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2605.27143 2026-05-27 eess.SY cs.SY

Container Unloading via Reinforcement Learning: Picking Order, Deadlock Avoidance, and Proof-of-Concept Simulation

基于强化学习的集装箱卸载:拣选顺序、死锁避免及概念验证仿真

Jan Rüdiger, Max Schenke, Daniel Weber

AI总结 针对快递包裹行业集装箱卸载的自动化需求,提出一种基于掩码深度Q学习与特殊神经网络架构的策略,在仿真环境中实现平均60%的成功率,显著优于随机策略的20%。

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AI中文摘要

在快递、快运和包裹行业中,卸载集装箱是一项体力要求高且劳动密集型的工作。自动化这一过程是提高包裹处理系统效率的重要一步。本研究探讨了强化学习在集装箱卸载场景中学习物品选择策略的潜力。为此,创建了一个仿真环境,并实现了一种具有特殊设计的神经网络架构的掩码深度Q学习。结果表明,智能体能够以平均60%的成功率学习选择物品,这显著优于随机策略的20%随机概率。研究结果表明,强化学习可能是未来自动化物品卸载任务的一种有前景的方法。

英文摘要

Unloading containers in the courier, express and parcel industry is a physically demanding and labor-intensive work. Automatizing this process is an important step towards increasing the efficiency of parcel-handling systems. This work investigates the potential of reinforcement learning to learn a policy for item selection in container unloading scenarios. For that, a simulation environment is created and a masked deep Q-learning with a specially designed neural network architecture is implemented. The results indicate that the agent can learn to select items with an average success rate of 60 %, which is significantly better than a random policy at a random chance of 20 %. The findings suggest that RL could be a promising approach for automatizing item unloading tasks in the future.

2605.27142 2026-05-27 physics.chem-ph

Dyck language and fermionic second quantization: I. Theory

Dyck语言与费米子二次量子化:I. 理论

Jérémy Morere, Thibaud Etienne

AI总结 本文提出一个连接费米子二次量子化与Dyck语言的新框架,通过用括号字母表定义产生和湮灭算符的翻译,建立二次量子化算符链期望值的零性判据,并引入Dyck语言的深度概念以扩展零性判据。

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AI中文摘要

本文提出了一个连接费米子二次量子化与Dyck语言的新框架。通过使用括号字母表定义产生和湮灭算符的翻译,研究建立了二次量子化算符链期望值的零性判据。这些翻译旨在揭示相对于单行列式态或物理真空的期望值为零的充分条件。零性判据是纯句法的,只需检查开闭括号序列。此外,Dyck语言中的数字和变换可以引入费米子二次量子化中。其中一个数字——深度,原本在二次量子化中不存在,可用于引入更多的零性判据。

英文摘要

This paper proposes a novel framework connecting fermionic second quantization and Dyck languages. By defining translations of creation and annihilation operators using bracket alphabets, the study establishes nullity criteria for expectation values of chains of second quantization operators. Those translations are designed to reveal sufficient conditions for the nullity of the expectation values relatively to one-determinant states or to the physical vacuum. The nullity criteria are purely syntactic, and simply reduce to the inspection of sequences of opening and closing brackets. Moreover, numbers and transformations in Dyck languages can be imported in the context of fermionic second quantization. One of these numbers, the depth, originally absent from second quantization, can be used to introduce more nullity criteria.

2605.27137 2026-05-27 math.ST stat.ME stat.TH

Bernstein-von Mises Theorem for Sparse Generalized Linear Model

稀疏广义线性模型的 Bernstein-von Mises 定理

Hanqing Li, Xuewen Lu

AI总结 研究广义线性模型中的 spike-and-slab 先验,通过分数后验的 oracle Bernstein-von Mises 定理,在支撑似然假设下实现收缩、支撑恢复和高斯混合近似。

Comments 99 pages

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AI中文摘要

我们研究了广义线性模型中具有可能分组稀疏性的 spike-and-slab 先验。主要结果是分数后验在支撑似然假设下的 oracle Bernstein--von Mises 定理。证明发展了稀疏局部渐近正态性和围绕支撑特定伪真实中心的 Laplace 近似,并将其与固定先验质量、支撑惩罚、恢复几何和 beta-min 分离相结合,以获得收缩、支撑恢复、高斯混合近似以及向 oracle 高斯律的坍缩。在所述充分条件下,对高斯回归以及逻辑回归、泊松回归、probit 回归、Gamma 对数链接回归和负二项对数链接回归给出了模型条目验证。普通后验仅通过受限高斯和典型链接扩展进行处理,并在额外的活跃维度和矩条件下覆盖。

英文摘要

We study spike-and-slab priors for generalized linear models with possible grouped sparsity. The main result is an oracle Bernstein--von Mises theorem for the fractional posterior under supportwise likelihood assumptions. The proof develops sparse local asymptotic normality and Laplace approximation around support-specific pseudo-true centers, and combines them with fixed-prior mass, support penalization, recovery geometry, and beta-min separation to obtain contraction, support recovery, Gaussian mixture approximation, and collapse to the oracle Gaussian law. Model-entry verifications are given for Gaussian regression and for logistic, Poisson, probit, Gamma log-link, and negative-binomial log-link regression under stated sufficient conditions. The ordinary posterior is treated only through restricted Gaussian and canonical-link extensions, with coverage under additional active-dimension and moment conditions.

2605.27127 2026-05-27 cond-mat.mtrl-sci physics.optics

Light-induced Faraday effect from dynamical breakdown of Kleinman symmetry

Kleinman对称性动态破缺引起的光致法拉第效应

Niccolò Sellati, Jacopo Fiore, Lara Benfatto

AI总结 本文通过研究三阶光学磁化率的反对称分量,揭示了光致法拉第效应源于Kleinman对称性破缺,无需宏观磁化即可产生静态偏振旋转,并利用紧束缚模型和声子耦合展示了其显著增强。

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AI中文摘要

最近,在圆偏振光的泵浦-探测实验中观测到异常大的偏振旋转,挑战了逆法拉第效应的传统理解。这些响应的惊人幅度意味着产生了比理论预期大数个数量级的有效磁场,引发了关于光致时间反演对称性破缺本质的基本问题。在这项工作中,我们证明静态偏振旋转可以完全源自三阶光学磁化率的反对称分量,而无需产生材料的宏观磁化。我们表明,这种光致法拉第效应本质上是动态的,在Kleinman对称性破缺时出现。使用正方晶格上的最小sp紧束缚模型,我们证明即使在远离耗散共振的情况下,光致法拉第响应也可能相当可观。虽然该效应出现在纯电子层面,但我们表明与声子的共振耦合可以显著增强泵浦-探测响应。

英文摘要

The observation of anomalously large polarization rotations in pump-probe experiments with circularly polarized light has recently challenged the conventional understanding of the inverse Faraday effect. The striking magnitude of these responses implies the generation of effective magnetic fields orders of magnitude larger than theoretical expectations, raising fundamental questions about the nature of light-induced time-reversal symmetry breaking. In this work we demonstrate that a static polarization rotation can originate entirely from the antisymmetric component of the third-order optical susceptibility, without generating a macroscopic magnetization of the material. We show that this light-induced Faraday effect is inherently dynamical, emerging when Kleinman symmetry breaks down. Using a minimal sp tight-binding model on a square lattice, we demonstrate that the light-induced Faraday response can be sizable even far from dissipative resonances. While the effect emerges at a purely electronic level, we show that resonant coupling with phonons can significantly enhance the pump-probe response.

2605.27126 2026-05-27 math.GT math.SG

A contact version of Kirby's theorem

Kirby定理的接触版本

Marc Kegel, Eric Stenhede, Vera Vértesi

AI总结 本文引入灯笼移动和链移动两类新的接触Kirby移动,结合已知移动,给出完整的接触Kirby移动集,证明两个接触手术图表示接触同胚的接触流形当且仅当它们可通过一系列平面同位素、Legendrian Reidemeister移动、标准取消对的插入或移除、两种标准接触柄滑动、标准灯笼移动和标准链移动相互转换。

Comments 46 pages, 58 figures; comments are welcome

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AI中文摘要

Ding和Geiges的一个定理指出,每个闭连通接触$3$-流形都可以通过沿Legendrian链环的接触$(\pm1)$-手术从标准紧接触$3$-球面得到。文献中也包含一些接触Kirby移动的例子,即对Legendrian手术链环的前投影进行显式操作,这些操作改变手术链环但保持手术流形的接触同胚类型。其中最常用的是取消对和接触柄滑动;然而,仅靠这些移动不足以关联所有接触同胚接触流形的接触手术图。 在本文中,我们引入了两类新的接触Kirby移动,称为灯笼移动和链移动,并用它们给出了完整的接触Kirby移动集。更精确地说,我们证明两个接触手术图表示接触同胚的接触流形当且仅当它们可通过一系列平面同位素、Legendrian Reidemeister移动、标准取消对的插入或移除、两种标准接触柄滑动、标准灯笼移动和标准链移动相互转换。所有这些移动都是前投影中的显式图解操作。 证明遵循Avdek通过其ribbon-move框架发起的方法,该方法植根于Giroux对应,并结合了Gervais对映射类群的表示。我们还讨论了主定理的几个推论,通过纯粹图解方式恢复Gompf的$d_3$-不变量不变性,并通过接触几何方法推导拓扑Kirby定理,说明了接触Kirby演算的有效性。

英文摘要

A theorem of Ding and Geiges states that every closed, connected contact $3$-manifold can be obtained from the standard tight contact $3$-sphere by contact $(\pm1)$-surgery along a Legendrian link. The literature also contains some examples of contact Kirby moves, i.e. explicit operations on front projections of Legendrian surgery links that change the surgery link but preserve the contactomorphism type of the surgered manifold. Among the most commonly used are cancelling pairs and contact handle slides; however, these moves alone are not sufficient to relate all contact surgery diagrams of contactomorphic contact manifolds. In this article, we introduce two new families of contact Kirby moves, called lantern moves and chain moves, and use them to give a complete set of contact Kirby moves. More precisely, we show that two contact surgery diagrams represent contactomorphic contact manifolds if and only if they are related by a sequence of planar isotopies, Legendrian Reidemeister moves, insertions or removals of standard cancelling pairs, the two standard contact handle slides, the standard lantern move, and the standard chain move. All these moves are explicit diagrammatic operations in the front projection. The proof follows an approach initiated by Avdek through his ribbon-move framework, which is rooted in the Giroux correspondence, and combines it with a presentation by Gervais of the mapping class group. We also discuss several consequences of the main theorem, illustrating the effectiveness of the contact Kirby calculus by recovering the invariance of Gompf's $d_3$-invariant purely diagrammatically and by deriving the topological Kirby theorem from contact-geometric methods.

