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2605.07261 2026-05-11 cs.IT math.IT

Movable Subarray-Aided Hybrid Beamforming for Near-Field Multiuser Communications

Xiangqian Xu, Songjie Yang, Arumugam Nallanathan

AI总结 本文研究了可移动子阵列辅助的混合波束成形技术,用于近场多用户通信系统,旨在解决现有设计中对大规模MIMO波束成形硬件限制与近场空间自由度利用不足之间的矛盾。通过结合可移动子阵列的位置调整与混合波束成形,该方法能够同时利用近场距离相关和子阵列位置相关的自由度,实现高精度波束聚焦和优异的干扰抑制。此外,文中提出了一种混合平面-球面波模型以降低计算复杂度,并设计了基于分数规划和ADMM的交替优化算法,仿真结果验证了其在总速率上的显著提升。

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英文摘要

Movable antenna (MA)-enabled near-field (NF) communications offer significant potential for 6G, yet existing designs often neglect the practical constraints of hybrid beamforming (HBF) for extremely large-scale MIMO (XL-MIMO). Conversely, MA-aided HBF frequently overlooks the rich NF degrees of freedom (DoFs). This paper proposes a movable subarray (MSA)-aided HBF architecture for NF multiuser systems, which strikes a strategic balance between hardware practicality and spatial flexibility. By coupling MSA movement with HBF, the proposed design simultaneously exploits NF distance-dependent and MSA position-dependent DoFs, enabling highly precise beamfocusing and superior interference mitigation. To alleviate the computational burden, a hybrid planar-spherical wave model is introduced for efficient channel approximation. Furthermore, an alternating optimization (AO) algorithm is developed by integrating fractional programming, the alternating direction method of multipliers (ADMM), and projected gradient ascent. Simulation results validate substantial sum-rate gains over fixedposition antenna (FPA) benchmarks.

2605.07259 2026-05-11 cs.LO

Evidence-Tracked Tape Semantics for Probabilistic Computation

Liron Cohen, Tomer Samara

AI总结 本文提出了一种基于证据追踪的磁带语义,用于对概率计算进行形式化描述。该方法通过单调核到证据框架的转换流程,构建了一个高阶逻辑系统,其中蕴含关系由统一的证据变换器见证,并能够通过磁带度量提取数值摘要来恢复定量陈述。研究还探讨了在扩展层面上丢失的内部原理,并通过推前映射将磁带推理与扩展层定律语义联系起来,提出了一个用于概率一推理的可靠抽象。

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Journal ref
11th International Conference on Formal Structures for Computation and Deduction, Jul 2026, Lisbon, Portugal
英文摘要

A standard intensional account of probabilistic computation represents a randomized program as a deterministic computation that consumes an explicit random tape. This yields a two-layer perspective: an intensional layer that makes reuse of randomness and correlation visible, and an extensional layer obtained by interpreting tapes under a chosen probability measure. We develop an evidence-tracked tape semantics using the monadic-core-to-evidenced-frame pipeline (and its induced realizability tripos), obtaining a higher-order logic in which entailments are witnessed by uniform evidence transformers. Quantitative statements are recovered by interpretation: once a tape measure is fixed, probabilities and expectations arise by extracting numerical summaries from tape-indexed predicates, and entailments yield sound inequalities, with an almost-sure quotient supporting probability-one reasoning. We also study intensional principles that are lost at the level of laws, including proof-relevant transport along realizable tape-rewiring maps and a canonical splitting discipline for stream tapes enforcing independent draws. Finally, we relate tape-based reasoning to an extensional law semantics via pushforward, isolating a probability-one must abstraction as a sound summary of tape-based proofs.

2605.07258 2026-05-11 nucl-th

$Ξ$-deuteron low-energy $s$-wave phase shifts and momentum correlation functions in Faddeev formulation

M. Kohno, H. Kamada

AI总结 本文通过求解Faddeev方程,研究了低能Ξ-氘核散射问题,采用三种当前可用的Ξ-核子相互作用参数化形式进行计算。研究给出了J=3/2和J=1/2态下的s波相移,并基于动量空间的Faddeev振幅构建了坐标空间的三体波函数,用于计算Ξd动量关联函数。结果表明,氘核解离效应在J=3/2通道中尤为显著,不同相互作用参数化导致的关联函数幅值差异反映了ΞN相互作用在自旋-同位旋通道中的定量差别,未来实验数据有望进一步完善对ΞN相互作用的理解。

Comments 9 pages, 10 figures

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英文摘要

The low-energy $Ξ$-deuteron scattering is investigated through the solution of Faddeev equations, employing three sets of the currently available parametrization of the $Ξ$-nucleon interactions. One of these is the chiral NLO interaction parametrized by the Jülich group, and the other two are based on the calculations by the HAL-QCD method. The $s$-wave phase shifts in the $J=3/2$ and $J=1/2$ states are presented. Three-body wave functions in coordinate space are constructed from the Faddeev amplitudes in momentum space. These functions are used in the calculation of $Ξd$ momentum correlation functions. The effects of the deuteron breakup are significant in the $J=3/2$ channel. The differences in the magnitude of the calculated correlation function show the quantitative difference of the $ΞN$ interactions in the spin-isospin channels. The prospective experimental data on the $Ξd$ momentum correlation function could contribute to a better description of the $ΞN$ interactions.

2605.07255 2026-05-11 astro-ph.HE

Resonant Inverse Compton Scattering and Hard X-ray Emission in Magnetar Magnetospheres

Kun Hu, Nicholas Rackers, Alexander Y. Chen

AI总结 该研究探讨了磁星磁层中共振逆康普顿散射对硬X射线辐射的贡献。通过计算磁层中电子-正电子对流的共振散射不透明度及辐射光谱和偏振特性,发现共振冷却显著影响磁层等离子体密度,并对硬X射线区域的光学深度提出严格限制。研究还指出,在IXPE观测几何下,恒星表面附近的赤道扭结构可以很好地解释4U 0142+61的NuSTAR硬X射线谱,而极区扭结构则不太可能。

Comments 20 pages, 13 figures, submitted to ApJ

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英文摘要

Magnetars are a subclass of neutron stars with ultra-strong surface magnetic fields. Some magnetars exhibit persistent hard X-ray emission, characterized by power-law tails with photon indices around 1--1.5, extending from ${\sim}$10 keV to several hundred keV. The leading explanation for this hard X-ray component is resonant Compton scattering, in which the thermal seed photons are upscattered by relativistic electron-positron pairs flowing along magnetic field lines in the magnetosphere. In this work, we adopt the pair outflow framework of the magnetar magnetosphere and calculate the resonant Compton scattering opacity, as well as the spectrum and polarization of the upscattered emission. We find that resonant cooling can substantially modify the magnetospheric plasma density and impose strong optical depth constraints on the hard X-ray emission regions. Under the viewing geometry inferred from IXPE, an equatorial twist near the stellar surface provides a viable configuration for the NuSTAR hard X-ray spectrum of 4U 0142+61, while a polar-twist geometry is disfavored. Joint spectral, timing, and polarimetric modeling will be essential for distinguishing between the magnetospheric scattering geometries and understanding the physical properties of the pair plasma.

