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2507.19681 2026-04-13 astro-ph.SR

Revealing Flare Energetics and Dynamics with SDO EVE Solar Extreme Ultraviolet Spectral Irradiance Observations

Thomas N. Woods, Phillip C. Chamberlin, Andrew Jones, James P. Mason, Liying Qian, Harry P. Warren, Don Woodraska, Rita Borelli, Francis G. Eparvier, Gabi Gonzalez

Comments Manuscript is in press with Solar Physics (April 2026)

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英文摘要

NASA's Solar Dynamics Observatory (SDO) Extreme-ultraviolet Variability Experiment (EVE) has been making solar full-disk extreme ultraviolet (EUV) spectral measurements since 2010 over the spectral range of 6nm to 106nm with 0.1nm spectral resolution and with 10-60sec cadence. A primary motivation for EVE's solar EUV irradiance observations is to provide the important energy input for various studies of Earth's upper atmosphere. For example, the solar EUV creates the ionosphere, heats the thermosphere, and drives photochemistry in Earth's upper atmosphere. In addition, EVE's observations have been a treasure trove for solar EUV flare spectra. While EVE measures the full-disk spectra, the flare spectrum is easily determined as the EVE spectrum minus the pre-flare spectrum, as long as only one flare event is happening at a time. These EVE flare observations provide EUV variability that have been used to study flare phases (including the discovery of the EUV Late Phase flare class), flare energetics (plasma temperature variations), corona heating (plasma abundance changes that support nano-flare heating mechanism), flare dynamics (downwelling and upwelling plasma flows during flares from Doppler shifts), and coronal mass ejections (CME) energetics (CME mass and velocity derived from coronal dimming in some EUV lines). We also introduce a new EVE data product called the EVE Level 4 Lines data product, which provides line profile-fit results for intensity, wavelength shift, and line width for 70 emission features. These emission features are from the chromosphere, transition region, and corona, and so Doppler measurements of those lines can reveal important plasma dynamical behavior during a flare's impulsive phase and gradual phase. With over 10,000 flares detected in the EVE observations, there is still much to study and to learn about solar flare physics using EVE solar EUV spectra.

2507.14977 2026-04-13 cond-mat.mes-hall quant-ph

Potential barriers are nearly-ideal quantum thermoelectrics at finite power output

Chaimae Chrirou, Abderrahim El Allati, Robert S Whitney

Comments 13 pages & 6 figures. This is the final author version of this paper (to appear in Phys. Rev. B)

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Journal ref
Phys. Rev. B 113, 155304 (2026)
英文摘要

Quantum thermodynamics defines the ideal quantum thermoelectric, with maximum possible efficiency at finite power output. However, such an ideal thermoelectric is challenging to implement experimentally. Instead, here we consider two types of thermoelectrics regularly implemented in experiments: (i) finite-height potential barriers or quantum point contacts, and (ii) double-barrier structures or single-level quantum dots. We model them with Landauer scattering theory as (i) step transmissions and(ii) Lorentzian transmissions, respectively. We optimize their thermodynamic efficiency for any given power output, when they are used as thermoelectric heat engines or refrigerators. The Lorentzian's efficiency is excellent at vanishing power, but we find that it is poor at the finite powers of practical interest. In contrast, the step transmission is remarkably close to ideal efficiency (typically within 15\%) at all power outputs. The step transmission is also close to ideal in the presence of phonons and other heat leaks, for which the Lorentzian performs very poorly. Thus, a simple nanoscale thermoelectric - made with a potential barrier or quantum point contact - is almost as efficient as an ideal thermoelectric.

2507.12120 2026-04-13 astro-ph.GA astro-ph.CO

No evidence for Keplerian taper of far-out galactic rotation

Adriana Bariego-Quintana, Felipe J. Llanes-Estrada

Comments 20 pages, 7 figures Revised according to referee observations

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英文摘要

We present a statistical analysis of the 175 SPARC galactic rotation curves to test the hypothesis of whether the Keplerian velocity tapering at large radii ($V(r)\propto 1/\sqrt{r}$) germane to a convergent mass distribution in typical spherical halo models agrees with observational data. The null hypothesis is Rubin's flat-rotation curve, $V(r)=\text{constant}$ -such as can be obtained from a spherical, isothermal-like density profile, or alternatively with a very prolate halo-. To decide whether we adopt the null (Rubin behaviour) or alternative (Keplerian behaviour) hypothesis, we evaluate the derivative in each galaxy of $V(r)$ with its last data points. The test is model independent inasmuch we are testing for the \emph{slope} of the dark matter rotation curve, whether it is or not compatible with zero. We conclude that the data is presently compatible with the null hypothesis -no taper off, no decline of $V(r)$ is seen. Separately, beyond SPARC, our own Milky Way galaxy, for which recent data sets have been reported, does show clear $V(r)$ fall-off at the level of 20\%.