2605.27125 2026-05-27 gr-qc

Diffeomorphism-Like Symmetry in Gravitoelectromagnetism

引力电磁学中的微分同胚类对称性

L. A. S. Evangelista, A. F. Santos

AI总结 研究Weyl形式下的引力电磁学,通过分析受限规范对称性对张量场A_{μν}的影响,推导传播子并揭示自旋2、自旋1和标量自旋0扇区的贡献,证明只有自旋2和标量扇区对物理过程有贡献,并扩展规范对称性至费米子和电磁扇区。

Comments 27 pages

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AI中文摘要

通过分析受限规范对称性对张量场$A_{μν}$的影响,研究了Weyl形式下的引力电磁学。明确推导了与GEM场相关的传播子,并在Barnes-Rivers形式下进行分解,揭示了自旋-2、自旋-1和标量自旋-0扇区的贡献。通过将理论与守恒源耦合,证明只有自旋-2和标量扇区对物理过程有贡献,而自旋-1分量解耦。得到的有效传播子可以写成紧凑的度量形式,与线性化广义相对论的引力子传播子非常相似。还通过考虑类洛伦兹和de Donder型规范条件分析了规范固定的作用。结果表明,类洛伦兹规范与理论的受限规范对称性一致,并导致规范无关的物理振幅,而de Donder规范引入了残余的规范依赖标量贡献,表明与底层对称结构不相容。通过微分同胚类变换,将规范对称性进一步扩展到费米子和电磁扇区。在两种情况下,推导了守恒流,并证明它们与相应的能量-动量张量一致,意味着GEM场与物质的耦合方式与线性化引力相同。最后,验证了相关的Ward恒等式,为理论的规范结构和相互作用顶点提供了非平凡的相容性检验。

英文摘要

Gravitoelectromagnetism in the Weyl formalism is investigated through an analysis of the consequences of a restricted gauge symmetry acting on the tensor field $A_{μν}$. The propagator associated with the GEM field is explicitly derived and decomposed within the Barnes--Rivers formalism, revealing contributions from the spin-2, spin-1, and scalar spin-0 sectors. By coupling the theory to conserved sources, it is shown that only the spin-2 and scalar sectors contribute to physical processes, while the spin-1 component decouples. The resulting effective propagator can then be written in a compact metric form closely resembling the graviton propagator of linearized General Relativity. The role of gauge fixing is also analyzed by considering both Lorentz-like and de Donder-type gauge conditions. It is shown that the Lorentz-like gauge is consistent with the restricted gauge symmetry of the theory and leads to gauge-independent physical amplitudes, whereas the de Donder gauge introduces residual gauge-dependent scalar contributions, signaling an incompatibility with the underlying symmetry structure. The gauge symmetry is further extended to the fermionic and electromagnetic sectors through diffeomorphism-like transformations. In both cases, conserved currents are derived and shown to coincide with the corresponding energy-momentum tensors, implying that the GEM field couples to matter in the same manner as in linearized gravity. Finally, the associated Ward identities are verified, providing a nontrivial consistency check of the gauge structure and interaction vertices of the theory.

2605.27124 2026-05-27 cs.PL cs.SE

ProDebug: An Automated Debugging System for Prolog

ProDebug:Prolog的自动化调试系统

Ricardo Brancas, Vasco Manquinho, Ruben Martins

AI总结 提出结合大语言模型、频谱和变异技术的Prolog自动调试系统ProDebug,用于识别学生作业中的错误并生成修复方案。

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AI中文摘要

Prolog是一种著名的声明式编程语言,常用于逻辑与推理入门课程。然而,许多学生发现Prolog具有挑战性,因为它缺乏命令式语言中常见的调试机制。在大班教学中,这一困难因提供及时个性化反馈的挑战而加剧。在这项工作中,我们介绍了ProDebug,这是首个将大语言模型(LLMs)与基于频谱和基于变异的技术相结合,用于Prolog作业自动调试的工具。ProDebug自动识别错误并为学生的Git提交提出错误修复。错误检测使用三种方法——基于频谱、基于变异和LLM推理——而修复则使用基于变异的技术和LLMs生成。我们对来自本科编程课程的1499个有错误的学生提交进行了评估,展示了自动化、LLM增强的反馈系统在扩展声明式编程教育支持方面的潜力。

英文摘要

Prolog is a well-known declarative programming language commonly used in introductory courses on logic and reasoning. However, many students find Prolog challenging because it lacks the familiar debugging mechanisms found in imperative languages. In large classes, this difficulty is exacerbated by the challenge of providing timely and personalized feedback to students. In this work, we introduce ProDebug, the first tool to combine Large Language Models (LLMs) with spectrum-based and mutation-based techniques for automated debugging of Prolog assignments. ProDebug automatically identifies faults and proposes bug repairs for student Git submissions. Faults are detected using three approaches--spectrum-based, mutation-based, and LLM reasoning--while repairs are generated using mutation-based techniques and LLMs. Our evaluation on 1499 buggy student submissions from a bachelor's level programming class demonstrates the potential of automated, LLM-augmented feedback systems to scale support for declarative programming education.

2605.27123 2026-05-27 cs.IR

Rethinking Agentic RAG: Toward LLM-Driven Logical Retrieval Beyond Embeddings

重新思考智能体RAG:迈向超越嵌入的LLM驱动逻辑检索

Yuqi Zeng, Qixiang Deng, Yulei Wan, Ruiquan Jiang, Xiaoqing Zheng, Xuanjing Huang

AI总结 提出一种智能体RAG框架,让LLM通过逻辑表达式控制检索,使用轻量级倒排索引后端,在降低成本和幻觉的同时匹配强基线性能。

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AI中文摘要

近期RAG的进展转向智能体范式,其中LLM与检索系统进行多轮交互,并根据中间结果迭代优化查询。同时,LLM已展现出构建结构化查询以精确表达信息需求的强大能力。然而,当代RAG系统仍主要专注于设计复杂的检索后端,包括密集、混合和基于图的检索架构。在本研究中,我们认为智能体RAG应赋予LLM更多控制权来引导检索过程,同时依赖一个提供细粒度控制并忠实执行LLM结构化意图的轻量级检索接口。基于这一原则,我们提出一个智能体RAG框架,使LLM能够使用逻辑表达式制定检索意图,同时将检索后端简化为基于倒排索引的系统。大量实验表明,我们的框架与强大的智能体混合基线性能相当,同时大幅降低了构建和服务成本。此外,我们证明将检索过程锚定在逻辑查询上可显著减少生成响应中的幻觉。

英文摘要

Recent advances in RAG have shifted toward an agentic paradigm, where LLMs interact with retrieval systems over multiple turns and iteratively refine queries based on intermediate results. At the same time, LLMs have demonstrated a strong ability to construct structured queries that precisely express their information needs. However, contemporary RAG systems remain heavily focused on engineering complex retrieval backends, including dense, hybrid, and graph-based retrieval architectures. In this study, we argue that agentic RAG should delegate greater control to the LLM to steer the retrieval process, while relying on a lightweight retrieval interface that provides fine-grained control and faithfully executes the LLM's structured intent. Guided by this principle, we propose an agentic RAG framework that enables LLMs to formulate retrieval intents using logical expressions while simplifying the retrieval backend to an inverted-index-based system. Extensive experiments show that our framework matches a strong agentic hybrid baseline, while substantially reducing construction and serving cost. Moreover, we show that anchoring the retrieval process in logical queries substantially reduces hallucinations in generated responses.

2605.27122 2026-05-27 math.SG

Open Gromov-Witten invariants in genus zero and Lagrangian cobordisms

亏格零的开放Gromov-Witten不变量与Lagrangian配边

Amanda Hirschi, Kai Hugtenburg

AI总结 针对任意闭辛流形和嵌入的相对自旋Lagrangian子流形,利用边界上链构造了亏格零的开放Gromov-Witten不变量,证明了开放WDVV关系及其对近复结构和Hamilton同痕的无关性,并建立了配边Lagrangian之间的不变量关系。

Comments 33 pages, no figures, comments welcome!

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AI中文摘要

我们为任意闭辛流形和嵌入的相对自旋Lagrangian子流形构造了亏格零的开放Gromov-Witten不变量,这些子流形通过边界上链是弱无阻碍的。这基于\cite{HH25,HH26}的基础工作和\cite{ST21}的代数框架。我们证明了开放WDVV关系,并表明这些不变量独立于近复结构的选择且在Hamilton同痕下不变。我们还证明了配边Lagrangian的开放Gromov-Witten不变量之间的关系。

英文摘要

We construct open Gromov-Witten invariants in genus zero for arbitrary closed symplectic manifolds and embedded relatively spin Lagrangians, which are weakly unobstructed by a bounding cochain. This uses the foundational work of \cite{HH25,HH26} and the algebraic framework of \cite{ST21}. We prove the open WDVV relations and show that these invariants are independent of the choice of almost complex structure and under Hamiltonian isotopy. We also prove a relation between open Gromov-Witten invariants of cobordant Lagrangians.