2605.07249 2026-05-11 cs.IR

MLAIRE: Multilingual Language-Aware Information Retrieval Evaluation Protocal

Youngjoon Jang, Seongtae Hong, Hyeonseok Moon, Heuiseok Lim

AI总结 随着多语言信息检索在现实场景中的重要性日益提升,现有评估方法大多仅关注语义相关性,而忽略了语言因素对检索效果的影响。为此,本文提出MLAIRE,一种多语言语言感知的信息检索评估协议,通过构建多语言平行语料库,分离语义检索与查询语言偏好,引入语言偏好率(LPR)和Lang-nDCG等指标,揭示了不同检索模型在语义相关性和语言匹配性上的差异,为多语言检索系统的优化提供了新的评估视角。

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英文摘要

Multilingual Information Retrieval is increasingly important in real-world search settings, where users issue queries over mixed-language corpora. Existing evaluations mainly reward language-agnostic semantic relevance, treating relevant passages equally regardless of language. Yet retrieval utility also depends on the language of the retrieved passages: users may prefer results they can read and verify in the query language, and query--passage language mismatch can complicate downstream grounding and answer verification in Retrieval-Augmented Generation systems. To evaluate this language-aware dimension, we introduce MLAIRE, a Multilingual Language-Aware Information Retrieval Evaluation protocol that disentangles cross-lingual semantic retrieval from query-language preference. MLAIRE constructs controlled pools with parallel passages across languages, enabling measurement of semantic retrieval accuracy and query-language preference when equivalent translations are available. We propose language-aware metrics, including Language Preference Rate (LPR) and Lang-nDCG, together with a 4-way decomposition separating semantic and query-language preference failures. Evaluating 31 dense, sparse, and late-interaction retrievers, we show that standard metrics obscure distinct behaviors: semantically strong retrievers may return correct content in a non-query language, while retrievers with stronger query-language preference may retrieve less semantically relevant passages.

2605.07246 2026-05-11 math.NA cs.NA

Variable decoupling and the Kolmogorov Superposition Theorem for rational functions

A. C. Antoulas, I. V. Gosea, C. Poussot-Vassal

AI总结 本文研究了有理函数的变量解耦问题,指出对于多变量有理函数,可以通过直接构造的方式实现柯尔莫哥洛夫叠加定理(KST)中的单变量函数,无需额外计算。核心方法基于Loewner框架,能够高效地处理多变量函数的结构分解。该成果为用低复杂度的有理函数和多项式逼近多变量非有理函数提供了理论依据和实用工具。

Comments 14 pages, 1 figure

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英文摘要

This work shows that for rational multivariate functions, the Kolmogorov Superposition Theorem (KST) involves several single-variable functions, which can be written down by inspection. In other words, no computation is required for decoupling the variables of multivariate rational functions. The key tool for this development is the Loewner Framework for multivariate functions. Applications of this result involve approximating multivariate non-rational functions by low-complexity multivariate rational and polynomial functions.

2605.07245 2026-05-11 cs.AR

TransDot: An Area-efficient Reconfigurable Floating-Point Unit for Trans-Precision Dot-Product Accumulation for FPGA AI Engines

Jiayi Wang, Maohua Nie, Sin-Chen Lin, C. -J. Richard Shi, Ang Li

AI总结 本文提出了一种名为TransDot的可重构浮点单元,旨在提高FPGA人工智能引擎中点积累加操作的效率。该设计统一了多精度SIMD FMA和跨精度点积累加操作,通过共享的可重构数据路径实现,支持FP16、FP8和FP4等多种精度的点积累加到FP32。实验表明,TransDot在面积效率方面优于现有方案,并能显著提升不同精度下的吞吐量,为下一代FPGA AI加速器提供了更高效的硬件支持。

Comments To appear in FCCM 2026

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英文摘要

Commercial FPGAs, such as AMD Versal devices, increasingly incorporate AI engines that exploit low-precision packed-SIMD fused multiply-accumulate (FMA) to achieve proportional throughput gains. However, trans-precision FMA (e.g., multiplying two FP16 numbers and adding their result to an FP32 accumulator), which preserves numerical stability by accumulating in higher precision, remains bottlenecked by the highest-precision, lowest-throughput operation. Dot-product accumulation (DPA) (e.g., performing a dot-product on two 4-element FP8 vectors and adding its result to an FP32 accumulator) can fully utilize the input/output bandwidth and computational resources. Existing flexible open-source FPUs, such as FPnew, do not support DPA and implement SIMD FMA on low-precision formats by replicating independent FMA lanes, which increases area, underutilizes shared arithmetic resources, and complicates the integration of DPA operations. This paper presents TransDot, a reconfigurable FPU that unifies multi-precision SIMD FMA and trans-precision DPA within a shared, reconfigurable datapath. TransDot extends the baseline design with 2-term FP16, 4-term FP8, and 8-term FP4 dot-product accumulation into FP32 using reconfigurable subcomponents. Evaluation shows that TransDot delivers 2$\times$ FP16, 4$\times$ FP8, and 8$\times$ FP4 throughput via DPA with FP32 accumulation, and 1.46$\times$ area efficiency in FP16 DPA and 2.92$\times$ area efficiency in FP8 DPA, at the cost of 37.3% larger area on average and an additional pipeline stage in dot-product mode compared to the FPnew baseline. These results demonstrate that TransDot's area-efficient design enables scalable deployment in next-generation AMD Versal AI engines.

2605.07241 2026-05-11 cs.CR eess.AS

Asymmetric Phase Coding Audio Watermarking

Guang Yang, Amir Ghasemian, Ninareh Mehrabi, Homa Hosseinmardi

AI总结 随着深度伪造音频技术的兴起,基于语音的身份认证系统面临严峻挑战。本文提出了一种名为 Asymmetric Phase Coding(APC)的训练无关音频水印方法,结合数字签名、错误校正和频域特征编码,实现了紧凑、不可否认且可盲提取的水印,能够在多种攻击条件下保持高验证率。该方法在多个音频处理攻击场景中表现出优异的鲁棒性,并与现有神经网络水印方法进行了详细对比,具有较高的实用价值和可复现性。

Comments 13 pages, 12 figures, 3 tables

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英文摘要

The proliferation of deepfake audio challenges voice-based authentication systems; passive forensic detectors are sensitive to evolving generative models and to real-world channel distortions. We propose Asymmetric Phase Coding (APC), a training-free cryptographic signing layer for audio, designed as a compact and auditable provenance primitive that can stand alone or be stacked with learned watermarks. APC combines Ed25519 digital signatures (EdDSA, FIPS 186-5; 64-byte signatures) with Reed-Solomon error correction, pseudo-random STFT phase-bin selection, and a redundant quantization-index-modulation (QIM) code on log-magnitude differences of adjacent bin pairs, yielding a compact, non-repudiable, blind-extractable watermark. We evaluate APC on 1,000 LibriSpeech test-clean clips (10 s each, 44.1 kHz) under eight attack configurations -- identity, 10% end-cropping, 20% end-cropping, 8 kHz low-pass, 16 kHz round-trip resampling, FLAC re-encoding, MP3 at 128 kbps, and OGG-Vorbis at 128 kbps -- and achieve cryptographic verification rates between 97.5% and 98.3% on every condition at mean PESQ=3.02 and tens-of-milliseconds CPU latency. We explicitly compare APC against recent neural baselines (AudioSeal, WavMark, SilentCipher), detail the threat model (forgery resistance vs. erasure), characterize the dataset, define all metrics, quantify an adaptive white-box erasure attack, and release code, keys, and metadata for reproducibility.