2507.07742 2026-04-13 quant-ph

Gate Freezing Method for Gradient-Free Variational Quantum Algorithms in Circuit Optimization

Joona Pankkonen, Lauri Ylinen, Matti Raasakka, Andrea Marchesin, Ilkka Tittonen

Comments 29 pages, 37 figures

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英文摘要

Parameterized quantum circuits (PQCs) are pivotal components of variational quantum algorithms (VQAs), which represent a promising pathway to quantum advantage in noisy intermediate-scale quantum (NISQ) devices. PQCs enable flexible encoding of quantum information through tunable quantum gates and have been successfully applied across domains such as quantum chemistry, combinatorial optimization, and quantum machine learning. Despite their potential, PQC performance on NISQ hardware is hindered by noise, decoherence, and the presence of barren plateaus, which can impede gradient-based optimization. To address these limitations, we propose novel methods for improving gradient-free optimizers Rotosolve, Fraxis, and FQS, incorporating information from previous parameter iterations. Our approach conserves computational resources by reallocating optimization efforts toward poorly optimized gates, leading to improved convergence. The experimental results demonstrate that our techniques consistently improve the performance of various optimizers, contributing to more robust and efficient PQC optimization.

2507.05474 2026-04-13 math.DS math.GR math.LO

Dense and comeager conjugacy classes in zero-dimensional dynamics

Michal Doucha, Julien Melleray, Todor Tsankov

Comments v2: The main change is generalizing Theorem 1.11 from free groups to infinite hyperbolic groups. 46 pages, 2 figures

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英文摘要

Given a countable group $G$, we initiate a systematic study of the Polish spaces of all minimal and topologically transitive actions of $G$ on the Cantor space by homeomorphisms, with a focus on the existence of comeager conjugacy classes in these spaces. We develop a general model-theoretic framework to study this and related questions, recovering on the way many existing results from the literature. A substantial part of the paper is devoted to actions of free groups. We show that in that case, there is a comeager conjugacy class in the space of minimal actions, as well as in the space of minimal, probability measure-preserving actions. The first one is the Fraïssé limit of all sofic minimal subshifts and the second, the universal profinite action. The case of the integers was already treated by Hochman and there the two actions coincide with the universal odometer. In the non-abelian case, they are substantially different and new techniques are required. In the opposite direction, if $G$ is an amenable group which is not finitely generated, we show that there is no comeager conjugacy class in the space of all actions, and if $G$ is locally finite, also in the space of minimal actions. Finally, we study the question of existence of a dense conjugacy class in the space of topologically transitive actions. We show that if $G$ is hyperbolic or virtually polycyclic, then such a dense conjugacy class exists iff $G$ is virtually cyclic, suggesting that the case of the integers may be exceptional.

2506.19735 2026-04-13 quant-ph

Quantum Resource Theories of Anyonic Entanglement

Wenhao Ye, Li You, Cheng-Qian Xu

Comments 6+14 pages, 2+1 figures

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Journal ref
Phys. Rev. Research 8, L022010 (2026)
英文摘要

As information carriers for fault-tolerant quantum computing, systems composed of anyons exhibit non-tensor product state spaces due to their distinctive fusion rules, leading to fundamentally different entanglement properties from conventional quantum systems. However, a quantitative characterization of entanglement for general anyonic states remains elusive. In this Letter, within the framework of resource theory, we propose three measures that quantify total entanglement, conventional entanglement, and anyonic charge entanglement (ACE), respectively. We demonstrate that total entanglement can be decomposed into conventional entanglement and ACE, revealing distinct entanglement structures in anyonic systems compared to those in conventional quantum systems. We further illustrate a geometric interpretation of our ACE measure and establish its equivalence to a previously proposed probe of ACE, extending the known equivalence between the geometric interpretation and operational significance of bipartite correlations. Our work broadens the understanding of entanglement.

2506.18498 2026-04-13 cs.IT math.IT

A scalable estimator of higher-order information in complex dynamical systems

Alberto Liardi, George Blackburne, Hardik Rajpal, Fernando E. Rosas, Pedro A. M. Mediano

Comments 12 pages, 5 figures + appendix

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英文摘要

Our understanding of complex systems rests on our ability to characterise how they perform distributed computation and integrate information. Advances in information theory have introduced several quantities to describe complex information structures, where collective patterns of coordination emerge from higher-order (i.e. beyond-pairwise) interdependencies. Unfortunately, the use of these approaches to study large complex systems is severely hindered by the poor scalability of existing techniques. Moreover, there are relatively few measures specifically designed for multivariate time series data. Here we introduce a novel measure of information about macroscopic structures, termed M-information, which quantifies the higher-order integration of information in complex dynamical systems. We show that M-information can be calculated via a convex optimisation problem, and we derive a robust and efficient algorithm that scales gracefully with system size. Our analyses show that M-information is resilient to noise, indexes critical behaviour in artificial neuronal populations, and reflects states of consciousness and task performance in real-world macaque and mouse neuroimaging data. Furthermore, M-information can be incorporated into existing information decomposition frameworks to reveal a comprehensive taxonomy of information dynamics. Taken together, these results help us unravel collective computation in large complex systems.