2605.27121 2026-05-27 hep-ph

Refined extraction of electroweak and nuclear parameters from germanium CE$ν$NS data

从锗CE$ν$NS数据中精细提取电弱和核参数

Valentina De Romeri, Laura Duque, Dimitrios K. Papoulias, G. Sanchez Garcia, Christoph A. Ternes

AI总结 联合分析COHERENT和CONUS+实验的CE$ν$NS数据,利用互补性提高锗中子半径和弱混合角的提取精度,并评估核淬灭因子和核结构不确定性的影响。

Comments 16 pages, 5 figures

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AI中文摘要

我们提出了对来自两个互补实验(COHERENT和CONUS+)的锗上近期CE$ν$NS数据的联合分析。COHERENT使用π介子静止衰变产生的中微子,CONUS+探测反应堆反中微子。利用这两个数据集的互补性进行联合统计分析,我们以改进的精度提取了锗的均方根中子半径和中子皮,解耦了谱形畸变与整体归一化,并减少了系统不确定性。我们还确定了低动量转移下的弱混合角,为在较少探索的运动学区域检验标准模型提供了测试。CE$ν$NS电离测量中的一个关键系统不确定性是核淬灭因子;因此,我们以Lindhard模型变化函数的形式呈现结果。对于核形状因子,我们采用解析的Klein-Nystrand参数化,并将其与大规模核壳模型预测进行基准比较,评估核结构不确定性对我们结果的影响。我们的分析展示了结合不同中微子源数据集以最大化对核物理和电弱物理敏感性的能力。

英文摘要

We present a combined analysis of recent CE$ν$NS data on germanium from two complementary experiments: COHERENT, which uses neutrinos from pion decay at rest, and CONUS+, which detects reactor antineutrinos. Exploiting the complementarity of these two datasets in a joint statistical analysis, we extract the germanium root-mean-square neutron radius and neutron skin with improved precision, disentangling spectral shape distortions from overall normalizations and reducing systematic uncertainties. We also determine the weak mixing angle at low momentum transfer, providing a test of the Standard Model in a less-explored kinematic regime. A key systematic uncertainty in CE$ν$NS ionization measurements is the nuclear quenching factor; we therefore present our results as a function of variations of the Lindhard model. For the nuclear form factor, we adopt the analytical Klein-Nystrand parametrization and benchmark it against predictions from the large-scale nuclear Shell Model, assessing the impact of nuclear structure uncertainties on our results. Our analysis demonstrates the power of combining datasets across different neutrino sources to maximize sensitivity to both nuclear and electroweak physics.

2605.27120 2026-05-27 stat.ME

Copula and spatial-regularized variational autoencoder for mapping disease comorbidity in West Africa

Copula与空间正则化变分自编码器用于西非疾病共病映射

Osafu Augustine Egbon, Bassey David Ita, Faith Eshofonie, Ezra Gayawan

AI总结 提出一种结合双变量Gumbel copula和空间正则化的变分自编码器,用于建模西非儿童腹泻、发烧和急性呼吸道感染共病的空间异质性和非对称依赖关系,并识别高风险区域及风险因素。

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AI中文摘要

地理空间健康不均衡仍然是一个关键的公共卫生问题,因为社区由于暴露于不同的不利社会经济和环境条件而面临异质性的疾病风险。尽管已采用统计模型来识别风险因素,但考虑共病模式中固有的复杂非线性依赖和空间规律性的研究尚不充分。在这项工作中,我们提出了一种新颖的空间正则化变分自编码器(VAE),用于表征和映射西非儿童共病的地理空间不均衡,重点关注腹泻、发烧和急性呼吸道感染(ARI)。为了模拟这些疾病之间的依赖性,本研究将双变量Gumbel copula集成到VAE框架中,从而能够灵活建模非对称依赖性并量化联合和条件发病风险。此外,框架内的协变量效应被量化,以促进风险因素的流行病学解释。所提出的方法与常用方法进行了基准比较,并应用于使用人口与健康调查数据表征西非的共病情况。结果显示,西非儿童共病可能性存在显著的空间异质性,其中发烧和ARI之间的共现最强。家庭财富、母亲教育程度和改善水源的可及性与共病可能性相关。这些模式突出了高风险区域,并强调了需要有针对性的、特定地点的公共卫生干预措施。

英文摘要

Geospatial health disproportionality remains a critical public health concern, as communities face heterogeneous illness risks due to varying exposures to adverse socioeconomic and environmental conditions. While statistical models have been adopted to identify risk factors, studies that account for the complex, non-linear dependencies and spatial regularities inherent in comorbid disease patterns are underdeveloped. In this work, we propose a novel spatially regularized variational autoencoder (VAE) to characterize and map the geospatial disproportion of childhood comorbidity in West Africa, focusing on diarrhea, fever, and acute respiratory infection (ARI). To model dependence between these conditions, this study integrates a bivariate Gumbel copula into the VAE framework, enabling flexible modeling of asymmetric dependence and quantification of joint and conditional morbidity risks. Additionally, covariate effects within the framework were quantified to facilitate epidemiological interpretation of risk factors. The proposed method was benchmarked against commonly used methods and applied to characterize comorbidity in West Africa using the Demographic and Health Survey data. Findings reveal pronounced spatial heterogeneity in the likelihood of comorbidity among West African children, with the strongest co-occurrence observed between fever and ARI. Household wealth, maternal education, and access to improved water sources were associated with the likelihood of comorbidity. These patterns highlight high-risk areas and underscore the need for targeted, location-specific public health interventions.

2605.27119 2026-05-27 math.AP math.CA math.FA

A Counterexample to Kenig's Interpolation Problem for Sobolev Spaces with Zero Boundary Conditions

Kenig关于零边界条件Sobolev空间插值问题的反例

Xiaosheng Lin, Dachun Yang, Sibei Yang, Wen Yuan, Yangyang Zhang

AI总结 本文构造了一个有界C^1区域Ω,证明当s∈(1,2)\setminus{3/2}时插值空间相等,但s=1/2时真包含,从而给出Kenig问题3.3.19的反例,并应用于Dirichlet Laplacian的定义域和热方程解的正则性。

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AI中文摘要

设$n\in \mathbb N\cap[2,\infty)$。在本文中,我们证明存在一个有界$C^1$区域$\Omega\subset \mathbb R^n$,使得对任意给定的$s\in(1,2)\setminus\{\frac32\}$,有\begin{align*} \left[H_0^1(\Omega),H^2(\Omega)\cap H_0^1(\Omega)\right]_{s-1} =H^s(\Omega)\cap H_0^1(\Omega)=H_0^s(\Omega) \end{align*}且范数等价,但\begin{align*} \left[H_0^1(\Omega),H^2(\Omega)\cap H_0^1(\Omega)\right]_{\frac12} \subsetneqq H^{\frac32}(\Omega)\cap H_0^1(\Omega), \end{align*}这为Kenig在[CBMS Regional Conf. Ser. in Math. 83, 1994]中的问题3.3.19提供了一个反例。作为应用,我们证明对这样的区域$\Omega$有\begin{align*} H^2(\Omega)\cap H_0^1(\Omega)\subsetneqq D(-\Delta_D) \end{align*}(Dirichlet Laplacian算子$-\Delta_D$在$\Omega$上的定义域),并构造了一个具有零Dirichlet边界条件的齐次热方程的解,该解对任意给定的$T\in(0,\infty)$不属于$L^2((0,T);H^2(\Omega)\cap H_0^1(\Omega))$。

英文摘要

Let $n\in \mathbb N\cap[2,\infty)$. In this article, we show that there exists a bounded $C^1$ domain $Ω\subset \mathbb R^n$ such that, for any given $s\in(1,2)\setminus\{\frac32\}$, \begin{align*} \left[H_0^1(Ω),H^2(Ω)\cap H_0^1(Ω)\right]_{s-1} =H^s(Ω)\cap H_0^1(Ω)=H_0^s(Ω) \end{align*} with equivalent norms, but \begin{align*} \left[H_0^1(Ω),H^2(Ω)\cap H_0^1(Ω)\right]_{\frac12} \subsetneqq H^{\frac32}(Ω)\cap H_0^1(Ω), \end{align*} which provides a counterexample to Problem 3.3.19 of Kenig in [CBMS Regional Conf. Ser. in Math. 83, 1994]. As applications, we prove that for such a domain $Ω$ \begin{align*} H^2(Ω)\cap H_0^1(Ω)\subsetneqq D(-Δ_D) \end{align*} (the domain of the Dirichlet Laplacian operator $-Δ_D$ on $Ω$) and construct a solution of the homogeneous heat equation with zero Dirichlet boundary condition, which does not belong to $L^2((0,T);H^2(Ω)\cap H_0^1(Ω))$ for any given $T\in(0,\infty)$.

2605.27118 2026-05-27 physics.ins-det cond-mat.mes-hall cond-mat.mtrl-sci cond-mat.soft cond-mat.stat-mech

A Levitated Random Telegraph Noise Spectrometer

悬浮随机电报噪声谱仪

Molly Message, Bianca C. J. Uy, Katie O'Flynn, Yugang Ren, Muddassar Rashid, Jonathan D. Pritchett, Qiongyuan Wu, Hyukjoon Kwon, Benjamin A. Stickler, James Millen

AI总结 利用悬浮微粒传感器探测随机电报噪声,通过共振行为放大位置涨落,实现六个时间尺度量级的噪声谱测量。

Comments 7 Figures, 19 pages (single-column), feel free to give comments!