2605.07240 2026-05-11 cs.MA

Rethinking Priority Scheduling for Sequential Multi-Agent Decision Making in Stackelberg Games

Xiangyu Liu, Liang Zhang, Bo Jin, Ziqi Wei

AI总结 本文研究了在N级斯塔克尔伯格博弈中,智能体决策顺序对博弈均衡的影响,指出默认的决策顺序可能导致非均衡解,并提出了一种分层优先级调整(HPA)方法,通过上层策略动态选择最优决策顺序,下层智能体按照选定顺序在时空序马尔可夫博弈中执行策略,实验表明该方法在多智能体控制任务中优于现有算法,具有良好的环境适应性。

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英文摘要

Current research applying N-level Stackelberg Game to multi-agent systems often uses the default decision order of agents provided by the environment. However, this raises the question: does the order of agents necessarily affect the final equilibrium point of the game? To address this, we formally analyze the N-level Stackelberg Game, where changing the order in which agents make decisions typically leads to an overdetermined system. As a result, the equilibrium point shifts unless special structural conditions are satisfied. Based on this analysis, we propose the Hierarchical Priority Adjustment (HPA) method, which adjusts and selects the agents' decision order. At the upper level, an upper policy dynamically selects the optimal decision order of agents based on the current game state. At the lower level, agents execute strategies in the Spatio-Temporal Sequential Markov Game (STMG) according to the selected order. To coordinate learning across time scales, we employ a slow-fast update scheme with shared intrinsic rewards derived from the advantage function of the upper policy. Experimental results on high-precision control tasks, including multi-agent MuJoCo, show that HPA outperforms benchmark algorithms and robustly adapts to changing environments. These results highlight the crucial role of optimizing the agents' decision order in N-level Stackelberg Game.

2605.07238 2026-05-11 cs.DC

FATE: Future-State-Aware Scheduling for Heterogeneous LLM Workflows

Zirui Huang, Yi-Xiang Hu, Feng Wu, Xiangyang Li

AI总结 随着大语言模型(LLM)应用越来越多地以异构多阶段工作流的形式运行,调度策略不仅要考虑当前可执行的阶段,还需关注对后续阶段执行状态的影响。本文提出FATE,一种面向未来状态的异构LLM工作流调度器,通过结合前沿规划、多维状态感知的代价估计和分片执行等技术,综合优化当前与未来执行状态,有效降低端到端延迟。实验表明,FATE在多个基准测试中显著优于现有方法,验证了其在多维未来状态保留方面的优越性。

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英文摘要

Large language model (LLM) applications are increasingly executed as heterogeneous multi-stage workflows rather than isolated inference calls. In these workflow directed acyclic graphs (DAGs), scheduling decisions affect not only the currently ready stage, but also the execution state inherited by downstream stages, including model residency, parent-output locality, prefix reuse, and future device reachability. Existing serving and DAG-scheduling policies mainly optimize immediate queue state, placement cost, or reuse signals in isolation, which can fragment useful state and increase end-to-end latency. We present FATE, a future-state-aware scheduler for heterogeneous LLM workflows. FATE combines a CP-SAT-backed frontier planner, horizon-aware candidate scoring, bounded multi-device shard execution, and state-conditional cost estimation. Rather than solving a monolithic full-DAG problem, FATE repeatedly plans over the current ready frontier and scores assignments by both immediate cost and the downstream state they induce. Across real-DAG and controlled prefix-reuse benchmarks, FATE outperforms practical heuristics, classical DAG scheduling, and proxy adaptations of recent workflow-serving policies. On the real-DAG benchmark, it achieves normalized makespan and normalized P95 latency of 0.675 and 0.677, reducing them by 32.5% and 32.3% over RoundRobin and by 8.9% and 8.8% over the strongest non-FATE baseline. Mechanism analysis and ablations show that these gains arise from jointly preserving multiple dimensions of future execution state rather than prefix reuse alone. These results indicate that future-state preservation should be treated as a first-class scheduling objective for heterogeneous LLM workflow serving.

2605.07236 2026-05-11 gr-qc hep-th

Black holes at a finite distance: Quasi-local restricted phase space formalism

Bai-Hao Huang, Liu Zhao

AI总结 本文将限制相空间形式推广到准局域范围,研究位于有限径向距离的静态观测者所看到的球对称黑洞解的热力学性质。通过引入额外的热力学变量——压力和观测者所在超曲面的面积,证明了Reissner-Nordström(RN)和RN-AdS黑洞的第一定律和欧拉关系仍然成立。研究发现,在准局域描述下,RN黑洞的行为与渐近描述下显著不同,却与RN-AdS黑洞在渐近描述下的行为高度相似,例如表现出等电荷温度-熵相变而无等电压温度-熵相变;在中性极限下,准局域描述中还出现了渐近描述中缺失的类似霍金-页相变的现象。

Comments 19 pages,, 4 fifures

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英文摘要

We extend the restricted phase space formalism for spherically symmetric black hole solutions of Einstein-Maxwell theory to the quasi-local regime, with the static observers located at a finite radial distance. The first law and Euler relation for the RN and RN-AdS black holes are proved to hold, but only with the inclusion of an extra pair of thermodynamic variables, i.e. the pressure and the area of the codimension-2 hypersurface on which the observers reside. For the RN black holes, the quasi-local behavior is analyzed in detail. It turns out that the RN black holes in the quasi-local description behaves significantly different from itself in the asymptotic description, but is extremely similar to the RN-AdS black holes in the asymptotic description, e.g. allowing for isocharge temperature-entropy phase transitions and lack of isovoltage temperature-entropy phase transitions. In the neutral limit, the Hawking-Page-like transitions appear in the quasi-local description which is absent in the asymptotic description.

