Physica A: Statistical Mechanics and its Applications最新文献

{"title":"Facilitating cooperative behavior through reinforcement learning with age-driven state transitions in structured populations","authors":"Ran Zhang ,&nbsp;Tianbo An ,&nbsp;Jian Zhao ,&nbsp;Zhen Wang","doi":"10.1016/j.physa.2026.131319","DOIUrl":"10.1016/j.physa.2026.131319","url":null,"abstract":"<div><div>The Q-learning algorithm in reinforcement learning closely parallels human experience based decision making, and has been widely applied to evolutionary game theory to study the emergence of cooperation. Previous studies have expanded the definition of the state space to some extent, but they have not captured the continuity of states in the temporal dimension. To address this gap, we propose a multistate transition mechanism driven by strategy age, where an agent’s state is defined by the time steps it persists with the same strategy. As the strategy age increases, the agent transitions into higher states until reaching the maximum threshold. For comparison, we also design a bistate mechanism that distinguishes states only between ages below and above the threshold. Simulation results show that both multistate and bistate mechanisms promote cooperation significantly better than memoryless and self-regarding Q-learning, with the multistate mechanism performing best. The key reason is that high age defectors see their Q-value of choosing defection drop below that of choosing cooperation and thus occasionally switch to cooperate under prolonged exposure to defectors. These switches periodically seed new low age cooperators, continually replenishing the cooperative pool. Raising the strategy age threshold expands the state space, giving defectors more chances to switch to cooperation and further boosting cooperation. By contrast, the bistate mechanism partitions the space too coarsely, limiting such transitions and yielding weaker outcomes. We also find that cooperation is most likely to emerge under moderate learning rates <span><math><mi>α</mi></math></span> and higher discount factors <span><math><mi>γ</mi></math></span>.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"686 ","pages":"Article 131319"},"PeriodicalIF":3.1,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146049116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fine structure of exciton: Schrödinger’s cat and superfluidity","authors":"Xuebing Gong","doi":"10.1016/j.physa.2026.131315","DOIUrl":"10.1016/j.physa.2026.131315","url":null,"abstract":"<div><div>Spin orbit coupling (SOC) of the exciton induces the exciton fine structure, which holding significant potential in nanotechnology and optoelectronics. This paper theoretically examines exciton fine structure driven by SOC. The two bright excitons, interacting with photons, support three bound states: upper polariton (UP), middle polariton (MP), and lower polariton (LP), leading to Rabi oscillations and Schrödinger cat states between MP and LP. Moreover, the Kosterlitz-Thouless (KT) transition temperature of polaritons is enhanced by two difference bright excitons interaction. And the interactions between bright and dark excitons further recombine the MP, LP, and dark states into three energy branches. These findings advance understanding in quantum foundations, many-body physics, and quantum information.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"686 ","pages":"Article 131315"},"PeriodicalIF":3.1,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum entanglement in quasi-one-dimensional spin systems with alternating interactions","authors":"Lizhen Hu ,&nbsp;Yuliang Xu ,&nbsp;Panpan Zhang ,&nbsp;Xiangmu Kong ,&nbsp;Shiwei Yan","doi":"10.1016/j.physa.2026.131316","DOIUrl":"10.1016/j.physa.2026.131316","url":null,"abstract":"<div><div>In this study, we systematically investigate bipartite quantum entanglement in quasi-one-dimensional Heisenberg systems, including alternating-interaction spin chains and ladders, using the density matrix renormalization group method. The pairwise entanglement quantified by concurrence is mainly investigated, and the effects of alternating interactions, frustrations and open boundary conditions (OBC) on them are discussed in detail. For Heisenberg chains, the introduction of second- and third-nearest-neighbor interactions induces a redistribution of entanglement. Notably, the ground state exhibits enhanced robustness in long-distance entanglement (LDE) compared to conventional single chains. In the spin ladder systems, LDE is suppressed when rung or diagonal chain couplings are introduced individually, but their coexistence enhances LDE, with an optimal ratio of rung to diagonal couplings of 1:1.3.