contribution (HHCC) analysis, i.e., an AC I-V inspection, that allows us to discriminate between all these possible models with much higher precision than from pure DC I-V curve fitting. Both the AC and DC analysis reveal well consistent results, finally finding that the FNT model accounts best for the domain-wall/electrode junctions investigated here.

2603.24175 2026-03-26 math.CO

Nowhere-zero $3$-flows in Cayley graphs on solvable groups of twice square-free order

Milad Ahanjideh, István Kovács

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We verify Tutte's $3$-flow conjecture in the class of Cayley graphs on solvable groups of order $2n$, where $n$ is square-free. The proof relies on a new necessary and sufficient condition for a simple $5$-valent graph to admit a nowhere-zero $3$-flow in terms of a pseudoforest decomposition.

2603.24174 2026-03-26 astro-ph.IM physics.optics

Refractive multi-conjugate adaptive optics for wide-field atmospheric turbulence correction

Tommaso Furieri, Stefano Bonora

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Multi-Conjugate Adaptive Optics (MCAO) is essential for increasing the corrected Field-of-View (FoV) in astronomical imaging and potentially for free-space optical communications, particularly for small-aperture, transportable systems. We demonstrate the viability and performance of a Refractive-MCAO system utilizing a novel multi-actuator Deformable Lens (DL) as the wavefront correction element. Unlike conventional Deformable Mirrors (DMs), the transmissive nature of the DL simplifies the optical train, making it ideal for compact setups. Using a Shack-Hartmann Wavefront Sensor (SH-WFS) in conjunction with two DLs conjugated to different atmospheric layers, we achieved an extension of the isoplanatic patch up to three times the uncorrected atmospheric isoplanatic angle under moderate turbulence D/r0 = 2. We tested the MCAO system in a setup that emulates a free space optical communication for compact transportable system. In a double-channel, single-mode fiber coupling experiment we demonstrated the efficiency of this method.

2603.24173 2026-03-26 math.AG math.DS

On the dynamical degree of surjective endomorphisms

Ilya Karzhemanov

Comments 7 pages

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We establish a couple of dynamical properties of surjective rational maps $f: X \dashrightarrow X$ for smooth projective surfaces $X$. We also give a numerical characterization of regular $f$ in the case when $X$ is a del Pezzo surface. Some explicit constructions and calculations, related to the topological entropy of $f$, are provided.

2603.24169 2026-03-26 astro-ph.SR

ZIMPOL detects scattering polarization in He I D$_3$ during a solar flare

Francesco Vitali, Andrea Francesco Battaglia, Luca Belluzzi, Svetlana Berdyugina, Renzo Ramelli, Jiří Štěpán, Gioele Janett, Fabio Riva

Comments 9 pages, 6 figures, accepted for publication in A&A

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Spectropolarimetric observations of solar flares in the He I D$_3$ line at 5876 Å are extremely rare, and their diagnostic potential remains largely unexplored. We report the first unambiguous detection of linear polarization in He I D$_3$ during a solar flare. Using the high-precision ZIMPOL polarimeter at the IRSOL observatory in Locarno (Switzerland), we tracked the temporal evolution of the He I D$_3$ Stokes profiles throughout the M7 GOES-class flare that occurred on 3 May 2023 at 10:45 UT. We analyzed the time evolution of the maximum in linear polarization and the absorption depth of the intensity profile. Both the fractional linear polarization, which peaks at $6\times10^{-4}$, and the absorption depth increase rapidly before gradually decaying, with their maxima occurring approximately 5 minutes after the peaks in GOES X-ray flux and SDO/AIA 304 Å emission. From the evolving He I D$_3$ core position, we also derived the temporal evolution of the plasma bulk velocities. The intensity profiles exhibiting strong absorption seems to originate from the flare ribbons. The time evolution of all Stokes parameters in the 3 May 2023 event was driven by changes in ortho-helium density prompted by the different phases of the flare. Our analysis suggests that the observed He I D$_3$ linear polarization is likely not dominated by the theorized impact polarization, as it exhibits neither spatial correspondence with electron precipitation sites nor temporal synchronization with the impulsive phase. Instead, the signals are consistent with scattering polarization produced by anisotropic radiation pumping. We conclude that scattering polarization signal on the order of $0.01\%$ can be produced in the He I D$_3$ line during solar flares. This can provide constraints for flare models.