2506.06857 2026-04-13 physics.optics cond-mat.mtrl-sci

Stress-driven photo-reconfiguration of surface microstructures via vectorial field-guided lithography

I Komang Januariyasa, Francesco Reda, Nikolai Liubimtsev, Pawan Patel, Cody Pedersen, Fabio Borbone, Marcella Salvatore, Marina Saphiannikova, David J. McGee, Stefano Luigi Oscurato

Comments Published version citation and DOI added on title page; 44 pages, 6 main figures, 11 supporting information figures

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Light Sci Appl 15, 194 (2026)
英文摘要

Pattern formation driven by mechanical stress plays a fundamental role in shaping structural organization in both natural and human-made systems. Using light as a vectorial stimulus may offer a powerful route to control stress-induced pattern formation in materials. However, achieving localized, programmable, and predictable control of individual microstructures via structured polarization fields has remained a major challenge. Here, we introduce vectorial field-guided lithography, a novel approach that leverages fully structured polarization fields as lithographic tools to enable the stress-driven reconfiguration of pre-patterned azopolymer microstructures with an unprecedented degree of flexibility, complexity, and diversity. By building on the Viscoplastic PhotoAlignment model, which describes the azopolymer deformation as stress response to structured light, we quantitatively demonstrate and predict complex surface architectures generated by programmable light-induced stress pathways using a digital polarization rotator implemented via a spatial light modulator. We model and experimentally achieve single-step formation of anisotropic, bent, and chiral microstructures from a single pre-patterned geometry. Our results reveal an exceptional control over local microstructure morphology and establish, for the first time, a comprehensive theoretical framework capable of quantitatively designing and fabricating target morphologies on azopolymers. This work moves beyond conventional intensity-based photopatterning and demonstrates that the full vectorial nature of light can dictate the mechanical reshaping of functional polymer surfaces, providing a new platform for the programmable design of complex micro-architectures with applications in photonics, microfluidics, and biology.

2506.04692 2026-04-13 math.LO

Weak, strong and mixed extensions of relations to spaces of ultrafilters

Leonardo Raffaello Maximilian Gasparro, Lorenzo Luperi Baglini

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The use of nonstandard methods to characterize properties of weak, strong and mixed extensions of congruences to ultrafilters has been the main topic of several recent papers. We show that similar methods can be used to characterize the extensions of arbitrary realtions and their interplay.

2505.24632 2026-04-13 cond-mat.mes-hall cond-mat.mtrl-sci

Weak localization as probe of spin-orbit-induced spin-split bands in bilayer graphene proximity coupled to WSe$_2$

E. Icking, F. Wörtche, A. W. Cummings, A. Wörtche, K. Watanabe, T. Taniguchi, C. Volk, B. Beschoten, C. Stampfer

Comments 7 pages, 4 figures

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Journal ref
Phys. Rev. Applied 25, 044028 (2026)
英文摘要

Proximity coupling of bilayer graphene (BLG) to transition metal dichalcogenides (TMDs) offers a promising route to engineer gate-tunable spin-orbit coupling (SOC) while preserving BLG's exceptional electronic properties. This tunability arises from the layer-asymmetric electronic structure of gapped BLG, where SOC acts predominantly on the layer in contact with the TMD. Here, we present high-quality BLG/WSe$_2$ devices with a proximity-induced SOC gap and excellent electrostatic control. Operating in a quasi-ballistic regime, our double-gated heterostructures allow to form gate-defined p-n-p cavities and show clear weak anti-localization (WAL) features consistent with Rashba-type SOC. At lower hole densities, a transition to weak localization (WL) is observed, signaling transport through a single spin-split valence band. These findings - in agreement with calculations - provide direct spectroscopic evidence of proximity-induced spin-split band in BLG and underscore the potential of BLG/TMD heterostructures for spintronics and spin-based quantum technologies.

2505.21210 2026-04-13 cond-mat.stat-mech cond-mat.other

Functional renormalization group approach to phonon modified criticality: anomalous dimension of strain and non-analytic corrections to Hooke's law

Max O. Hansen, Julia von Rothkirch, Peter Kopietz

Comments 21 pages, 13 figures

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Journal ref
Phys. Rev. E 112, 064101 (2025)
英文摘要

We study the interplay between critical isotropic elasticity and classical Ising criticality using a functional renormalization group (FRG) approach which is implemented such that the volume is fixed during the entire renormalization group flow. For dimensions slightly smaller than four we use a simple truncation of the FRG flow equations to recover the fixed points of the constrained Ising model: the Gaussian fixed point G, the Ising fixed point I, the renormalized Ising fixed point R, and the spherical fixed point S. We show that the fixed points R and S are both characterized by a finite anomalous dimension $y_{\ast}<0$ of strain fluctuations, implying that the energy dispersion of longitudinal acoustic phonons exhibits a non-analytic momentum dependence proportional to $k^{1-y_{\ast}/2}$ for small momentum $k$. We also derive and solve flow equations for the free energy at constant strain and compute stress-strain relations in the vicinity of the fixed points. As a result, we reaffirm that Ising criticality, controlled by the fixed point I, is preempted by a bulk instability. Beyond that, we find that the stress-strain relation at R and S remains linear to leading order (Hooke's law), as long as the interaction between strain and Ising fluctuations is sufficiently weak. However, the finite anomalous dimension of strain fluctuations $y_{\ast}$ gives rise to non-analytic corrections to Hooke's law.