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AI中文摘要

随机电报噪声是一种普遍存在于技术和自然界中的过程,其特征是在两个不同状态之间随机跳跃,等待时间服从泊松分布,并且是1/f噪声的起源。理解和表征这种噪声对于微米、纳米和量子技术的可靠运行至关重要。在这项工作中,我们使用悬浮微粒传感器探测随机电报噪声,该传感器的动力学几乎完全由这种非白噪声驱动。我们观察到一种惊人的共振行为,其特征是欠阻尼传感器的位置涨落增加了一千倍,从而能够测量六个时间尺度量级上的噪声谱特性。这项工作不仅提供了一种探测随机电报噪声的独特方法,还展示了一个在存在实际非白噪声的情况下研究非平衡随机动力学的平台,其应用范围从生物学到社会行为。

英文摘要

Random Telegraph Noise is a ubiquitous process manifesting across technology and the natural world. It is characterized by random jumps between two distinct states with Poissonian waiting times, and is the origin of 1/f noise. Understanding and characterizing this noise is critical for the reliable operation of micro-, nano- and quantum-technologies. In this work we probe random telegraph noise using a levitated microparticle sensor whose dynamics are driven almost entirely by this non-white source of noise. We observe a startling resonant behaviour, characterized by a thousand-fold increase in the underdamped sensor's position fluctuations, enabling us to measure the spectral properties of the noise over six decades of timescale. This work not only provides a unique way to probe random telegraph noise, but also demonstrates a platform for studying non-equilibrium stochastic dynamics in the presence of realistic non-white noise, with applications from biology to social behaviour.

2605.27111 2026-05-27 math.CO

The list r-hued coloring of trees and unicyclic graphs

树和单圈图的列表r-色调染色

Yu Miao, Fengxia Liu

AI总结 本文证明了树和大多数单圈图的列表r-色调色数等于min{r,Δ(G)}+1,并给出了例外情况的上界。

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AI中文摘要

设$r$为正整数,$G$为图。$G$的列表$r$-色调色数,记为$χ_{L,r}(G)$,是最小的整数$k$,使得对于$G$的每个$k$-列表$L$,$G$都有一个$(L,r)$-染色。文献[Discrete Math. 306 (16) (2006) 1997-2004]中证明了每棵树$G$满足$χ_{r}(G)=\min\{r,Δ(G)\}+1$。已知每个$n$阶圈图$C_{n}$有$χ_{L,r}(C_{n})=χ_{r}(C_{n})$。主要结果如下: (1) 若$G$是树,则$χ_{L,r}(G)=\min\{r,Δ(G)\}+1$; (2) 设$G$是不同构于圈$C_{n}$的单圈图。若$n\neq 5$且$r\geq3$,则$χ_{L,r}(G)=\min\{r,Δ(G)\}+1$;否则,$\min\{r,Δ(G)\}+1\leq χ_{L,r}(G)\leq \min\{r,Δ(G)\}+2$。

英文摘要

Let $r$ be a positive integer and $G$ be a graph. The list $r$-hued chromatic number of $G$, denoted by $χ_{L,r}(G)$, is the smallest integer $k$, such that for each $k$-list $L$ of $G$, $G$ has an $(L,r)$-coloring. It is proved in [Discrete Math. 306 (16) (2006) 1997-2004] that every tree $G$ satisfies $χ_{r}(G)=\min\{r,Δ(G)\}+1$. It is known that every cycle graph $C_{n}$ with order $n$ has $χ_{L,r}(C_{n})=χ_{r}(C_{n})$. The main results are the following: $(1)$ If $G$ is a tree, then $χ_{L,r}(G)=\min\{r,Δ(G)\}+1$; $(2)$ Let $G$ be a unicyclic graph which is not isomorphic to the cycle $C_{n}$. If $n\neq 5$ and $r\geq3$, then $χ_{L,r}(G)=\min\{r,Δ(G)\}+1$; otherwise, $\min\{r,Δ(G)\}+1\leqχ_{L,r}(G)\leq\min\{r,Δ(G)\}+2$.

2605.27109 2026-05-27 astro-ph.GA

Looking into the faintEst WIth MUSE (LEWIS): Exploring the nature of ultra-diffuse galaxies in the Hydra-I cluster. VI. A star-forming UDG in Hydra I: a rare UDG or a transition phase?

用MUSE观测最暗弱天体(LEWIS):探索长蛇I星系团中超弥散星系的本质。VI. 长蛇I中的一个恒星形成UDG:罕见的UDG还是过渡阶段?

Luca Rossi, Chiara Buttitta, Goran Doll, Enrichetta Iodice, Marco Gullieuszik, Marc Sarzi, Marco Mirabile, Johanna Hartke, Magda Arnaboldi, Rosa Calvi, Michele Cantiello, Enrico Maria Corsini, Giuseppe D'Ago, Jesús Falcón-Barroso, Francesca Fonzo, Duncan A. Forbes, Michael Hilker, Antonio La Marca, Alessandro Loni, Steffen Mieske, Maurizio Paolillo, Marina Rejkuba, Marilena Spavone, Chiara Spiniello

AI总结 利用MUSE积分场光谱数据,详细分析长蛇I星系团中唯一具有电离气体和发射线证据的恒星形成超弥散星系UDG 6,通过比较其性质与主要形成模型,揭示其可能起源于‘膨胀矮星系’并受环境过程影响。

Comments 13 pages, 10 figures

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AI中文摘要

本文作为ESO大型项目'用MUSE观测最暗弱天体(LEWIS)'的一部分,对一个富含气体的恒星形成超弥散星系(UDG)进行了详细分析。在LEWIS样本的UDG中,UDG 6是唯一拥有大量电离气体并存在发射线证据的星系,表明其近期有恒星形成活动。本研究的主要目标是通过比较该UDG的性质与这类极端星系的主要形成情景,来约束其形成历史。我们采用MUSE的积分场光谱学来推导UDG 6的恒星和气体组分的形态及结构性质。我们对MUSE数据立方体应用了光谱拟合和Voronoi镶嵌算法,以推导气体和恒星组分的运动学及性质。此外,通过多波段分光光度分析,我们推导了球状星团(GCs)群体的性质。我们确认UDG 6是长蛇I星系团的成员。它具有规则且拉长的形状,含有显著的尘埃含量、贫金属的电离气体组分以及一个古老的到中等年龄的恒星组分。通过发射线分析揭示了局部的、团块的恒星形成活动证据,并通过非锐化掩模分析发现了一个弧状的潮汐特征。UDG 6可能起源于一个'膨胀矮星系',其恒星含量被拉伸到更大半径,被动演化成一个更弥散的星系。由于位于星系团中一个动力学活跃的区域,具有潮汐特征和剥离现象,我们认为环境过程在塑造UDG 6的性质中发挥了作用。与邻近星系的潮汐相互作用可能触发了近期的恒星形成活动,而没有显著改变UDG 6中连贯的气体旋转。

英文摘要

This paper presents a detailed analysis of a gas-rich star-forming ultra-diffuse galaxy (UDG) as part of the ESO Large Programme 'Looking into the faintEst WIth MUSE (LEWIS)'. Among the UDGs in the LEWIS sample, UDG 6 is the only galaxy that hosts a significant amount of ionised gas with evidence of emission lines, suggesting recent star-forming activity. The main goal of this work is to constrain the formation history of this UDG by comparing its properties with the main formation scenarios proposed for this extreme class of galaxies. We adopted integral field spectroscopy from MUSE to derive the morphology and the structural properties of the stellar and gas components of UDG 6. We applied spectral fitting and Voronoi tessellation algorithms to the MUSE data-cube to derive the kinematics and properties of the gas and stellar component. Moreover, we derived the GCs populations' properties by applying a multi-band spectrophotometric analysis. We confirmed that UDG 6 is a member of Hydra I cluster. It is characterised by a regular and elongated shape and contains a significant dust content, a metal-poor ionised gas fraction and an underlying old-to-intermediate stellar component. Evidence of local and clumpy star-forming activity has been revealed through the analysis of emission line, and an arc-like tidal feature was discovered from unsharp masking analysis. UDG 6 might originate from a 'puffed-up dwarf' whose stellar content has been stretched out to larger radii, passively evolving into a more diffuse galaxy. Being located in a dynamically active region of the cluster, characterised by tidal features and stripping phenomena, we suggest that the environmental processes have played a role in shaping the properties of UDG 6. A tidal interaction with a nearby galaxy might have triggered recent star-formation activity, without dramatically altering the coherent gas rotation in UDG 6.

2605.27108 2026-05-27 physics.flu-dyn cond-mat.soft

Quantifying the liquid flow between a soap film and a vertical meniscus

量化肥皂膜与垂直弯月面之间的液体流动

Alexandre Vigna-Brummer, Simon Cox, Médéric Argentina, Christophe Brouzet, Christophe Raufaste

AI总结 通过实验、数值模拟和理论建模,研究了固体板插入垂直肥皂膜时引起的液体流入弯月面的通量,确定了通量系数并发现其在参数范围内保持恒定。

Comments 26 pages, 15 figures

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AI中文摘要

肥皂膜与其边界弯月面之间的液体交换控制着膜的排液和稳定性,直接影响表面气泡和液体泡沫的寿命。尽管最近取得了进展,但与边缘再生现象相关的这种耦合的定量表征仍不完整。单位接触长度的体积通量遵循一个成熟的标度律,涉及几何参数如膜高度和弯月面曲率半径。然而,由于膜-弯月面界面处复杂且间歇的流动,该关系的无量纲前因子——通量系数——对于垂直弯月面仍然难以确定。这里,我们量化了通过将固体板插入垂直肥皂膜而产生的进入弯月面的通量。我们考虑了垂直和倾斜板,并进一步研究了板倾斜度、高度和宽度的影响。聚焦于由膜供液驱动的弯月面生长动力学,我们分析了由毛细压力、重力和液体交换相互作用产生的稳态和瞬态过程。结合实验、数值模拟和理论建模,我们使用三种独立方法确定了通量系数,并表明它在所探索的参数范围内保持恒定。

英文摘要

Fluid exchange between a soap film and its bounding menisci governs film drainage and stability, with direct implications for the lifetime of surface bubbles and liquid foams. Despite recent advances, a quantitative characterization of this coupling, associated with the phenomenon of marginal regeneration, remains incomplete. The volumetric flux per unit length of contact follows a well-established scaling law involving geometrical parameters such as the film height and the meniscus radius of curvature. However, the dimensionless prefactor of this relation - the flux coefficient - remains difficult to determine for vertical menisci because of the complex and intermittent flows occurring at the film-meniscus interface. Here, we quantify this flux into the meniscus generated by inserting a solid plate into a vertical soap film. We consider both vertical and inclined plates and further investigate the effects of plate inclination, height, and width. Focusing on the dynamics of the growth of the meniscus driven by liquid supplied by the film, we analyze both steady and transient regimes resulting from the interplay between capillary pressure, gravity, and liquid exchange. Combining experiments, numerical simulations, and theoretical modelling, we determine the flux coefficient using three independent methods and show that it remains constant over the range of parameters explored.