2605.07235 2026-05-11 astro-ph.HE astro-ph.CO

Anisotropic Thermal Conduction as a Driver of Jet Collimation and Magnetic Field Amplification on Cold Fronts

Nana Matsuno, Takaaki Yokoyama, Mami Machida

AI总结 该研究探讨了在星系团中,各向异性热传导如何影响活动星系核喷流的准直以及冷前沿区域磁场的增强。通过二维磁流体动力学模拟,研究发现热传导能够沿磁场线将热量从喷流头部输运至内侧泡状结构,从而提升其压力,使喷流准直程度提高约4倍,并使冷前沿表面的磁场强度增加约1.5倍。研究揭示了热传导在喷流尺度上可能起到准直作用,为理解星系团中喷流形态和磁场结构提供了新的理论依据。

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英文摘要

Galaxy clusters contain a hot, diffuse, and weakly magnetized plasma known as the intracluster medium (ICM). In this environment, how thermal conduction influences plasma dynamics and the conditions under which it operates efficiently remain open questions in cluster physics. Systems in which active galactic nuclei (AGN) jets interact with cold fronts produced by cluster mergers provide a unique setting to examine the interplay between conduction, jet dynamics, and ordered magnetic fields. To interpret the detailed structures revealed by recent observations, it is therefore important, as a first theoretical step, to quantify how thermal conduction modifies AGN jet morphology and the surrounding magnetic-field configuration. We perform two-dimensional magnetohydrodynamic (MHD) simulations of an AGN jet in an ICM environment, incorporating anisotropic thermal conduction with varying efficiency. The simulations show that thermal conduction transports heat from the jet head backward along magnetic field lines into the inner cocoon. This process increases the inner cocoon pressure, enhancing jet collimation by a factor of $\sim 4$ compared to models without conduction. This stronger collimation stretches the magnetic fields along the cold-front surface, resulting in a maximum field strength up to a factor of $\sim 1.5$ larger. Jet collimation increases as the conduction efficiency increases, which is interpreted as a conductive collimation mechanism. These results suggest that anisotropic thermal conduction can operate effectively on jet scales in galaxy clusters, and that accounting for conduction may be important when interpreting jet morphology and magnetic field structure in merging cluster environments.

2605.07231 2026-05-11 cond-mat.mes-hall cond-mat.stat-mech quant-ph

Topological Characterization of Discrete-Time Classical Stochastic Processes: Dual Role of Point-Gap Topology

Masaya Nakagawa, Masahito Ueda

AI总结 本文研究了离散时间格点马尔可夫链所描述的经典随机过程的拓扑特性,揭示了随机矩阵的点隙拓扑在不同参考点选择下具有两种不同的物理意义。围绕一般参考点的点隙拓扑与输运方向有关,而围绕复谱原点的非平凡拓扑则反映了反馈控制引起的非马尔可夫性。研究还揭示了麦克斯韦妖实验中定向输运的拓扑起源,并指出反馈控制的拓扑本质,进一步展示了拓扑强制的非马尔可夫经典过程可通过马尔可夫量子主方程模拟,表明了拓扑形式的量子优势。

Comments 14 pages, 5 figures

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英文摘要

We present topological characterization of classical stochastic processes described by discrete-time Markov chains on lattices. We point out that point-gap topology of stochastic matrices entails two distinct physical consequences that hinge on the choice of the reference point. The point-gap topology around a generic reference point is related to the direction of transport, and nontrivial topology around the origin of the complex spectrum of a stochastic matrix implies non-Markovianity caused by, e.g., feedback control. On the basis of this characterization, we identify the topological origin of directed transport in a classic experiment of Maxwell's demon [S. Toyabe et al., Nat. Phys. 6, 988 (2010)] and find the topological nature of feedback control beyond thermodynamic interpretation. We demonstrate that a topologically enforced non-Markovian classical stochastic process can be simulated by a Markovian quantum master equation, indicating a topological form of quantum advantage.

2605.07229 2026-05-11 quant-ph

Hardware-Free Polarization Stabilization for Measurement-Device-Independent Quantum Key Distribution via Correlated Twirling

Papon Pewkhom, Nattee Jeennugool, Norshamsuri Ali, Rosdisham Endut, Syed Alwee Aljunid, Pruet Kalasuwan

AI总结 测量设备无关量子密钥分发(MDI-QKD)虽具有检测器漏洞的无条件安全性,但其实际应用受到非对称信道湍流的严重限制。本文提出了一种无需硬件的偏振稳定技术,通过基于单位2设计的关联旋转协议,将确定性的非对称几何旋转数学转化为各向同性的Pauli退相干信道,从而在经典筛选阶段虚拟地抑制了2/3的固有信道噪声。该方法显著提升了Y偏置容忍度和绝对角偏差容忍度,为构建鲁棒的长距离量子网络提供了高效且可扩展的解决方案。

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英文摘要

Measurement-Device-Independent Quantum Key Distribution (MDI-QKD) provides unconditional security against detector vulnerabilities, but its practical deployment is severely hindered by asymmetric channel turbulence. Fluctuations in optical fibers induce arbitrary polarization drift, degrading Hong-Ou-Mandel interference and forcing extensive calibration downtime. In this work, we propose a hardware-free polarization stabilization technique utilizing a Correlated Twirling protocol based on a unitary 2-design. By applying a synchronized, public twirling supermap, Alice and Bob mathematically transform deterministic, asymmetric geometric rotations into an isotropic Pauli depolarizing channel. Executed entirely as a virtual post-processing step during classical sifting, this protocol mathematically suppresses intrinsic channel noise by a factor of 2/3. We demonstrate through exact quantum state simulations that this induced symmetry neutralizes catastrophic axis-dependent failures, extending the Y-bias tolerance from 0.68 to 0.84 radians. Furthermore, the protocol passively extends the absolute angular misalignment tolerance for the 11% security threshold from $38.7^\circ$ to $47.9^\circ$, sustaining secure key distillation over extended fiber distances in highly turbulent regimes where standard architectures fail. Inherently compatible with decoy-state weak coherent pulses, this algorithmic approach provides a highly scalable, resource-efficient framework for robust long-distance quantum networks.

2605.07228 2026-05-11 quant-ph

Kochen-Specker nonlocal hidden variables must include time-ordering to allow for measurement independence of several agents

Valerio Scarani, Antoine Suarez

AI总结 本文研究了在涉及多个代理的贝尔型实验中,非定域隐变量理论的一致性问题。作者提出了一种本体论,其中上下文非定域隐变量以预存的可能性形式存在于时空之外的存储库中,并且每个代理可以自由选择上下文(测量独立性)。研究发现,为了使这种本体论在多代理实验中保持一致,上下文不仅需要包含可进行的测量,还必须包括不同代理选择的时间顺序。这一结果强调了时间序在实现测量独立性中的必要性。

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英文摘要

We consider an ontology, in which contextual nonlocal hidden variables are stored as pre-existing possibilities in a repository outside space-time; and in which the context can be chosen ``freely'' (measurement independence) by each agent, both in spacelike and timelike configurations. We show that, in Bell-type experiments involving several agents, for this ontology to be consistent, the context must include not only the measurements that can be performed, but also the time ordering of the choices of different agents.