2505.06119 2026-04-13 cs.DC quant-ph

Tensor-Parallel Emulation of Quantum Circuits with Block-Cyclic Distributed Matrix Product States

Jakub Adamski, Oliver Thomson Brown

Comments Substantially revised following reviewer feedback. Preparing for journal submission. Contains 17 pages and 17 figures

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英文摘要

Tensor networks establish an adaptable framework for the emulation of quantum circuits. By partitioning exponentially large registers and gates into smaller tensors, this unlocks fast transformations through tensor algebra, and grants fine control over memory, runtime and accuracy. Due to inherently lower spatial footprint, there is a gap in distributed-memory tensor network methods. While certain parallel techniques exist, they are usually limited to direct contraction and sampling problems, and a more general approach is needed for tensor representations like matrix product states (MPS), which efficiently approximate full quantum state evolution. In this study, we expand the MPS site tensors beyond local memory by introducing a tensor-parallel distribution scheme, where individual dense tensors are evenly scattered across a subset of indices. This is further facilitated by leveraging pivoted QR factorisation instead of slower singular value decomposition (SVD). We demonstrate the capabilities of our approach by approximately emulating the classically difficult Google's random circuit sampling (RCS) benchmark. The highest bond dimensions of 16,384 is reached, surpassing the accuracy of the state-of-the-art methods by three orders of magnitude on 32 nodes of ARCHER2. We also show how this helps advance experiments involving more practical quantum phase estimation circuits. Our approach has the potential to enhance numerous algorithms based on dense tensor networks, offering a scalable and naturally load-balanced distribution formula. It is also compatible with other types of parallelism, unlocking new opportunities to push the quantum-classical computational phase boundary.

2505.03364 2026-04-13 cs.HC

DroidRetriever: A Transparent and Steerable Automation System for Collaborative Mobile Information Seeking

Yiheng Bian, Yunpeng Song, Guiyu Ma, Rongrong Zhu, Zhongmin Cai

Comments 24 pages, 8 figures. Accepted at CHI 2026 (ACM Conference on Human Factors in Computing Systems), Barcelona, Spain, April 2026

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Information seeking on mobile devices is often fragmented, trapping users in repetitive cycles of context switching and data re-entry, which increases cognitive load and disrupts workflow. Existing mobile agents provide limited cross-source integration and are largely opaque, presenting progress as a linear feed with few opportunities to intervene, steer, or take control. We present DroidRetriever, a transparent, steerable system for cross-source mobile information seeking. It accepts voice or typed input and the multi-LLM system decomposes the task, navigates to target pages, takes screenshots, and synthesizes a concise report with citation-linked screenshots. We make the process transparent through a progress dashboard combining sub-task progress and real-time exploration maps for seamless takeover. DroidRetriever also pauses on detected privacy or high-risk screens and prompts intervention. Across 35 tasks over 24 apps, experiments and user studies demonstrate improvements in coverage, transparency, and reduced workload. We release our code at https://github.com/AkimotoAyako/DroidRetriever.

2504.19102 2026-04-13 math.RT

Radial restriction of spherical functions on supergroups

Mitra Mansouri, Hadi Salmasian

Comments To appear in Journal of Lie Theory (special issue for Karl-Hermann Neeb's 60th birthday)

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Journal ref
Journal of Lie Theory 35 (2025), No. 4, 861--878
英文摘要

Using the Hopf superalgebra structure of the enveloping algebra $U(\mathfrak g)$ of a Lie superalgebra $\mathfrak=\mathrm{Lie}(G)$, we give a purely algebraic treatment of $K$-bi-invariant functions on a Lie supergroup $G$, where $K$ is a sub-supergroup of $G$. We realize $K$-bi-invariant functions as a subalgebra $\mathcal A(\mathfrak g,\mathfrak k)$ of the dual of $U(\mathfrak g)$ whose elements vanish on the coideal $\mathcal I=\mathfrak kU(\mathfrak g)+U(\mathfrak g)\mathfrak k$, where $\mathfrak k=\mathrm{Lie}(K)$. Next, for a general class of supersymmetric pairs $(\mathfrak g,\mathfrak k)$, we define the radial restriction of elements of $\mathcal A(\mathfrak g,\mathfrak k)$ and prove that it is an injection into $S(\mathfrak a)^*$, where $\mathfrak a$ is the Cartan subspace of $(\mathfrak g,\mathfrak k)$. Finally, we compute a basis for $\mathcal I$ in the case of the pair $(\mathfrak{gl}(1|2), \mathfrak{osp}(1|2))$, and uncover a connection with the Bernoulli and Euler zigzag numbers.