2603.24168 2026-03-26 gr-qc

Consistent Gauge Conditions for Dust-Shell Dynamics in Effective Quantum Gravity

Dongxue Qu, Cong Zhang

Comments 11 pages, 4 figures

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Previous analyses of shocks generated by shell-crossing singularities are affected by inappropriate gauge choices, and no systematic method is available for selecting a consistent gauge. In this work, we develop such a method for effective quantum gravity coupled to a dust shell. We illustrate it in classical general relativity and verify it numerically, with results in agreement with the Israel junction condition. We also show that gauges such as the Painlevé-Gullstrand and Schwarzschild ones are incompatible with the presence of a dust shell when imposed on the whole spatial slice. This explains the difficulties in previous treatments. The framework developed here provides a basis for studying shell-crossing singularities and shock dynamics in generally covariant effective black-hole models.

2603.24165 2026-03-26 math.FA

A non-vanishing property for tensor products of wavelets

Quentin Rible, Stéphane Seuret

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We prove that, given a wavelet $ψ$, it is possible to choose some multi-integers $(p_j=(p_{j,1},...,p_{j,d}))_{j \in \mathbb{Z}} \in \mathbb{Z}^d$ such that, for every $x=(x_1,...,x_d) \in \mathbb{R}^d$, for infinitely many integers $j$, the tensorized wavelet $\prod_{i=1}^d ψ(2^j x_i-p_{j,i})$ does not vanish at $x$. This non-vanishing property is essential for analyzing some generic regularity properties in certain Sobolev and Besov spaces. The proof relies on an assumption regarding the zeros of $ψ$, which we numerically verify for the first Daubechies wavelets.

2603.24164 2026-03-26 gr-qc hep-th

Phase Structure of Scalarized Black Holes in Einstein-Scalar-Gauss-Bonnet Gravity

Carlos Herdeiro, Hyat Huang, Jutta Kunz, Meng-Yun Lai, Eugen Radu, De-Cheng Zou

Comments 21 pages, 14 figures. Comments are welcome!

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英文摘要

We revisit scalarized black holes in Einstein-scalar-Gauss-Bonnet gravity and analyze the thermodynamic phase transition between the Schwarzschild solution of general relativity and scalarized black holes. Restricting to spherically symmetric configurations, we investigate several classes of scalar-Gauss-Bonnet coupling functions. For the simplest quadratic coupling that triggers spontaneous scalarization, the scalarized solutions are thermodynamically disfavored and no phase transition occurs. For an exponential coupling, the phase structure depends strongly on the coupling parameter, allowing for the absence of a transition, a continuous second-order transition, or a discontinuous first-order transition. For couplings leading to purely nonlinear scalarization, we find either a first-order transition or no transition. These results reveal a rich phase structure of scalarized black holes controlled by the scalar-Gauss-Bonnet coupling.

2603.24163 2026-03-26 math.AP math.OC

Density Measures

Moritz Schönherr, Friedemann Schuricht

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The paper treats density measures as typical examples of finitely additive measures in $\mathbb{R}^n$. We study their structure and derive basic properties. In addition, estimates for related integrals are provided. The results are applied to the precise representative of general integrable functions and then they are specialized to functions of bounded variation. Moreover, a new representation of the generalized gradients in the sense of Clarke is given for the finite dimensional case.

2603.24161 2026-03-26 math.NA cs.NA

Probabilistic Error Analysis of Limited-Precision Stochastic Rounding: Horner's Algorithm and Pairwise Summation

El-Mehdi El Arar, Massimiliano Fasi, Silviu-Ioan Filip, Mantas Mikaitis

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英文摘要

Stochastic rounding (SR) is a probabilistic rounding mode that mitigates errors in large-scale numerical computations, especially when prone to stagnation effects. Beyond numerical analysis, SR has shown significant benefits in practical applications such as deep learning and climate modelling. The definition of classical SR requires that results of arithmetic operations are known with infinite precision. This is often not possible, and when it is, the resulting hardware implementation can become prohibitively expensive in terms of energy, area, and latency. A more practical alternative is limited-precision SR, which only requires that the outputs of arithmetic operations are available in higher, finite, precision. We extend previous work on limited-precision SR presented in [El Arar et al., SIAM J. Sci. Comput. 47(5) (2025), B1227-B1249], which developed a framework to evaluate the trade-off between accuracy and hardware resource cost in SR implementations. Within this framework, we study the Horner algorithm and pairwise summation, providing both theoretical insights and practical experiments in these settings when using limited-precision SR.