2605.07227 2026-05-11 cond-mat.mtrl-sci

Physics Aware Representation Learning on Electronic Charge Density for Materials Property Prediction

Kammampati Sai Kumar, Albert Linda, Shubham Kumar Maurya, Somnath Bhowmick

AI总结 该研究提出了一种基于物理原理的深度学习框架,直接利用密度泛函理论(DFT)计算得到的三维电子电荷密度来预测材料的力学和热力学性质。通过三维卷积自编码器对高维电荷密度数据进行无监督降维,保留其物理意义特征,并结合组成描述符进一步提升预测精度。实验表明,该方法在多个材料性质预测任务上表现出色,如体积模量、杨氏模量和形成能等,且计算资源消耗仅为完整DFT计算的1/25。

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英文摘要

The fundamental quantity governing the mechanical and thermodynamic properties of a crystalline solid is its electronic charge density. Yet, its direct use for the rapid prediction of materials properties remains challenging due to its high dimensionality. Here, we present a physics-informed deep learning framework that directly predicts mechanical and thermodynamic properties from the three-dimensional electronic charge density derived from density functional theory (DFT). The proposed approach first utilizes a three-dimensional convolutional autoencoder for unsupervised dimensionality reduction, compressing a high-resolution charge-density grid (128 x 128 x 128) into a compact latent representation (16 x 16 x 16 x 16) while preserving physically meaningful features, as confirmed by negligible reconstruction errors across diverse crystal systems. The compressed latent-space representation of charge density is then used by two different regression models for property prediction: Light Gradient Boosting Machine (LightGBM) and Attention-based 3D Convolutional Neural Networks (Att CNN), and their performance is compared. Combining composition-based descriptors (Material Agnostic Platform for Informatics and Exploration or MAGPIE) with electronic charge density data further improves the model accuracy. Using a dataset of about 6059 inorganic compounds spanning multiple crystal symmetries, the models achieve strong predictive performance for bulk modulus K (R2 = 0.94), Young's modulus E (R2 = 0.88), shear modulus G (R2 = 0.87), formation energy Eform (R2 = 0.96), and Debye temperature Θ (R2 = 0.89). This work establishes electronic charge density as a transferable, physics-grounded descriptor for materials property prediction, requiring ~ 1/25 the computational resources of full-fledged DFT calculations.

2605.07226 2026-05-11 math.FA

Octonionic isometric isomorphisms and partial isometry

Qinghai Huo, Guangbin Ren, Zhenghua Xu

AI总结 本文研究了八元数函数分析中关于拟线性映射和弱关联正交基的新概念,并探讨了八元数拟线性等距算子的性质。研究发现,八元数希尔伯特双模上的拟线性算子为等距同构当且仅当它将任何关联正交基映射为弱关联正交基,并进一步引入了拟线性部分等距算子的概念,建立了相应的等价性结果。这些成果为理解八元数Stiefel空间提供了新的视角,拓展了相关理论的研究方向。

Comments 25pages

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英文摘要

Very recently, two new notions of para-linear mappings and weak associative orthonormal bases were introduced in octonionic functional analysis, which have been proved to be powerful in formulating the basic theory, such as the Riesz representation theorem and the Parseval theorem. In this article, we continue exploring more properties of these two concepts and initiate the study of octonionic para-linear isometric operators. Surprisingly, it is proven that the condition of the para-linear operator on a Hilbert octonionic bimodule being an isometric isomorphism is equivalent to it mapping any associative orthonormal basis to a weak associative orthonormal basis, which implies also that an octonionic matrix is an isometry if and only if the system of its row vectors is a weak associative orthonormal basis. Furthermore, we introduce the concept of para-linear partial isometric operators and establish the aforementioned analogue in this new setting. Based on these facts, we can provide naturally a new viewpoint of James questions by modifying the definition of octonionic Stiefel space.

2605.07225 2026-05-11 stat.AP

Spatiotemporal dynamics of wind-speed volatility

Ariane Nidelle Meli Chrisko, Philipp Otto

AI总结 本文研究了风速波动的时空动态特性,利用意大利北部141个站点2016至2021年的每日10米和100米高度风速观测数据,分析了其时空依赖性。研究采用基于GARCH类型的简洁时空波动模型,将条件方差与过去局部冲击及邻近站点的空间信息相结合,并结合基于距离和方向的权重矩阵构建结构化波动模型。结果表明,合理建模空间均值对残差行为和推断可靠性至关重要,且风速波动随高度增加而增强,多变量扩展揭示了不同高度间的相互依赖关系。

Comments Submitted to Environmetrics. 6 figures, 11 tables

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英文摘要

Wind-speed processes exhibit substantial temporal variability and spatial dependence, yet volatility dynamics across monitoring networks remain relatively unexplored. This study investigates the spatiotemporal behaviour of wind-speed volatility using daily observations from 141 stations in Northern Italy over 2016--2021, with measurements at 10 m and 100 m enabling the analysis of spatial and vertical dependence. We adopt a parsimonious spatiotemporal volatility framework based on GARCH-type dynamics, in which conditional variance depends on past local shocks and spatially aggregated information from neighbouring stations. The approach combines a spatial mean specification with structured volatility models using distance-based and directionally informed weight matrices. Results show that properly modelling spatial dependence in the mean is essential for well-behaved residuals and reliable inference. Forecast performance is strongly driven by the mean specification: flexible structures perform better when residual spatial dependence remains, while parsimonious distance-based models yield robust out-of-sample forecasts once spatial interactions are captured. Persistence increases with height, and a multivariate extension reveals cross-height dependence.

2605.07224 2026-05-11 gr-qc

Traversable wormholes in $\boldsymbol{f(Q)}$ gravity: Energy conditions, stability and quasinormal modes

Jaydeep Goswami, Rupam Jyoti Borah, Umananda Dev Goswami

AI总结 本文在$f(Q)$引力框架下研究了静态球对称可穿越虫洞的解,采用幂律形式的$f(Q)=γ(-Q)^m$模型,并通过引入各向异性物质分布和状态方程得到了满足虫洞几何条件的解析形状函数。研究发现,该模型在$0 < m < 1/2$范围内对应类 quintessence 的能量状态,虫洞喉部附近存在能量条件的违反,但整体结构稳定,且各向异性应力在维持虫洞结构中起关键作用。通过动力学稳定性分析和准正常模计算,验证了该虫洞解在动力学上的稳定性,表明$f(Q)$引力能够有效调节所需物质内容,从而支持几何一致且稳定的可穿越虫洞存在。