2605.27106 2026-05-27 cs.DC cs.GT cs.MA cs.NI

Autonomic Federated-Market Orchestration for the Edge-Cloud Continuum

边缘-云连续体的自主联邦市场编排

Lauri Lovén, Roberto Morabito, Abhishek Kumar, Susanna Pirttikangas, Jukka Riekki, Sasu Tarkoma

AI总结 提出Neural Pub/Sub联邦代理自主基板,通过基于市场的价格信号实现去中心化编排,在边缘-云连续体中实现与集中式预言机相当的福利效率,并验证了其抗故障性和主权执行零开销。

Comments 35 pages, 5 figures (combined main paper + electronic supplement, folded into one document for arXiv)

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AI中文摘要

边缘-云计算连续体需要跨自治管理域扩展的自管理机制,同时尊重租户和运营商指定的数据主权。我们提出Neural Pub/Sub,一种联邦代理自主基板,其自组织行为源于基于市场的价格信号而非集中控制。其MAPE-K控制循环涵盖每个代理的健康和负载监控、边际成本清算价格分析、在多拟阵可行性区域上的放置规划、联邦跨域调度以及具有有界陈旧性价格信号的共享对等订阅摘要。计划步骤基于瓦尔拉斯收敛命题:在树和串并联服务依赖DAG上的总替代估值下,去中心化的基于价格的分配与集中式预言机的福利相匹配。我们在一个4-VM、4域、48工作节点的联邦边缘-云测试平台(单个数据中心,50 ms模拟广域网)上进行了1005次运行评估,并辅以公平进程计数分片预言机比较器。联邦市场以45/45的每种子胜出(符号检验p~2.8e-14,Hodges-Lehmann中位数-39.6 ms)优于单进程预言机2-4%;在与四分片集中式编排器同等进程数下,所有九个(流水线、负载)单元格的差距保持在±1.5%以内。轮询完成率在到达率5/10/15 pps下从98.8%下降到22.4%再到3.3%,而市场保持完成率;优势分解为三个瓦尔拉斯属性(信息完整性、准入控制、价格发现)。联邦能够承受代理死亡和网络分区(75个单元格中完成率≥98.7%),并且在60个治理网格运行中,主权执行没有增加可测量的运行时开销。异构域压力测试和跨站点广域网部署仍是未来工作。

英文摘要

The edge-cloud computing continuum demands self-management mechanisms that scale across autonomous administrative domains while honouring tenant- and operator-specified data sovereignty. We present Neural Pub/Sub, a federated-broker autonomic substrate whose self-organising behaviour emerges from market-based price signals rather than centralised control. Its MAPE-K control loop closes over per-broker health and load monitoring, marginal-cost clearing-price analysis, placement planning over a polymatroidal feasibility region, federated cross-domain dispatch, and shared peer subscription summaries with bounded-staleness price signals. The Plan step is anchored in a Walrasian convergence proposition: under gross-substitutes valuations on tree and series-parallel service-dependency DAGs, decentralised price-based allocation matches the welfare of a centralised oracle. We evaluate the substrate on a 4-VM, 4-domain, 48-worker federated edge-cloud testbed (single data centre, 50 ms emulated WAN) in a 1005-run campaign augmented by a fair-process-count sharded-oracle comparator. The federated market dominates a single-process oracle by 2-4% with 45 of 45 per-seed wins (sign-test p ~ 2.8e-14, Hodges-Lehmann median -39.6 ms); against a four-shard centralised orchestrator at equal process count the gap stays within +/-1.5% across all nine (pipeline, load) cells. Round-robin completion rate collapses 98.8% -> 22.4% -> 3.3% across arrival rates 5/10/15 pps while the market preserves completion; the advantage decomposes into three Walrasian properties (information completeness, admission control, price discovery). Federation withstands broker death and network partition (completion rate >= 98.7% across 75 cells), and sovereignty enforcement adds no measurable runtime overhead across 60 governance-grid runs. Heterogeneous-domain stressors and cross-site WAN deployment remain future work.

2605.27104 2026-05-27 cond-mat.mtrl-sci

Origin of the Temperature-Induced Gap Bowing of Formamidinium-Methylammonium Lead Iodide Perovskites: Role of Cationic Rattlers

温度诱导的甲脒-甲基铵铅碘钙钛矿带隙弯曲的起源:阳离子摆动子的作用

Kai Xu, Adrián Francisco-López, Bethan L. Charles, M. Isabel Alonso, Miquel Garriga, Mark T. Weller, Alejandro R. Goñi

AI总结 通过温度和压力依赖的光致发光测量,结合热膨胀和电子-声子相互作用,揭示了FA-MA混合阳离子铅碘钙钛矿低温相中温度诱导带隙弯曲的机制,其中电子-声子耦合由无机笼振动和FA摆动模式混合驱动。

Comments Manuscript 22 pages, 1 table and 4 figures plus 48 pages Supporting Information

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AI中文摘要

对半导体带隙温度依赖性的透彻理解对于优化光电器件至关重要。在这方面,在甲脒-甲基铵(FA-MA)铅碘钙钛矿低温相中观察到的显著温度诱导带隙弯曲的起源至今仍不明确。通过在一系列FA$_x$MA$_{1-x}$PbI$_3$混合阳离子单晶($x\in[0,1]$)上进行温度和压力依赖的光致发光测量,我们揭示了这种弯曲的起源。热膨胀和电子-声子相互作用效应都起作用。然而,后者是主导项,由与混合振动模式相关的异常电子-声子耦合机制的激活驱动,这些模式将涉及八面体倾斜的无机笼声子与低频FA摆动(即FA摆动子模式)相结合。这发生在正交和(伪)四方低温相中,对于FA浓度在20%至90%之间,可能具有交替八面体倾斜轴图案的条纹域。通过这种方式,我们揭示了铅卤钙钛矿的一种直接影响其光电特性的有趣行为。

英文摘要

A thorough understanding of the temperature dependence of semiconductor band gaps is essential for optimizing optoelectronic devices. In this respect, the origin of the pronounced temperature-induced gap bowing observed in low-temperature phases of formamidinium-methylammonium (FA-MA) lead iodide perovskites has remained elusive until now. By combining temperature and pressure-dependent photoluminescence measurements on a series of FA$_x$MA$_{1-x}$PbI$_3$ mixed-cation single crystals with $x\in[0,1]$, we unravel the origin of this bowing. Both thermal expansion as well as electron-phonon interaction effects are responsible. However, the latter is the leading term, driven by the activation of an anomalous electron-phonon coupling mechanism linked to mixed vibrational modes, which combine inorganic-cage phonons involving octahedral tilting with low-frequency FA librations, i.e., FA rattler modes. This occurs in the orthorhombic and (pseudo)tetragonal low-temperature phases, presumably featuring stripe domains with alternating octahedral tilt-axis patterns for FA concentrations between 20\% and 90\%. In this way, we have shed light on an intriguing behavior of lead halide perovskites that directly affects their optoelectronic properties.

2605.27103 2026-05-27 cs.IR

MuChator: Enabling Active Music Discovery via Conversational Music LLMs in Douyin Music

MuChator: 通过对话式音乐大语言模型在抖音音乐中实现主动音乐发现

Jiahao Liang, Linzhi Huang, Xuannan Liu, Xukai Wang, Xuanpu Luo, Yongchun Zhu, Jingwu Chen, Feng Zhang, Xiao Yang

AI总结 提出MuChator框架,通过音乐知识预训练、上下文感知指令微调和偏好对齐,使大语言模型能够理解用户用自然语言表达的情境化音乐意图,并在抖音音乐中实现主动音乐发现。

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AI中文摘要

抖音音乐是一个拥有数百万日活用户的大型平台,采用沉浸式、基于推送的发现范式,用户通过连续推荐被动探索音乐。虽然这种范式对被动音乐发现有效,但它将用户限制在推荐结果中,对明确指定收听意图的支持有限。与用户通过明确查询(如特定歌曲或艺术家)表达明确意图的传统搜索不同,现实中的主动音乐发现通常是情境化和口语化的,涉及模糊或未明确指定的请求。虽然大语言模型(LLM)支持自然语言交互,但它们在音乐发现中的直接使用仍受限于音乐领域知识不足、缺乏音乐查询协同推理以及对个性化偏好的浅层理解。为了解决这些挑战,我们引入了MuChator,一个基于交互式MusicLLM的框架,使用户能够用自然语言主动表达情境化音乐意图。MuChator包含三个关键组件:(1)音乐知识预训练,一个三阶段方案,逐步向LLM注入客观音乐知识、主观音乐知识和个性化音乐偏好;(2)上下文感知指令微调,通过自动化合成流水线构建高质量的用户-查询-音乐三元组,使LLM与主动和情境化的用户意图对齐;(3)基于混合奖励模型的偏好对齐,联合建模意图相关性、个性化偏好和基本约束,并使用基于GRPO的强化学习进行优化。在工业音乐推荐数据集上的广泛评估表明,MuChator优于领先的专有模型,如Gemini-3-Pro。该模型已在字节跳动旗下的抖音音乐App中部署,在线A/B测试中用户活跃天数提升了46.49%。