2603.24159 2026-03-26 astro-ph.HE astro-ph.GA

Simultaneous Multi-band Optical Follow-up Observations of a Gamma-Ray Flare in BL Lacertae

X. Chang, D. R. Xiong, Chenxu Liu, J. R. Xu, G. Bhatta, T. F. Yi, J. Zhang, Y. Pan, X. Z. Zou, X. L. Chen, Y. P. Yang, J. H. Zhang, X. K. Liu, Y. Fang, G. W. Du, T. Wang, X. F. Zhu, Y. L. Gong, Z. X. Wang, X. W. Liu

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On $2024$ October $5$, BL Lacertae ($2200+420$) experienced one of its brightest gamma-ray flares. We conducted simultaneous follow-up observations in the $u$, $v$, $g$, $r$, $i$, and $z$ bands from $2024$ October $17$ to November $21$ using the Mephisto telescope and its two $50$ cm twin auxiliary photometric telescopes of Yunnan University. Intraday variability (IDV) was detected in the $g$, $r$, $i$, and $z$ bands. The IDV duty cycle increased with observing frequency across these bands. The shortest variability time-scale, derived from auto-correlation analysis, constrains the upper limit of the black hole mass to be $M_{\bullet} \lesssim 10^{8.29} M_{\odot}$ assuming a Kerr black hole, and $M_{\bullet} \lesssim 10^{8.77} M_{\odot}$ assuming a Schwarzschild black hole. The emission region responsible for the observed variability has a size of $R \le 3.51 \times 10^{14}$ cm and is located at a distance of $R_H \le 2.83 \times 10^{15}$ cm from the central supermassive black hole. This distance is approximately three orders of magnitude smaller than the typical radius of the broad-line region, indicating that the emission region lies well within it. A general bluer-when-brighter (BWB) trend was detected on intraday time-scales, suggesting that shock-accelerated relativistic electrons enhance the high-energy particle population, leading to spectral hardening. A potential quasi-periodic oscillation (QPO) with a period of $\sim 100.77$ minutes was detected with $>99.99$ per cent confidence, consistent with predictions from the magnetic reconnection model. These observed optical intraday variabilities and colour variations of BL Lacertae can be well explained by the turbulent jet model.

2603.23285 2026-03-26 physics.plasm-ph physics.acc-ph physics.comp-ph physics.optics

Optical modelling of shaped laser pulses in plasma

Igor A. Andriyash, Cedric Thaury

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This work provides a brief review of the numerical methods for modelling the optical propagation of an ultrashort, intense laser pulse in plasmas and ionizable gases. These methods are implemented in an open-source simulation toolkit Axiprop, which is now actively used for design studies in the context of laser plasma acceleration of electrons (LPA). We present two examples of such studies: optical plasma waveguide generation, and phase-locked flying-focus LPA. These tools enable the identification of complex effects impacting both energy deposition during waveguide formation, and the pulse propagation dynamics that governs wakefield structure, ultimately determining the properties of the accelerated electron bunches. The developed tools and presented simulation designs are relevant to experiments on laser plasma interactions at modern high power laser facilities.

2603.23243 2026-03-26 math.QA

Shuffle algebra realizations for restricted Yangians

Hao Chang, Hongmei Hu, Yue Hu

Comments 18 pages, comments are welcome!