Comments 28 pages, 21 figures

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英文摘要

We investigate static and spherically symmetric traversable wormhole solutions in the framework of $f(Q)$ gravity by considering a power-law model of the form $f(Q)=γ(-Q)^m$. By adopting an anisotropic matter distribution and imposing an equation of state relating the radial pressure and energy density, we obtain an analytic shape function that satisfies the geometric requirements for a traversable wormhole. The model parameter is constrained to $0<m<1/2$, corresponding to a quintessence-like regime with $-1<ω<-1/3$. The energy conditions are analyzed in detail, showing that violations of the null and weak energy conditions are unavoidable but remain localized near the wormhole throat. The anisotropy parameter is positive throughout the spacetime, indicating that repulsive anisotropic stresses play a key role in sustaining the wormhole. The equilibrium configuration is examined using the generalized Tolman-Oppenheimer-Volkoff (TOV) equation for both zero and logarithmic redshift functions, where a consistent force balance is achieved with anisotropic effects providing the dominant outward support. Dynamical stability is studied through scalar perturbations, leading to a Schrödinger-like wave equation with a single-peak effective potential. The quasinormal modes are computed using the sixth-order WKB method with Padé approximation. The resulting frequencies possess negative imaginary parts, indicating stable damping of perturbations. Time-domain simulations further confirm the stability of the solutions and show good agreement with the WKB results, with small deviations in the damping rates. Thus, these results establish that $f(Q)$ gravity admits traversable wormhole solutions that are geometrically consistent and dynamically stable, with $f(Q)$ gravity effects effectively regulating the required matter content.

2605.07223 2026-05-11 cond-mat.dis-nn physics.app-ph

A Hardware-aware Hopfield Network with a Nonlinear Memristor Array for Robust Associative Memory with Superlinear Capacity

Younghyun Lee, Hakseung Rhee, Unhyeon Kang, Seungmin Oh, Kyungmin Lee, Hyun Jae Jang, Seongsik Park, YeonJoo Jeong, Inho Kim, Jong Keuk Park, Kyung Min Kim, Suyoun Lee

AI总结 该研究提出了一种面向硬件实现的霍普菲尔德网络(HHN),通过利用忆阻器的非线性电流-电压特性,优化网络的能量景观,从而显著提升联想记忆的存储容量。与传统和现代霍普菲尔德网络相比,HHN在保持能量最小化动态的同时,对噪声具有更强的鲁棒性,并且能够在固定突触预算下实现超线性的记忆容量增长。实验表明,该网络在高维图像数据上表现出优越的性能,为低功耗联想记忆和生成推理提供了一种可扩展的硬件原生架构。

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英文摘要

Associative memory retrieves complete patterns from partial or corrupted inputs and constitutes a primitive form of generative inference. Classical Hopfield networks (CHN) provide a canonical framework for associative memory but suffer from limited memory capacity. Recently, modern Hopfield networks (MHN) were introduced to achieve higher capacity by using explicit pattern-wise storage and neurons with the softmax activation function, which makes the MHN vulnerable to noise and the hardware implementation complicated due to its network size varying with the number of stored patterns. Here, we introduce a hardware-aware Hopfield network (HHN), in which the intrinsic nonlinear current-voltage characteristics of a charge-trap memristor are leveraged to engineer the energy landscape of the HN, increasing the memory capacity. Using a 25 x 25 nonlinear memristor array, we demonstrate reliable reconstruction of corrupted patterns with memory capacity far exceeding the classical limit (K ~ 0.14N, where N is the number of neurons). The HHN preserves Hopfield-type energy-minimization dynamics and remains robust to synaptic conductance noise. Large-scale simulations on high-dimensional image data reveal an empirical memory capacity scaling of K ~ 0.3 x N^1.2 under a fixed synaptic budget. These results establish HHN as a scalable hardware-native architecture for low-power associative memory and generative inference.

2605.07219 2026-05-11 physics.optics eess.SP

Perturbation-based Compensation with EEPN-free Phase Recovery as Back Propagation

Chuang Xu, Alan Pak Tao Lau

AI总结 本文提出了一种基于扰动的前馈方法,利用接收到的噪声信号补偿非线性失真,优于传统的基于判决的补偿方法且无需判决反馈。该方法结合无EEPN的载波相位恢复技术,通过全对称的传播-反向传播结构进一步提升了性能,为光通信系统中的非线性补偿提供了新的有效方案。

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We propose a feed-forward perturbation-based method that uses the noisy received signal to compensate for nonlinear distortion, which outperforms the conventional decision-based method and avoids decision feedback. Additionally, combining it with the EEPN-free carrier phase recovery shows additional gain due to a fully symmetrical propagation-backpropagation structure.

2605.07216 2026-05-11 gr-qc astro-ph.IM physics.geo-ph

Formulation of testing gravitational redshift based on Laser Time link between China Space Station and a ground station

Rui Xu, Wenbin Shen, Hok Sum Fok, Pengfei Zhang, Lihong Li, Lei Wang, Kuangchao Wu, An Ning, Youchao Xie, Ziyu Shen, Lingxuan Wang, Yongqi Zhao, Kai Liu, Yuanjin Pan

AI总结 本文提出了一种基于中国空间站与地面站之间激光时间传递系统的高精度引力红移检验方法,利用$c^{-3}$阶相对论模型构建了全面的观测方程。通过实际轨道数据模拟,实现了引力红移验证精度达$(1.8 \pm 47)\times 10^{-7}$,较以往实验提升了一个数量级,并首次在该精度下应用激光时间传递技术检验广义相对论的基本原理。该方法避免了电离层效应和一阶多普勒频移,为引力势差测量和大地测量应用提供了新的高精度手段。

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This paper presents a high-precision gravitational redshift test using the China Space Station (CSS) Laser Time Transfer (CLT) system. We develop a comprehensive observation equation based on a c^{-3} order relativistic model for space-ground clock comparison. While the CSS optical clock system is currently in the orbital debugging phase, our simulation using actual CSS orbit data achieves a gravitational redshift verification precision of (1.8 \pm 47)*10^{-7} -- approximately one order of magnitude improvement over previous experiments. Our work represents the first application of laser-based time transfer for gravitational redshift verification at such precision, and the first use of the CSS CLT link for testing this fundamental aspect of General Relativity. Unlike microwave-based methods, our laser approach avoids ionospheric effects and first-order Doppler shifts. Residual analysis identifies tropospheric delay variations and atmospheric turbulence as the primary remaining uncertainty contributors. The achieved precision enables gravitational potential difference measurements with 0.1 m^2/s^2 precision -- offering new capabilities for both fundamental physics investigations and geodetic applications including intercontinental height transfer. This work establishes a new benchmark for high-precision tests of relativistic physics and demonstrates the transformative potential of space-based optical time transfer.