英文摘要

Douyin Music, a large-scale platform with millions of daily users, adopts an immersive, feed-based discovery paradigm, where users passively explore music through continuous recommendations. While effective for passive music discovery, this paradigm restricts users to recommendation results and provides limited support for explicitly specifying listening intents. Unlike conventional search, where users express well-defined intents through explicit queries such as specific songs or artists, real-world active music discovery is often situational and colloquial, involving vague or underspecified requests. While LLMs enable natural language interaction, their direct use in music discovery remains limited by insufficient music-domain knowledge, lack of music-query collaborative reasoning, and shallow understanding of personalized preferences. To address these challenges, we introduce MuChator, an interactive MusicLLM-based framework that enables users to actively express situational music intents in natural language. MuChator incorporates three key components: (1) Music Knowledge Pre-training, a three-stage scheme that incrementally injects objective music knowledge, subjective music knowledge, and personalized music preferences into LLMs; (2) Context-aware Instruction Tuning, which constructs high-quality user-query-music triplets through an automated synthesis pipeline to align LLMs with active and situational user intents; and (3) Preference Alignment with Hybrid RM, which jointly models intent relevance, personalized preferences, and basic constraints, and is optimized using GRPO-based reinforcement learning. Extensive evaluations on industrial music recommendation datasets demonstrate that MuChator outperforms leading proprietary models, such as Gemini-3-Pro. The model has been deployed on Douyin Music App within ByteDance, with 46.49\% improvement of user active days in online A/B test.

2605.27100 2026-05-27 q-bio.PE

Logistic dynamics of small populations with demographic stochasticity

具有人口统计学随机性的小种群逻辑斯蒂动力学

Lucas M. Brugevin, Damián H. Zanette

AI总结 本研究通过随机出生、死亡和移民事件建模有限种群,利用解析和数值方法刻画活跃期和空缺期的统计特性,发现活跃期呈现双峰分布,并探讨了网络结构对种群聚类和空缺期频率的影响。

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Journal ref
Phys. Rev. E 113 (2026) 054315
AI中文摘要

我们研究了一个受生态学启发的有界种群模型,其动力学由随机出生、死亡和移民事件支配。个体数量的随机波动导致活跃期和空缺期交替出现,其中种群分别存在和灭绝。利用解析和数值技术,我们刻画了这两种时期的统计特性,量化了它们的持续时间和频率,以及活跃期中的典型种群规模。与由逻辑斯蒂动力学支配的确定性平均场行为形成鲜明对比的是,活跃期可能表现出明显的双峰性:要么持续时间短且种群规模非常小,要么持续时间长且种群规模接近最大值。我们还研究了当种群在三种随机网络(Erdős-Rényi、正则和地理网络)上演化时这些结果如何变化。网络结构的主要作用是诱导种群聚类,个体聚集为局部群体,这反过来限制了种群增长并增加了空缺期的频率。

英文摘要

We study an ecology-inspired model for a population of bounded size, whose dynamics is governed by random birth, death, and immigration events. Stochastic fluctuations in the number of individuals give rise to a succession of alternating active and vacant periods, where the population is respectively extant and extinct. Using both analytical and numerical techniques, we characterize the statistics of the two kinds of period, quantifying their duration and frequency, and the typical population sizes in active periods. In sharp contrast to the deterministic mean-field behavior, governed by logistic dynamics, active periods may exhibit pronounced bimodality: either short durations with very small populations, or much longer durations with population sizes close to the maximum. We also investigate how these results change when the population evolves on random networks of three classes: Erdős-Rényi, regular, and geographic. The main effect of the network structure is to induce population clustering, with individuals aggregated into localized groups. This, in turn, limits population growth and increases the frequency of vacant periods.

2605.27099 2026-05-27 cond-mat.other physics.app-ph

Antisymmetric spontaneous resistivity anisotropy due to hard-axis collapse in polycrystalline Co thin films

多晶Co薄膜中由于硬轴坍塌引起的反对称自发电阻率各向异性

Y. Fernandes, J. Geshev, A. M. H. de Andrade, A. D. C. Viegas

AI总结 研究多晶Co薄膜中与磁化硬轴坍塌相关的磁电阻现象,发现平面霍尔电阻在室温下呈现多个稳定且可复现的剩余态,可用于信息存储,并提出基于剩余平面霍尔效应的自旋电子存储和传感平台。

Comments 5 pages, 4 figures

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AI中文摘要

我们研究了与多晶Co薄膜中磁化硬轴坍塌相关的磁电阻现象。输运测量表明,对于外加磁场的特定取向,系统在面内纵向和横向电压响应中表现出不同的剩余电阻水平。特别地,平面霍尔电阻在室温下显示出多个稳定且可复现的水平,从而能够识别至少三个可区分并用于信息存储的剩余态。这些电阻水平源于在外加磁场在硬轴区域施加和移除后稳定的非均匀磁构型。由于这一现象在很大程度上尚未被探索,我们提出了一项初步研究,从应用物理的角度探讨其潜在影响。在Si衬底上生长的多晶Co薄膜中观察到的这种行为,为基于剩余平面霍尔效应的自旋电子存储和传感器件提供了一种简单且低成本的平台。

英文摘要

We investigate magnetoresistance phenomena associated with the magnetization hard-axis collapse in polycrystalline Co thin films. Transport measurements reveal that, for specific orientations of the applied magnetic field, the system exhibits distinct remanent resistance levels in both the in-plane longitudinal and transverse voltage responses. In particular, the planar Hall resistance shows multiple stable and reproducible levels at room temperature, enabling the identification of at least three remanent states that can be distinguished and used for information storage. These resistance levels originate from non-uniform magnetic configurations stabilized after the application and removal of the external magnetic field in the hard-axis region. Since this phenomenon remains largely unexplored, we present an incipient study addressing its potential implications from an applied-physics perspective. The observation of such behavior in polycrystalline Co thin films grown on Si substrates suggests a simple and low-cost platform for spintronic memory and sensing devices based on the remanent planar Hall effect.

2605.27098 2026-05-27 cs.GT cs.DS

Improved Hardness Results for Nash Social Welfare, Budgeted Allocation and GAP via the Unique Games Conjecture

通过唯一游戏猜想改进纳什社会福利、预算分配和GAP的硬度结果

Vignesh Viswanathan

AI总结 本文通过唯一游戏猜想,针对不可分割商品分配问题,改进了纳什社会福利、预算分配和广义分配问题的近似硬度下界。

Comments To Appear at EC 2026

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AI中文摘要

我们考虑将一组不可分割商品分配给具有可加估值的智能体的问题。在计算机科学和运筹学文献中,该问题已在各种目标下得到研究。我们的主要贡献是使用该问题设计了一个新的独裁者测试,该测试可以将独裁者与任何远离独裁者的函数区分开。我们使用这个测试来证明以下硬度结果(假设唯一游戏猜想为真):(1) 我们证明,近似最大纳什社会福利的因子优于 $\sqrt[3]{ rac{81}{65}} - \varepsilon \approx 1.0761$ 是 NP-难的。这改进了之前已知的最佳不可近似因子 $\sqrt{ rac87} - \varepsilon \approx 1.069$。(2) 我们证明,近似最大预算分配的因子优于 $ rac{243}{227} - \varepsilon \approx 1.07$ 是 NP-难的。这改进了之前已知的最佳不可近似因子 $ rac{16}{15} - \varepsilon \approx 1.067$。(3) 我们证明,近似最大广义分配问题(GAP)的因子优于 $ rac{145}{129} - \varepsilon \approx 1.124$ 是 NP-难的。这改进了之前已知的最佳不可近似因子 $ rac{11}{10} - \varepsilon \approx 1.10$。

英文摘要

We consider the problem of dividing a set of indivisible goods among agents with additive valuations. This problem has been studied under various objectives in both the computer science and the operations research literature. Our main contribution is a novel dictator test using this problem, which can separate a dictator from any function sufficiently far from a dictator. We use this test to prove the following hardness results (assuming the unique games conjecture is true): (1) We show that it is NP-hard to approximate the max Nash welfare by a factor better than $\sqrt[3]{\frac{81}{65}} - \varepsilon \approx 1.0761$. This improves on the previous best known inapproximability factor of $\sqrt{\frac87} - \varepsilon \approx 1.069$. (2) We show that it is NP-hard to approximate the maximum budgeted allocation by a factor better than $\frac{243}{227} - \varepsilon \approx 1.07$. This improves on the previous best known inapproximability factor of $\frac{16}{15} - \varepsilon \approx 1.067$. (3) We show that it is NP-hard to approximate the max generalized assignment problem (GAP) by a factor better than $\frac{145}{129} - \varepsilon \approx 1.124$. This improves on the previous best known inapproximability factor of $\frac{11}{10} - \varepsilon \approx 1.10$.