2504.17105 2026-04-13 math.DS math.AT

Conley-Morse persistence barcode: a homological signature of combinatorial bifurcations

Tamal K. Dey, Michał Lipiński, Manuel Soriano-Trigueros

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英文摘要

Bifurcation characterizes the qualitative changes in parameterized dynamical systems and is one of the major topics in the field. In this work, we study combinatorial bifurcations within the framework of combinatorial dynamical systems -- a young but already well-established theory. We introduce the Conley-Morse persistence barcode, a compact algebraic descriptor of combinatorial bifurcations. This barcode captures structural changes in a dynamical system at the level of Morse decompositions and provides a characterization of the nature of observed transitions in terms of the Conley index. The construction of Conley-Morse persistence barcode builds upon ideas from topological persistence. Specifically, we consider a persistence module obtained from the Conley index of invariant sets indexed over a poset. Using gentle algebras, we prove that this module decomposes into simple intervals (bars) and compute them by adapting the zigzag persistence algorithm to our purpose.

2504.06409 2026-04-13 physics.optics astro-ph.IM gr-qc physics.ins-det

High-Precision Lunar Corner-Cube Retroreflectors: A Wave-Optics Perspective

Slava G. Turyshev

Comments 26 pages, 6 figures, 12 tables

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Journal ref
Experimental Astronomy 61, 13 (2026)
英文摘要

High-precision corner-cube retroreflectors (CCRs) are critical for advanced lunar laser ranging (LLR) because they enable sub-millimeter-scale measurements of the Earth-Moon distance -- a level of precision essential for rigorous tests of relativistic gravitation and for advancing our understanding of lunar geophysics. In this work, we develop a comprehensive two-dimensional Fourier-optics model for single CCRs with apertures ranging from 80-110 mm. Our model incorporates realistic thermal-mechanical wavefront errors, detailed diffraction effects, and velocity aberration offsets. Our analysis reveals a strong coupling between aperture size and aberration angular offset: while larger CCRs deliver high on-axis flux under near-ideal conditions, their narrow diffraction lobes suffer significant flux loss at moderate aberration offsets, thereby favoring smaller apertures with broader main lobes. Furthermore, comparisons between solid fused-silica and hollow silicon-carbide (SiC) CCRs show that hollow designs not only achieve competitive or superior photon return -- particularly at 1064 nm, where phase errors are relatively reduced -- but also offer nearly an order-of-magnitude mass reduction for the same aperture sizes. These results establish a robust quantitative framework for optimizing CCR designs to perform at the sub-millimeter level under realistic lunar conditions and underscore the advantages of precision hollow SiC CCRs for next-generation LLR operations.

2504.05834 2026-04-13 physics.flu-dyn cond-mat.stat-mech physics.comp-ph

Geometry-Driven Segregation in Periodically Textured Microfluidic Channels

Fatemeh S. Ahmadi, Hossein Hamzehpour, Reza Shaebani

Comments 9 pages, 9 figures

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Journal ref
Phys Fluids 38, 043611, 2026
英文摘要

We investigate the transport dynamics of elongated microparticles in microchannel flows. While smooth-walled channels preserve the dependence of particle trajectories on initial orientation and lateral position, we show that introducing periodically textured walls can trigger robust alignment of the particle along the channel centerline. This geometry-driven alignment arises from repeated reorientations generated by spatially modulated shear gradients near the textured walls. The alignment efficiency depends on particle elongation and the relative texture wavelength, with an optimal range for maximal effect. While the observed alignment behavior is not limited to low Reynolds numbers, the characteristic alignment length scale diverges as the Reynolds number increases toward the turbulent flow regime. These findings offer a predictive framework for designing microfluidic devices that passively sort or focus anisotropic particles, with implications for soft matter transport, biophysical flows, and microfluidic engineering.

2503.15440 2026-04-13 math.CO math.RT

Counting $\mathbb F_q$-points of orbital varieties in ad-nilpotent ideals of type $A_n$

Mohammad Bardestani, Keivan Mallahi-Karai, Samrith Ram, Hadi Salmasian

Comments Major revisions in Sections 1 and 2. Theorem 1.6 in the current version is a new result