2605.07207 2026-05-11 cs.NE

Direct-to-Event Spiking Neural Network Transfer

Nhan Trong Luu, Duong Trung Luu, Pham Ngoc Nam, Truong Cong Thang

AI总结 本文研究了如何将基于直接编码训练的脉冲神经网络(SNN)有效地转换为基于事件驱动的表示形式,以提高其能效。针对直接编码SNN在能量效率上的不足,作者系统分析了从直接编码向事件驱动转换过程中面临的关键挑战,并提出了一系列方法,在保持模型性能的同时实现高效的转换。该研究为提升SNN在能效敏感场景中的实用性提供了重要参考。

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Journal ref
IEEE Signal Processing Letters (2026)
英文摘要

Spiking Neural Networks (SNNs) have gained increasing attention due to their potential for low-power computation on neuromorphic hardware. A widely adopted training strategy for SNNs is direct coding, which enable backpropagation on neuron implementations using continuous-valued surrogate activations. However, recent studies have shown that direct-coded SNNs remain substantially less energy-efficient than their event-based counterparts, limiting their practical deployment in energy sensitive scenarios. Still, to promote the reusability of pretrained SNN database on direct code, this motivates an important yet underexplored question: How can a SNN pretrained with direct code be effectively converted into an event-based representation? In this research, we present the first systematic investigation into this transfer problem, analyze the key challenges that arise when transitioning from direct-coded to event-based computation and propose a set of methods to enable energy-efficient transfer while preserving model performance.

2605.07206 2026-05-11 cond-mat.mes-hall

Hybrid-order topology in two-dimensional nonsymmorphic antiferromagnets

Wei Xiong, Zi-Ming Wang, Xin-Mei Wei, Rui Wang, Dong-Hui Xu

AI总结 本文理论研究了二维非对称反铁磁体中的混合阶拓扑性质。通过引入具有动量依赖自旋密度波质量的反铁磁狄拉克模型,作者展示了单一的体绝缘态可以根据边界终止几何表现出不同阶的拓扑边界态:对于符合螺钉对称性的边界,存在无能隙的第一阶边缘态;而对于45度菱形终止边界,螺钉对称性被破坏,边缘态出现能隙,但磁镜对称性仍保护零维的角落态。该工作揭示了终止几何控制下第一阶与第二阶拓扑之间的对偶性,并为设计新型拓扑磁态提供了对称性指导。

Comments 5 pages, 4 figures, submitted to Phys. Rev. B

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英文摘要

We theoretically demonstrate hybrid-order topology in a two-dimensional nonsymmorphic antiferromagnet. Utilizing a generic antiferromagnetic Dirac model with a symmetry-allowed, momentum-dependent spin-density-wave (SDW) mass, we show that a single bulk insulating phase exhibits distinct topological boundary manifestations governed solely by the termination geometry. For screw-compatible edges, nonsymmorphic screw symmetry protects gapless first-order edge states. In contrast, for a $45^\circ$ diamond-shaped termination, the screw symmetry is broken at the boundary, resulting in gapped edges. However, the finite geometry still preserves magnetic mirror symmetries $\mathcal{M}_x\mathcal{T}$ and $\mathcal{M}_y\mathcal{T}$, which enforce an alternating pattern of edge masses, thereby binding zero-dimensional corner states. This second-order phase is characterized by a quantized quadrupole moment, with corner states pinned to zero energy by the chiral symmetry. We further demonstrate that explicit lattice perturbations can selectively gap the first-order edge modes while robustly preserving the corner states. Our work establishes a symmetry-based route to a termination-controlled duality between first- and second-order topology in magnetic nonsymmorphic systems.

2605.07205 2026-05-11 eess.SP

Omnidirectional Transponder for Narrow-band Radar Calibration

Oren Cohen, Moshe Vana

AI总结 本文提出了一种新型的频率转换转发器架构,用于解决合成孔径雷达(SAR)校准中传统参考目标体积大、视角受限的问题。该转发器实现了紧凑的一体化天线设计,具备全向操作能力,尽管其工作带宽受限,主要用于方位向校准,但在合成孔径内的脉冲间相位测量精度较高。实验验证表明,该转发器在圆周 SAR(CSAR)和双站 SAR 等需要全向参考目标的应用中具有重要应用潜力。

Comments Accepted to the 16th European Conference on Synthetic Aperture Radar (EUSAR 2026), June 8-11, 2026, Baden-Baden, Germany. 6 pages, 10 figures

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英文摘要

Conventional reference targets for Synthetic Aperture Radar (SAR) calibration, such as corner reflectors and standard transponders, are often inherently large and suffer from limited viewing angles. This paper presents a novel frequency-translating transponder architecture that circumvents these limitations, enabling a truly compact, single-antenna design capable of omnidirectional operation. While the operational bandwidth is consequently narrowed, restricting its use primarily to azimuth-direction calibrations, the design excels at providing highly accurate pulse-to-pulse phase measurements across the synthetic aperture. The transponder was prototyped and experimentally validated with a drone-mounted SAR. The results demonstrate the transponder's significant potential for applications requiring omnidirectional reference targets, such as Circular SAR (CSAR) and bistatic SAR.

2605.07200 2026-05-11 math.DG math.AP math.SP

The classical Weyl law for Schrödinger operators on complete Riemannian manifolds

Maxim Braverman, Xianzhe Dai, Junrong Yan

AI总结 本文研究了在完整黎曼流形上薛定谔算子 $H = Δ + V$ 的经典维约定律的成立条件。不同于以往依赖于有界几何或势函数的倍增条件等标准假设的方法,作者引入了一个几何与分析相结合的不变量 $c_δ(λ)$,用于刻画流形几何、势函数的增长速率及其振荡尺度之间的平衡关系。研究证明,当 $c_δ(λ)$ 随 $\lambda$ 趋于无穷时趋于零时,维约渐进行为成立,并通过具体例子验证了该条件的精确性。

Comments 35 pages, comments are welcome

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英文摘要

We establish a criterion for the validity of the classical (non-semiclassical) Weyl law for Schrödinger operators $ H=Δ+V $ on complete Riemannian manifolds. In contrast to existing results, our approach does not rely on standard geometric assumptions such as bounded geometry, nor on analytic assumptions such as the doubling condition on the potential. Instead, we identify a geometric-analytic invariant that encodes the precise balance between the geometry of the manifold, the growth of $V$, and the oscillation scale of $V$. This intrinsic quantity, denoted $c_δ(λ)$ admits effective quantitative estimates. We prove that the Weyl asymptotic holds provided $\lim_{λ\to\infty} c_δ(λ)=0 .$ The sharpness of this criterion is demonstrated through explicit examples showing that the Weyl law can fail when the criterion is violated.

2605.07198 2026-05-11 math.DS math.AP

Minimal speed of unbounded traveling wave solutions for a 1D reaction-diffusion equation and their relationship with the dynamics at infinity

Yu Ichida

AI总结 本文研究了一维反应扩散方程中无界行波解的最小速度及其与无穷远处动力学的关系,该方程具有渐近线性反应项和饱和参数。通过应用庞加莱型紧致化方法,揭示了行波解所满足的二维常微分方程系统的整体动力学(包括无穷远处的行为),从而获得了行波解的关键特性,包括相平面中轨迹的分类、前沿型和符号变化型解的正性和无界性,以及最小速度的显式表达。研究指出,最小速度由行波系统在无穷远处的信息决定,与传统线性决定性结果有所不同。

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英文摘要

This paper presents results on the unboundedness and minimal speed of traveling wave solutions for a one-dimensional spatial reaction-diffusion equation with an asymptotically linear reaction term and a saturation parameter. By applying a Poincaré-type compactification, we reveal the full dynamics (including infinity) of the two-dimensional system of ordinary differential equations satisfied by traveling wave solutions. This yields essential information characterizing traveling wave solutions: the classification of trajectories in the phase plane, the positivity and unboundedness of front-type and sign-changing profiles, and the explicit form of the minimal speed. This paper examines a special equation with an asymptotically linear reaction term. While, our results differ from those of conventional linear determinacy. We claim that the minimal speed is derived from information at infinity within the traveling wave system.