2605.27096 2026-05-27 astro-ph.SR

Observations of stable pickup He$^+$ tori in a magnetic flux rope at 0.85 au

在0.85 au处磁通量绳中稳定捕获的He$^+$环状速度分布观测

Chaoran Gu, Lars Berger, Verena Heidrich-Meisner, Erik Jentsch, Robert F. Wimmer-Schweingruber, Lars Seimetz

AI总结 利用Solar Orbiter卫星数据,在0.85 au处的磁通量绳中观测到稳定的拾起He$^+$环状速度分布,持续超过10小时而无显著散射,表明这些环由过去注入同一太阳风流的大量拾起离子构成。

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AI中文摘要

星际拾起离子起源于中性星际介质,在日光层中被电离,并被太阳风捕获。它们最初形成环状速度分布函数,通常认为通过俯仰角散射迅速转变为各向同性壳层分布。利用Solar Orbiter上的超热电子质子探测器,我们以前所未有的1分钟分辨率观测到清晰的环状速度分布函数。虽然这些环在1分钟时间尺度上变化,但它们保持稳定超过10小时,没有显著散射迹象。我们得出结论,这些环由过去注入同一太阳风流中的预期总拾起离子数的巨大比例构成。

英文摘要

Interstellar pickup ions originate from the neutral interstellar medium, are ionized in the heliosphere, and picked up by the solar wind. They initially form a torus-shaped velocity distribution function, which is generally believed to be transformed rapidly into an isotropic shell distribution by pitch-angle scattering. With the SupraThermal Electron Proton onboard Solar Orbiter we observe clear torus-shaped velocity distribution functions at an unprecedented one minute resolution. While these tori are variable on a time scale of one minute, they remain stable for over ten hours without signs of significant scattering. We conclude that they are populated by a huge fraction of the expected total number of pick-up ions injected in the past of the same solar wind stream.

2605.27094 2026-05-27 eess.SY cs.SY

En-route Charging Coordination for Electric Trucks

电动卡车途中充电协调

Joas Kahlert, Ruiting Wang, Jonas Mårtensson

AI总结 针对长途货运电动化中充电基础设施容量有限和拥堵问题,提出一种基于混合整数规划的协调充电调度框架,可降低充电、运营、电池退化和拥堵延迟成本,相比非协调调度节省高达36%的成本。

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AI中文摘要

长途货运的电气化带来了若干新挑战,例如途中充电基础设施容量有限和拥堵。为减少高峰时段的等待时间,本文提出了一种协调充电调度框架。该方法采用混合整数规划,优化充电、运营、电池退化和拥堵延迟相关的充电成本,并考虑一系列场景。结果表明,与非协调调度相比,协调调度可节省高达36%的成本,特别是通过减少电池退化和延迟成本。

英文摘要

The electrification of long-haul freight transport introduces several new challenges, such as the limited capacity and congestion at en-route charging infrastructure. To reduce waiting times during peak periods, this paper proposes a framework for coordinated charging scheduling. The approach employs a mixed-integer formulation to optimize charging-related costs across charging, operation, battery degradation, and congestion delay, considering a range of scenarios. The results demonstrate that coordinated scheduling yields substantial cost savings up to 36% compared to uncoordinated scheduling, particularly by reducing battery degradation and delay costs.

2605.27092 2026-05-27 math.QA

Duplicial sets, crossed $G$-sets and descent categories

Duplicial 集、交叉 $G$-集与下降范畴

John Boiquaye, Ralph Twum

AI总结 本文通过左 $\chi$-余代数的一般理论,展示了用于构造循环集的循环算子的一个系数上的附加结构是这一理论的实例,并指出一般情况下另一系数需配备交叉 $G$-集结构。

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AI中文摘要

本注记的目的是表明左 $\chi$-余代数(它是用于构造循环集的循环算子的系数之一上的附加结构,该循环集推广了 Loday 关于群的扭曲神经)是左 $\chi$-余代数一般理论的一个实例。还表明,在一般情况下,得到的循环算子要求另一个系数需要配备一个交叉 $G$-集结构。

英文摘要

The goal of this note is to show that the left $χ$-coalgebra, which is an additional structure on one of the coefficients used in the construction of the cyclic operator for the cyclic sets that generalises the twisted nerve of a group by Loday is an instance of a general theory of left $χ$-coalgebras. It is also shown that in the general case, the resulting cyclic operator requires that the other coefficient needs to be equipped with a crossed $G$-sets structure.

2605.27089 2026-05-27 physics.plasm-ph

ITER ECE front-end design, alignment and in-situ calibration

ITER ECE 前端设计、对准与原位校准

Saeid Houshmandyar, W. L. Rowan, J. P. Ziegel, A. Ouroua

AI总结 本文介绍了ITER电子回旋辐射诊断的前端准光学系统设计,采用场阑概念约束高斯光束,并通过原位热校准源实现独立绝对电子温度测量,同时分析了前端与偏振分束器对准误差对空间分辨率的影响。

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AI中文摘要

ITER的电子回旋辐射(ECE)诊断套件采用前端准光学(QO)系统,其设计从根本上受到场阑概念的约束。场阑定义了高斯光束在整个光学系统及等离子体内的变化,从而设定了ECE采样体积和空间分辨率。利用高斯光束传输标准优化的原位热校准源,提供了独立且绝对的电子温度测量。QO系统从前端延伸至包括偏振分束器单元(PSU)、传输线和开关站,形成通往ECE仪器的集成光路。前端与PSU之间的对准误差会减小有效场阑尺寸,降低空间分辨率和测量保真度。斜向ECE视图是ITER设计的关键特征,增强了对非热电子群体的敏感性,并补充了新经典撕裂模的诊断。集成QO设计和等离子体物理理解对于可靠的ITER ECE测量至关重要。

英文摘要

The electron cyclotron emission (ECE) diagnostics suite at ITER utilizes a front-end quasi-optical (QO) system whose design is fundamentally constrained by a field-stop concept. The field-stop defines the Gaussian beam variation throughout the optical system and within the plasma, thereby setting the ECE sampling volume and spatial resolution. An in-situ hot calibration source, optimized using Gaussian beam transmission criteria, provides independent and absolute electron temperature measurements. The QO system extends beyond the front-end to include the polarization splitter unit (PSU), transmission lines, and switchyard, forming an integrated optical path to the ECE instruments. Misalignment between the front-end and PSU reduces the effective field-stop size, degrading spatial resolution and measurement fidelity. The oblique ECE view, a key feature of the ITER design, enhances sensitivity to non-thermal electron populations and complements the diagnosis of neoclassical tearing modes. Integrated QO design and plasma physics understanding are essential for reliable ITER ECE measurements.

2605.27086 2026-05-27 math.DG math.AP

The Wasserstein--Ebin Metric: A Geometric Lift of Unbalanced Optimal Transport to the space of Riemannian metrics

Wasserstein--Ebin 度量:不平衡最优输运到黎曼度量空间的几何提升

Martin Bauer, Peter W. Michor, François-Xavier Vialard

AI总结 本文通过动态和静态形式化方法,将不平衡最优输运从正密度空间扩展到黎曼度量空间,引入 Wasserstein--Ebin 度量,并证明体积映射定义了到 Wasserstein--Fisher--Rao 度量的黎曼淹没。

Comments 31 pages

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AI中文摘要

我们引入了动态和静态形式化方法,将不平衡最优输运从正密度空间正式扩展到黎曼度量空间。第一个构造基于动态变分形式,其中黎曼度量的演化由输运和源项驱动。选择 $L^2$-度量惩罚输运向量场,Ebin 度量惩罚源分量,在黎曼度量流形上产生一个新的黎曼度量,我们称之为 Wasserstein--Ebin 度量。我们的主要结果表明,体积映射定义了从 Wasserstein--Ebin 度量到光滑密度空间上的 Wasserstein--Fisher--Rao 度量的黎曼淹没。此外,我们构造了一个从切丛的自同构群到黎曼度量空间的黎曼淹没,将 Otto 对 Wasserstein 度量的几何描述推广到 Wasserstein--Ebin 度量的设置。为了提出不平衡最优黎曼度量输运的静态形式,我们在黎曼度量空间上引入了两种 Kullback--Leibler 型散度:一种受矩阵信息几何启发,另一种通过体积映射与密度上的经典 Kullback--Leibler 散度相关。建立静态和动态形式之间的联系仍是未来工作的一个开放方向。

英文摘要

We introduce dynamic and static formulations that formally extend unbalanced optimal transport from the space of positive densities to the space of Riemannian metrics. The first construction is based on a dynamic variational formulation in which the evolution of a Riemannian metric is driven by transport together with a source term. Choosing the $L^2$-metric to penalize the transport vector field and the Ebin metric to penalize the source component yields a new Riemannian metric on the manifold of Riemannian metrics, which we call the Wasserstein--Ebin metric. Our main result shows that the volume map defines a Riemannian submersion from the Wasserstein--Ebin metric to the Wasserstein--Fisher--Rao metric on the space of smooth densities. In addition, we construct a Riemannian submersion from the automorphism group of the tangent bundle onto the space of Riemannian metrics, providing a generalization of Otto's geometric description for the Wasserstein metric to the setting of the Wasserstein--Ebin metric. To propose a static formulation of unbalanced optimal Riemannian metric transport, we introduce two Kullback--Leibler-type divergences on the space of Riemannian metrics: one inspired by matrix information geometry, and another related, through the volume map, to the classical Kullback--Leibler divergence on densities. Establishing a link between the static and dynamic formulations remains an open direction for future work.