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Let $\mathfrak b_n(\mathbb F_q)$ denote the Lie algebra of upper triangular $n\times n$ matrices over the finite field $\mathbb F_q$, and let $\mathfrak u_n(\mathbb F_q)$ be the nilradical of $\mathfrak b_n$. For every $\mathfrak b_n(\mathbb F_q)$-stable ideal $\mathfrak a$ of $\mathfrak u_n(\mathbb F_q)$, and every partition $μ$ of $n$, we prove two formulas for the number of elements of $\mathfrak a$ of Jordan type $μ$: the first one is the Hall scalar product of a modified Hall-Littlewood function indexed by $μ$ and a chromatic quasisymmetric function associated to $\mathfrak a$, and the second one is in terms of an explicit collection of standard tableaux. In the special case that $\mathfrak a$ is the nilradical $\mathfrak u_Λ(\mathbb F_q)$ of the parabolic subalgebra associated to a composition $Λ$ of $n$, our first formula reduces to a result of Karp and Thomas: up to an explicit polynomial factor in $q$, the number of elements in $\mathfrak u_Λ(\mathbb F_q)$ of Jordan type $μ$ is equal to the coefficient of the monomial $\mathsf x^Λ$ in the specialization of the dual Macdonald symmetric function $\mathrm Q_{μ'}(\mathsf x;q^{-1},t)$ at $t=0$. We give three applications: (1) a formula for the number of points of a nilpotent Hessenberg variety, (2) a formula for the number of $X\in \mathfrak u_Λ(\mathbb F_q)$ that satisfy $X^2=0$, which in the special case $Λ=(1^n)$ is different from the Kirillov-Melnikov-Ekhad-Zeilberger formula, and (3) a formula for the number of double cosets $\mathrm U_1\backslash\mathrm{GL}_n(\mathbb F_q)/\mathrm U_2$ where $\mathrm U_1$ and $\mathrm U_2$ are unipotent subgroups corresponding to two $\mathfrak b_n(\mathbb F_q)$-stable ideals.

2503.13242 2026-04-13 math.LO

On groups definable in geometric fields with generic derivations

Anand Pillay, Françoise Point, Silvain Rideau-Kikuchi

Comments 10 pages

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英文摘要

We study groups definable in existentially closed geometric fields with commuting derivations. Our main result is that such a group can be definably embedded in a group interpretable in the underlying geometric field. Compared to earlier work of the first two authors toguether with K. Peterzil, the novelty is that we also deal with infinite dimensional groups.

2503.11752 2026-04-13 astro-ph.GA

BlackTHUNDER strikes twice: rest-frame Balmer-line absorption and high Eddington accretion rate in a Little Red Dot at $z=7.04$

Francesco D'Eugenio, Roberto Maiolino, Michele Perna, Hannah Uebler, Xihan Ji, William McClymont, Sophie Koudmani, Debora Sijacki, Ignas Juodžbalis, Jan Scholtz, Jake Bennett, Andrew J. Bunker, Stefano Carniani, Stéphane Charlot, Giovanni Cresci, Emma Curtis-Lake, Elena Dalla Bontà, Kohei Inayoshi, Gareth C. Jones, Jianwei Lyu, Alessandro Marconi, Giovanni Mazzolari, Erica J. Nelson, Eleonora Parlanti, Brant E. Robertson, Raffaella Schneider, Charlotte Simmonds, Sandro Tacchella, Giacomo Venturi, Chris Willott, Joris Witstok, Callum Witten

Comments 13 pages, 7 figures. Published in MNRAS

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英文摘要

JWST has revealed a population of 'Little Red Dots' (LRDs): compact, red objects at redshifts z=2-9 with 'v'-shaped spectral energy distributions, broad permitted lines, and, often, hydrogen Balmer absorption. We use NIRSpec/IFS data from the BlackTHUNDER survey to study the H$α$ line in the LRD Abell2744-QSO1 at z=7.04, which is a confirmed AGN due to time-variable equivalent width (EW) in its broad emission lines. The H$α$ spectral profile is non-Gaussian, requiring at least two Gaussian components. We also detect a narrow-line Gaussian component, and strong H$α$ absorption (EW relative to the continuum $\sim 22_{-7}^{+12} \mathring{\mathrm{A}}$), confirming a connection between the strong Balmer break and line absorption. The absorber is at rest with respect to broad H$α$, suggesting that the gas cannot be interpreted as an inflow or outflow, forming instead a long-lived structure. Its velocity dispersion is $σ_{\rm abs}=110_{-10}^{+20}$ km s$^{-1}$, consistent with the value inferred from the analysis of the Balmer break. Based on H$α$, we infer a black hole mass of log($M_{\rm BH}/{\rm M_\odot}$)=7.2, smaller but close to the previous estimates based on H$β$. The Eddington ratio is 0.09. Combining the high signal-to-noise ratio of the narrow H$α$ line with the spectral resolution R=3,700 of the G395H grating, we infer a narrow-line intrinsic dispersion $σ_{\rm n}=22_{-6}^{+5}$ km s$^{-1}$, which places a stringent constraint on the black-hole-to-dynamical-mass ratio of this system to be $M_{\rm BH}/M_{\rm dyn}$=0.15-1.2, confirming the overmassive nature of the black hole and potentially leaving little room for a host galaxy.

2501.16949 2026-04-13 math.FA

Frames for source recovery from non-uniform dynamical samples

Ruchi, Lalit Kumar Vashisht

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Journal ref
International Journal of Wavelets, Multiresolution and Information Process 2026
英文摘要

Motivated by the work of Aldroubi et al., we investigate the stability of the source term of the discrete dynamical system indexing over a non-uniform discrete set arising from spectral pairs in infinite-dimensional separable Hilbert spaces. Extending results due to Aldroubi et al., firstly, we give a necessary and sufficient condition for the recovery of the source term in finitely many iterations. Afterwards, we derive a necessary condition for the stability of the source term in finitely many iterations when it belongs to the closed subspace of an infinite-dimensional separable Hilbert space. Finally, we give a necessary and sufficient condition for the recovery of the source term in infinitely many iterations.