2605.07197 2026-05-11 physics.atom-ph

State-resolved electron capture in low-energy Ar2+-Ar/N2 collisions

Shucheng Cui, Dadi Xing, Xiaolong Zhu, Dongmei Zhao, Dalong Guo, Yong Gao, Shaofeng Zhang, Chenzhong Dong, Xinwen Ma

AI总结 本文研究了低能 Ar²⁺ 离子与 Ar 原子或 N₂ 分子碰撞过程中的单电子和双电子捕获动力学机制,旨在补充该领域的高精度实验数据。实验在中科院近代物理研究所的 EBIS 平台上进行,采用 COLTRIMS 技术重建反冲离子的三维动量分布,并结合理论模型进行对比分析,为多电子靶体系的电荷交换过程提供了重要的状态分辨实验依据。

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Journal ref
Acta Phys. Sin. 2025, 74(24):240702
英文摘要

As a fundamental process in atomic physics, charge exchange relies on quantum state-resolved data that is crucial for various fields such as astrophysics and plasma physics. However, there remains a g in the research on multi-electron target systems. This study aims to investigate the dynamic mechanisms of single/double electron capture in collisions between Ar2+ ions and Ar atoms or N2 molecules at an energy of 40 keV, thereby supplementing high-precision experimental data in this field. The experiment is conducted on the electron beam ion source (EBIS) platform at the Institute of Modern Physics, Chinese Academy of Sciences, using the cold target recoil ion momentum spectroscopy (COLTRIMS) technique. An ion beam containing ground-state Ar2+ (3s^2 3p^(4 3) P) and metastable Ar2+ (3s^2 3p^(4 1) D,(_^1)S) is used as the projectile, colliding with a supersonic Ar/ N2 mixed gas target. Three-dimensional momentum of recoil ions is reconstructed through coincidence measurements of recoil ions and scattered ions, and the Q-value and scattering angle distribution are calculated. Theoretical comparisons are performed using the molecular Coulombic over barrier model (MCBM).

2605.07196 2026-05-11 math.CO

Counterexamples to a conjecture on graph inertia

Hongzhang Chen, Jianxi Li

AI总结 本文研究图的惯性(inertia)问题,即图的邻接矩阵正、零、负特征值数量组成的三元组。作者针对Akbari等人提出的关于图惯性的一个猜想,构造了一类反例图$W_k$($k\ge5$),其惯性为$\left(\binom{k}{2}+1,\ 0,\ k-1\right)$,从而推翻了该猜想。此外,作者还通过删除$W_5$中的一个顶点,得到了惯性为$(10,0,4)$的图,解决了该论文中提出的一个问题,并否定了其中提出的较弱不等式。

Comments 9 pages. Any comments and suggestions are welcome

详情
英文摘要

The inertia of a graph $G$ is $\operatorname{In}(G)=(n^+(G),n^0(G),n^-(G))$, where $n^+(G),\, n^0(G),\, n^-(G)$ are the numbers of positive, zero and negative eigenvalues of the adjacency matrix of $G$, respectively, counted with multiplicities. Akbari, Elphick, Kumar, Pragada and Tang [Discrete Math. 349 (2026) 114953] conjectured that every graph $G$ satisfies \[ 2n^+(G)\le n^-(G)(n^-(G)+1). \] In this note, we construct a family of reduced graphs $\{W_{k}:\,k\ge5\}$ with \[ \operatorname{In}(W_k) = \left(\binom{k}{2}+1,\ 0,\ k-1\right), \] each of which violates the conjectured inequality. We also observe that deleting the vertex $a_1$ from $W_5$ gives a reduced graph with inertia $(10,0,4)$, answering a question raised in the same paper. The family also refutes a weaker inequality proposed there.

2605.07187 2026-05-11 gr-qc

Probing Gravitational Wave Signatures from Periodic Orbits of Regular Black Holes in Asymptotically Safe Gravity

Arun Kumar, Abolhassan Mohammadi, Sushant G. Ghosh

AI总结 本文研究了渐近安全引力理论中正则黑洞的束缚和周期类时测地线及其相关的引力波特征。通过引入量子修正参数 $ξ$,修改了黑洞视界附近的几何结构,同时保持渐近平坦性,并利用拓扑分类和频率比分析了周期轨道的特性。研究发现,随着 $ξ$ 的增大,引力波信号表现出可检测的振幅调制和相位偏移,其特征频率位于空间引力波探测器的灵敏范围内,为通过观测极端质量比吸积系统中的轨道动力学限制量子引力效应提供了可能。

Comments 14 pages, 13 figures, 1 table

详情
英文摘要

We investigate bound and periodic timelike geodesics and their associated gravitational-wave (GW) signatures in the spacetime of a regular black hole arising in asymptotically safe gravity (ASG). The geometry incorporates quantum corrections via a running gravitational coupling, encoded in a dimensional scaling parameter $ξ$, that modifies the near-horizon structure while preserving asymptotic flatness. We derive the effective potential for massive test particles and determine the conditions for stable circular and bound motion as functions of $ξ$, including the shift in the innermost stable circular orbit (ISCO). The three topological integers $(z,w,v)$, which represent the number of zooms, whirls, and vertices per radial cycle, are used to categorize the test particles' periodic orbits using Levin's zoom -- whirl taxonomy. Moreover, we employ the rational frequency ratio $q = \frac{ω_ϕ}{ω_r} - 1$ to find closed orbits, where $ω_ϕ$ and $ω_r$ stand for the azimuthal and radial frequencies, respectively. We examine how the orbital frequency spectrum is altered, whirl behaviour is enhanced, and deviations from the Schwarzschild limit are produced by the quantum parameter $ξ$. The GW forms for extreme mass-ratio inspirals (EMRIs) are calculated within the quadrupole approximation. We find that as $ξ$ increases, the signals that are released exhibit detectable amplitude modulations and phase shifts. The corresponding typical strain spectra fall within the anticipated sensitivity limits of space-based detectors such as LISA, Taiji, and TianQin, as they peak in the millihertz frequency band. Peak strain increases monotonically with $ξ$, indicating that observational restrictions on quantum-gravity-induced deviations from classical general relativity in the strong-field domain can be obtained from precise measurements of zoom -- whirl dynamics in EMRIs.