2605.27085 2026-05-27 stat.ME math.ST stat.AP stat.TH

Estimation and Inference for Win Measures with Multiple Ordinal Endpoints Subject to Missingness

具有缺失数据的多个有序终点胜率指标的估计与推断

Yi Liu, Huiman Barnhart, Sean O'Brien, Yuliya Lokhnygina, Roland A. Matsouaka

AI总结 针对多个层次有序终点存在缺失数据的情况,提出逆概率加权(IPW)和增强逆概率加权(AIPW)估计量,以纠正标准成对比较方法的偏差,并实现双重稳健性。

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AI中文摘要

胜率指标,包括胜率(WR)、胜算(WO)、净收益(NB)和结局排序期望(DOOR),越来越多地用于具有多个层次有序终点的随机临床试验中。然而,在实践中,一个或多个组分终点可能存在缺失数据。标准的成对比较方法将缺失结局的对视为平局,即使数据是完全随机缺失(MCAR),也可能产生有偏估计。尽管针对删失生存终点已开发了逆删失概率加权(IPCW)方法,但针对缺失层次有序终点的相应方法尚不可用。为填补这一空白,我们针对具有缺失数据的层次有序终点,开发了逆概率加权(IPW)和增强逆概率加权(AIPW)估计量,允许缺失依赖于治疗分配和基线协变量。IPW估计量通过使用定义胜率指标的联合单元格概率估计中涉及的联合非缺失概率对完整观测结局进行重新加权,从而纠正偏差。AIPW估计量额外纳入结局建模,提高了效率并实现了双重稳健性。在推断方面,我们基于影响函数推导了两种方法的闭式方差估计量。模拟研究表明,标准方法可能存在显著偏差,而所提出的IPW和AIPW估计量保持一致,且覆盖概率接近名义水平。此外,AIPW估计量通常比IPW估计量更有效。在SCOUT-CAP和ACTT-1试验中的应用说明了所提出方法的实用性。提供了R包WinMO以供实现。

英文摘要

Win measures, including the win ratio (WR), win odds (WO), net benefit (NB), and desirability of outcome ranking (DOOR), are increasingly used in randomized clinical trials with multiple hierarchical ordinal endpoints. In practice, however, one or more component endpoints may have missing data. The standard pairwise-comparison approach, which treats pairs with missing outcomes as ties, can produce biased estimates, even if the data are missing completely at random (MCAR). Although inverse probability of censoring weighting (IPCW) methods have been developed for censored survival endpoints, corresponding methods for addressing missing hierarchical ordinal endpoints are not yet available. To address this gap, we develop inverse probability weighting (IPW) and augmented IPW (AIPW) estimators for win measures with hierarchical ordinal endpoints subject to missing data, allowing missingness to depend on treatment assignment and baseline covariates. The IPW estimator corrects bias by reweighting complete observed outcomes using joint non-missingness probabilities involved in estimating the joint cell probabilities that define the win measures. The AIPW estimator additionally incorporates outcome modeling, improving efficiency and achieving double robustness. For inference, we derive closed-form variance estimators for both methods based on influence functions. Simulation studies show that the standard approach can be substantially biased, whereas the proposed IPW and AIPW estimators remain consistent with near-nominal coverage. Furthermore, the AIPW estimator is generally more efficient than IPW estimator. Applications to the SCOUT-CAP and ACTT-1 trials illustrate the practical utility of the proposed methods. An R package, WinMO, is provided for implementation.

2605.27084 2026-05-27 astro-ph.EP

Destructuring the disk of AB Aurigae: Dynamics and accretion

AB Aurigae 盘的结构分解:动力学与吸积

Anthony Boccaletti, Emmanuel Di Folco, Anne Dutrey, Tang Ya-Wen, Stephane Guilloteau, Thomas Collin-Dufresne, Anne-Marie Lagrange, Eric Pantin, Jeffrey S. Bary, Nuria Huélamo, József Varga, Julien Milli, Tracy Beck, Vincent Piétu, William Danchi, Bin Ren, Clément Baruteau, Mickael Bonnefoy, Maud Langlois, Sylvestre Lacour, Bruno Lopez, Alexis Matter, Julien Woillez, Florentin Millour, Matthis Houllé, Philippe Berio

AI总结 利用近红外偏振和Hα成像数据,分析AB Aur盘的整体动力学和结构,发现亚开普勒旋转,并约束致密源和候选行星的轨道及吸积率。

Comments 21 pages, to appear in Astronomy & Astrophysics

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AI中文摘要

在本文中,我们展示了AB Aur盘在三个历元(跨度3.85年)的SPHERE/IRDIS近红外偏振图像,以及单个历元的SPHERE/ZIMPOL Hα图像。本研究的目的是分析整个盘及各种结构在近红外偏振测量中的动力学,并识别Hα发射源以推导其质量吸积率的约束。近红外动力学研究表明,盘整体遵循开普勒旋转,但在半径小于约60 au处观察到偏离行为。在最小半径约25 au处,我们测量到3.85年内偏离开普勒旋转高达约12度,表明亚开普勒旋转。毫米波腔内的两条明亮螺旋具有不同的动力学趋势,我们讨论了它们与已识别候选行星的可能联系。我们还讨论了非开普勒行为的含义,并认为这可能与多个原行星在盘平面外椭圆轨道上运行的相互作用有关。此外,对致密源(标记为f1、f2和f3)的轨道分析表明,它们的轨道平面相对于盘平面倾斜显著,达几十度。阴影的变化表明它们是由位于约60 au内的光学厚区域产生的。对于Hα光度分析,我们得出整个特征f1的通量约为8.22×10^{-15} erg/s/cm^2,但在AB Aur b位置仅为6.46×10^{-16} erg/s/cm^2,与未探测结果一致。如果f1是一个点源且吸积在1 Myr内保持恒定,根据磁层吸积模型,它对应于约5-20个木星质量,或根据边界层吸积模型对应于约6-10个木星质量。

英文摘要

In this paper, we present near-IR polarized images of the AB Aur disk at three epochs spanning 3.85 years with SPHERE/IRDIS, as well as Halpha images obtained with SPHERE/ZIMPOL at a single epoch. The purpose of this study is to analyze the dynamics of the entire disk and of the various structures in near-IR polarimetry, and to identify sources of Halpha emission to derive constraints on their mass accretion rate. The dynamical study in the near-IR shows that the disk globally follows Keplerian rotation, but we observe a departure from this behavior at radii smaller than ~60au. At the smallest radius of ~25au, we measure a deviation from Keplerian rotation as large as ~12deg over 3.85 years, demonstrating sub-Keplerian rotation. The two bright spirals within the millimeter cavity have different dynamic trends, and we discuss their possible link with the identified planet candidates. We also discuss the implications of the non-Keplerian behavior, and we posit that it could be related to interactions with multiple protoplanets orbiting out of the disk plane on elliptical orbits. Furthermore, the orbital analysis of the compact sources (labeled f1, f2, and f3) suggests that their orbital planes are significantly inclined with respect to the disk plane by several tens of degrees. The variability of the shadows suggests that they are produced by optically thick regions located within ~60au. For the photometric analysis in Halpha, we derive a flux of about 8.22x10^{-15} erg/s/cm^2 for the entire feature f1, but only 6.46x10^{-16} erg/s/cm^2 at the location of AB Aur b, consistent with non-detection. If f1 were a point source and the accretion remained constant for 1Myr, it would correspond to ~5-20 Jupiter masses according to the magnetospheric accretion model or ~6-10 Jupiter masses according to the boundary layer accretion model.

2605.27077 2026-05-27 cond-mat.mtrl-sci

Electron Polaron at Neutral 180$^\circ$ Domain Wall in PbTiO$_3$: Stability, Trapping Energies, and Transverse Polarization

PbTiO3中中性180°畴壁处的电子极化子:稳定性、俘获能量和横向极化

Mohammad Amirabbasi, Jochen Rohrer, Karsten Albe

AI总结 使用Hubbard修正的密度泛函理论研究四方相PbTiO3中中性PbO中心180°畴壁处Ti中心电子极化子的稳定性、俘获能量和横向极化响应。

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AI中文摘要

我们使用Hubbard修正的密度泛函理论研究四方相PbTiO3中中性PbO中心180°畴壁处Ti中心的电子极化子。通过有限尺寸校正的极化子能级对齐方法确定Ti 3d态的Hubbard参数,在体PbTiO3中形成稳定的电子极化子,俘获能量为-0.06 eV。在畴壁超胞中,过剩电子局域在Ti上,形成具有占据的d_{xy}轨道带隙态的Ti^{3+}中心。比较类体Ti位和近壁Ti位发现,它们的俘获能量仅相差约0.01 eV,表明该中性畴壁不提供显著的电子极化子偏析热力学驱动力。虽然面外极化的Ising型反转得以保持,但局域电子在垂直于畴壁的方向上诱导出有限的横向极化分量,增强了局部的Néel型畸变,当极化子位于畴壁时这种畸变最强。这些结果表明,PbTiO3中的中性180°畴壁不会显著改变Ti中心电子极化子的稳定性,但可以通过局域横向极化响应与极化子诱导的晶格畸变耦合。

英文摘要

We use density-functional theory with a Hubbard correction to investigate Ti-centered electron polarons at neutral PbO-centered $180^\circ$ domain walls in tetragonal PbTiO$_{3}$. The Hubbard parameter for Ti $3d$ states is determined using the finite-size-corrected polaronic energy-level alignment procedure, yielding stable electron-polaron formation in bulk PbTiO$_3$ with a trapping energy of $-$0.06 eV. In the domain-wall supercell, the excess electron localizes on Ti and forms a Ti$^{3+}$ center with an occupied $d_{xy}$ orbital in-gap state. Comparison of bulk-like and near-wall Ti sites shows that their trapping energies differ by only about 0.01 eV, indicating that this neutral domain wall does not provide a significant thermodynamic driving force for electron-polaron segregation. While the Ising-like reversal of the out-of-plane polarization is preserved, the localized electron induces a finite transverse polarization component normal to the wall, enhancing a local Néel-like distortion that is strongest when the polaron is located at the wall. These results show that neutral $180^\circ$ domain walls in PbTiO$_3$ do not substantially alter the stability of Ti-centered electron polarons, but they can couple to the polaron-induced lattice distortion through a localized transverse polarization response.