2501.16773 2026-04-13 math.AC math.AG

BCM-thresholds of non-principal ideals

Sandra Rodríguez-Villalobos, Karl Schwede

Comments 27 pages, section 6 on multiplicity added, numerous minor corrections and typos fixed. Comments welcome

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英文摘要

Generalizing previous work of the first author, we introduce and study a characteristic free analog of the $F$-threshold for non-principal ideals, BCM-thresholds. We show that this coincides with the classical $F$-threshold for weakly $F$-regular rings and that the set of BCM-thresholds coincides with the set of BCM-jumping numbers in a complete local regular ring. We obtain results on $F$-thresholds of parameter ideals analogous to results of Huneke-\mustata-Takagi-Watanabe as well as a mixed characteristic version of one of their results on multiplicity. Instead of taking ordinary powers of an ideal, our definition uses fractional integral closure in an absolute integral closure of our ambient ring.

2501.15506 2026-04-13 cond-mat.stat-mech cond-mat.str-el math-ph math.MP quant-ph

Complete classification of integrability and non-integrability of S=1/2 spin chains with symmetric next-nearest-neighbor interaction

Naoto Shiraishi

Comments 72 pages, no figure

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Journal ref
J. Stat. Phys. 192, 170 (2025)
英文摘要

We study S=1/2 quantum spin chains with shift-invariant and inversion-symmetric next-nearest-neighbor interaction, also known as zigzag spin chains. We completely classify the integrability and non-integrability of the above class of spin systems. We prove that in this class there are only two integrable models, a classical model and a model solvable by the Bethe ansatz, and all the remaining systems are non-integrable. Our classification theorem confirms that within this class of spin chains, there is no missing integrable model. This theorem also implies the absence of intermediate models with a finite number of local conserved quantities.

2501.01663 2026-04-13 math.CV

Geometric analysis of a class of harmonic mappings defined by a differential inequality

Vasudevarao Allu, Raju Biswas, Rajib Mandal

Comments 10 Pages, 2 figures and 1 table

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英文摘要

In this paper, we introduces and undertake as a systematical investigation of the class $\mathcal{P}_{\mathcal{H}}^{0}(α,M)$ of normalized harmonic mappings $f = h + \overline{g}$ in the unit disk $\mathbb{D}$, defined by the differential inequality \[ \text{Re}\left((1-α)h'(z) + αz h''(z)\right) > -M + \left|(1-α)g'(z) + αz g''(z)\right|\quad\text{for}\quad z\in\Bbb{D}, \] where $M > 0$, $α\in (0,1]$, and $g'(0) = 0$. This class extends the harmonic analogue of functions with positive real part and offers a unified framework for analyzing their geometric characteristics. We obtain sharp coefficient bounds for both the analytic and co-analytic parts, establish sharp growth bounds, and determine the radii of univalency, starlikeness, and convexity. Furthermore, we show that $\mathcal{P}_{\mathcal{H}}^{0}(α,M)$ is closed under convex combinations, and under suitable restrictions on the parameters, it is also closed under convolution. Our findings generalize and extend several known results in the theory of harmonic mappings.

2412.15031 2026-04-13 quant-ph gr-qc physics.optics

Ultimate tradeoff relation of quantum precision limits in multiparameter linear measurement

Guolong Li, Xiao-Ming Lu

Comments 18 pages, 6 figures

详情
英文摘要

Linear measurements are widely applied in sensing classical signals, e.g., gravitational wave (GW), and are developing toward joint measurement of multiple parameters. In this Letter, we aim at multiparameter linear measurements to classical monochromatic signals, and establish an ultimate tradeoff relation that tightly constrains the quantum limits on estimation precision. The tradeoff relation is fundamental since it is rooted in Heisenberg's uncertainty principle, and completely characterizes the dependence between the attainable precision limits on the estimated parameters. Eventually, we identify a necessary condition under which an optimal measurement protocol saturates the tradeoff relation, and show that the measurement phase can be regulated to implement flexible allocation of precision weights. Our finding can offer valuable guidance for detuned GW sensors in ultra-sensitive searches for post-merger remnants.