详情
英文摘要

We study the shuffle algebra realization of the positive subalgebra $Y_n^{>}(\mathbb{k})$ of the Yangian associated to $\mathfrak{sl}_n$ over an algebraically closed field $\mathbb{k}$ of characteristic $p>2$. In contrast to the characteristic zero case, the natural homomorphism from $Y_n^{>}(\mathbb{k})$ to the modular shuffle algebra $W^{(n)}(\mathbb{k})$ is not an isomorphism. We determine its kernel and image, showing that the kernel is precisely the ideal generated by the $p$-center of $Y_n^{>}(\mathbb{k})$, while the image consists of elements satisfying an additional wheel condition related to the characteristic $p$, thus providing a shuffle algebra realization for the restricted Yangian $Y_n^{>,[p]}$. The proof relies on the specialization maps approach and the construction of the small Yangian $\bar{y}^{>}_n(\mathbb{k})$, obtained by the reduction modulo $p$ method from an integral form $\mathbf{Y}_n^>$ of the Yangian $Y_n^{>}$ associated to $\mathfrak{sl}_n$ over $\mathbb{C}$.

2603.23151 2026-03-26 math.AP

Exponential Decay for a Boundary-Controlled Nonlinear Parabolic Reactor Model

Yevgeniia Yevgenieva, Alexander Zuyev, Christophe Prieur, Peter Benner

Comments This work has been submitted to the IEEE for possible publication

详情
英文摘要

We study an axial dispersion tubular reactor model governed by a nonlinear parabolic equation with Robin-type boundary conditions and boundary feedback control. We derive sufficient conditions for the exponential stability of the steady-state solution of the closed-loop system and provide an explicit estimate of the decay rate. In addition, numerical simulations are presented to illustrate the sharpness of the obtained decay rate for different choices of the feedback gain parameter.

2603.23078 2026-03-26 astro-ph.IM physics.atom-ph

A High-frequency Geodetic VLBI Experiment for Optical Clock Comparison

Monia Negusini, Myoung-Sun Heo, Cecilia Clivati, Shuangjing Xu, Roberto Ricci, Taehyun Jung, Buseung Cho, Matteo Stagni, Claudio Bortolotti, Giuseppe Maccaferri, Federico Perini, Mauro Roma, Do-Young Byun, Do-Heung Je, Marco Pizzocaro, Davide Calonico, Elena Cantoni, Giancarlo Cerretto, Stefano Condio, Giovanni A. Costanzo, Simone Donadello, Irene Goti, Michele Gozzelino, Alberto Mura, Filippo Levi, Matias Risaro, Huidong Kim, Won-Kyu Lee, Chang Yong Park, Dai-Hyuk Yu, Young Kyu Lee, Joon Hyo Rhee, Chanjin Park, Minseong Lee, Hyo Ryoung Kim, Sung-Moon Yoo, Jungho Cho, Jongsoo Kim, Sang-Oh Yi, Ha Su Yoon, Pablo de Vicente, Javier González, Cristina García Miró

Comments 12 pages, 3 figures

详情
Journal ref
PASP 138 024504 (2026)
英文摘要

An intercontinental metrological clock comparison between Italy and the Republic of Korea was performed by means of geodetic K-band VLBI observations. The comparison involved the hydrogen masers (H-masers) used at Medicina and Sejong radio telescopes. The same clocks were simultaneously compared by a satellite link and by high-precision optical clocks maintained at the National Metrology Institutes, KRISS in Korea and INRIM in Italy, and delivered to VLBI antennas via optical fiber. The H-masers frequency difference was estimated by extrapolating the clock rate from VLBI data using two geodetic VLBI software. This was subsequently compared with clock differences derived by satellite link and by local optical clocks. Results obtained with different approaches were in agreement at the level of $10^{-15}$ s/s. This pilot study demonstrates that standard high-frequency (K-band) geodetic VLBI campaigns could be a viable approach to conduct intercontinental clock comparisons, now only possible via satellite links. This uncertainty can be reduced thanks to the planned installation of new-generation, broadband, high-frequency receivers on the involved telescopes. K/Q/W-band geodetic observations will allow an improvement of the accuracy of the resulting group delays through broad bandwidth synthesis from 20 to 100 GHz. Furthermore, the Frequency Phase Transfer (FPT) method will also be explored together with the use of PCAL systems installed at the radio telescopes to improve phase stability and thus allow a better estimation of the station clock parameters.