2411.15627 2026-04-13 math.ST stat.TH

Community detection for binary graphical models in high dimension

Julien Chevallier, Guilherme Ost

详情
英文摘要

Let $N$ components be partitioned into two communities, denoted ${\cal P}_+$ and ${\cal P}_-$, possibly of different sizes. Assume that they are connected via a directed and weighted Erdös-Rényi (DWER) random graph with unknown parameter $ p \in (0, 1).$ The weights assigned to the existing connections are of mean-field-type, scaling as $N^{-1}$. At each time \modif{step}, we observe the state of each component: either it sends some signal to its successors (in the directed graph) or remains silent otherwise. In this paper, we show that it is possible to find the communities ${\cal P}_+$ and ${\cal P}_-$ based only on the activity of the $N$ components observed over $T$ time units. More specifically, we propose \modif{ two simple methods, an aggregated method and a spectral method, whose {\it misclassification rates} vanish as long as $T \gg N$ (up to log terms). This condition is proved to be near-optimal in the minimax sense. Moreover, under the stronger condition $T \gg N^2$ (up to log terms), the aggregated method is shown to achieve {\it exact recovery} with probability tending to $1$. } Interestingly, these simple \modif{methods} do not require any prior knowledge of the other model parameters (e.g. the edge probability $p$). The key step in our analysis is to derive an asymptotic approximation of the 1-lagged covariance matrix associated to the states of the $N$ components, as $N$ diverges. This asymptotic approximation relies on the study of the behavior of the solutions of a \modif{Stein-type} matrix equation satisfied by the simultaneous (0-lagged) covariance matrix associated to the states of the components. This study is challenging, especially because the simultaneous covariance matrix is random since it depends on the underlying DWER random graph.

2410.11467 2026-04-13 math.AP cs.NA math.NA

On $L^\infty$ stability for wave propagation and for linear inverse problems

Rima Alaifari, Giovanni S. Alberti, Tandri Gauksson

Comments 29 pages, 8 figures

详情
Journal ref
Journal of Hyperbolic Differential Equations, Vol. 23, No. 01, pp. 3-33 (2026)
英文摘要

Stability is a key property of both forward models and inverse problems, and depends on the norms considered in the relevant function spaces. For instance, stability estimates for hyperbolic partial differential equations are often based on energy conservation principles, and are therefore expressed in terms of $L^2$ norms. The focus of this paper is on stability with respect to the $L^\infty$ norm, which is more relevant to detect localized phenomena. The linear wave equation is not stable in $L^\infty$, and we design an alternative solution method based on the regularization of Fourier multipliers, which is stable in $L^\infty$. Furthermore, we show how these ideas can be extended to inverse problems, and design a regularization method for the inversion of compact operators that is stable in $L^\infty$. We also discuss the connection with the stability of deep neural networks modeled by hyperbolic PDEs.

2410.01921 2026-04-13 math.GT

Bridge Multisections of Knotted Surfaces in $S^4$

Román Aranda, Carolyn Engelhardt

Comments 23 pages, 25 figures, comments welcome V2: Final accepted version - included more examples in Section 4

详情
英文摘要

Bridge multisections are combinatorial descriptions of surface links in 4-space using tuples of trivial tangles. They were introduced by Islambouli, Karimi, Lambert-Cole, and Meier to study curves in rational surfaces. In this paper, we prove a uniqueness result for bridge multisections of surfaces in 4-space: we give a complete set of moves relating to any two multiplane diagrams of the same surface. This is done by developing a surgery operation on multiplane diagrams called band surgery. Another application of this surgery move is that any $n$-valent graph with an $n$-edge coloring is the spine of a bridge multisection for an unknotted surface. We also prove that any multisected surface in $S^4$ can be unknotted by finitely many band surgeries.

2409.04765 2026-04-13 math.OC cs.SY eess.SY

Continuous-Time Distributed Seeking for Variational Generalized Nash Equilibrium of Online Game

Jianing Chen, Sichen Qian, Chuangyin Dang, Sitian Qin

Comments Accepted by IEEE Transactions on Automatic Control

详情
英文摘要

This paper mainly investigates a class of distributed Variational Generalized Nash Equilibrium (VGNE) seeking problems for both online noncooperative games and online aggregative games with time-varying coupling inequality constraints. Two novel continuous-time distributed VGNE seeking algorithms are proposed, which realize the constant regret bound and sublinear fit bound, superior to those of the criteria for online optimization problems and online games. Furthermore, to reduce unnecessary communication among players, a dynamic event-triggered mechanism involving internal variables is introduced into the distributed VGNE seeking algorithm, while the constant regret bound and sublinear fit bound are still maintained. Also, the Zeno behavior is strictly prohibited. Moreover, we further investigate the impact of communication noise on the player's measurement of its neighbors' relative states. It is demonstrated that both the regret and fit bounds remain valid as long as the noise level is not excessively large. This result reveals, to some extent, the proposed algorithm's noise-resilient capability. Finally, an online Uncrewed Aerial Vehicle (UAV) swarm game and an online Nash-Cournot game are given to demonstrate the validity of the theoretical results.

2408.06691 2026-04-13 nlin.CG cond-mat.stat-mech

Complete ergodicity in one-dimensional reversible cellular automata

Naoto Shiraishi, Shinji Takesue

Comments 63 pages, 47 figures

详情
Journal ref
J. Stat. Phys. 192, 165 (2025)
英文摘要

Exactly ergodicity in boundary-driven semi-infinite cellular automata (CA) are investigated. We establish all the ergodic rules in CA with 3, 4, and 5 states. We analytically prove the ergodicity for 12 rules in 3-state CA and 118320 rules in 5-state CA with any ergodic and periodic boundary condition, and numerically confirm all the other rules non-ergodic with some boundary condition. We classify ergodic rules into several patterns, which exhibit a variety of ergodic structure.