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"686 ","pages":"Article 131316"},"PeriodicalIF":3.1,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Competing ferromagnetic and antiferromagnetic phases on the frustrated Ising honeycomb lattice","authors":"P.F. Dias ,&nbsp;F.M. Zimmer ,&nbsp;N.G. Fytas ,&nbsp;M. Schmidt","doi":"10.1016/j.physa.2026.131321","DOIUrl":"10.1016/j.physa.2026.131321","url":null,"abstract":"<div><div>We investigate the frustrated <span><math><msub><mrow><mi>J</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>–<span><math><msub><mrow><mi>J</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>–<span><math><msub><mrow><mi>J</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> Ising model on the honeycomb lattice, featuring first- and second-neighbor ferromagnetic couplings (<span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>&gt;</mo><mn>0</mn></mrow></math></span> and <span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>&gt;</mo><mn>0</mn></mrow></math></span>) and third-neighbor antiferromagnetic interactions (<span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>&lt;</mo><mn>0</mn></mrow></math></span>). Using the cluster mean-field method, we analyze the phase transitions in the regime <span><math><mrow><mn>1</mn><mo>/</mo><mn>2</mn><mo>&lt;</mo><msub><mrow><mi>J</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>/</mo><msub><mrow><mi>J</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>≤</mo><mn>1</mn></mrow></math></span>, where ferromagnetic and antiferromagnetic phases compete. Our results reveal that near the strongly frustrated limit <span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>/</mo><msub><mrow><mi>J</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><mo>−</mo><mn>1</mn></mrow></math></span>, the system exhibits order-by-disorder state selection, tricritical and bicritical behavior, critical endpoints, and two successive phase transitions. The ferromagnetic–paramagnetic transition remains second order across the entire interaction range, whereas the antiferromagnetic–paramagnetic boundary shows a richer behavior, including both first- and second-order transitions as well as tricriticality. Increasing the second-neighbor coupling <span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>/</mo><msub><mrow><mi>J</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></math></span> narrows the range of <span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>/</mo><msub><mrow><mi>J</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></math></span> where first-order antiferromagnetic–paramagnetic transitions occur; beyond a certain threshold, only second-order order–disorder transitions persist. Consequently, the tricritical point shifts toward <span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>/</mo><msub><mrow><mi>J</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>≈</mo><mo>−</mo><mn>1</mn></mrow></math></span> as <span><math><mrow><msub><mrow><mi>J</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>/</mo><msub><mrow><mi>J</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></math></span> increases, culminating in a bicritical point where the antiferromagnetic, ferromagnetic, and paramagnetic phases meet.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"686 ","pages":"Article 131321"},"PeriodicalIF":3.1,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Serial vs parallel recall in the Blume-Every-Griffiths neural networks","authors":"Linda Albanese ,&nbsp;Andrea Alessandrelli ,&nbsp;Adriano Barra ,&nbsp;Emilio N.M. Cirillo","doi":"10.1016/j.physa.2026.131338","DOIUrl":"10.1016/j.physa.2026.131338","url":null,"abstract":"<div><div>Fully connected Blume–Emery–Griffiths neural networks performing pattern recognition and associative memory have been heuristically studied in the past (mainly via the replica trick and under the replica symmetric assumption) as generalization of the standard Hopfield reference. In these notes, at first, by relying upon Guerra interpolation, we re-obtain the existing picture rigorously. Next we show that, due to dilution in the patterns, these networks are able to switch from serial recall (where one pattern is retrieved per time) to parallel recall (where several patterns are retrieved at once) and the larger the dilution, the stronger this emerging multi-tasking capability. In particular, we inspect the regimes of <em>mild dilution</em> (where solely a low storage of pattern can be enabled) and <em>extreme dilution</em> (where a medium storage of patterns can be sustained) separately as they give rise to different outcomes: the former displays hierarchical recall (distributing the amplitudes of the retrieved signals with different amplitudes), the latter – instead – performs a equal-strength recall (where a <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span> fraction of all the patterns is simultaneously retrieved with the same amplitude per pattern).</div><div>Finally, in order to implement graded responses in the neurons, variations on theme obtained by enlarging the possible values of neural activity these neurons may sustain are also discussed generalizing the Ghatak–Sherrington model for <em>inverse freezing</em> in Hebbian terms.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"686 ","pages":"Article 131338"},"PeriodicalIF":3.1,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heterogeneous vehicle platooning in mixed traffic: Modeling and analysis using Markov chains","authors":"Zhen Qin ,&nbsp;Jianing Wang ,&nbsp;Lipo Mo ,&nbsp;Yu Zhang ,&nbsp;Dongfan Xie","doi":"10.1016/j.physa.2026.131358","DOIUrl":"10.1016/j.physa.2026.131358","url":null,"abstract":"<div><div>To address the rigid dependence of conventional platooning strategies on the continuous distribution of connected and autonomous vehicles (CAVs), this study proposes a hybrid platooning strategy that allows human-driven vehicles (HVs) to join platoons via CAVs, thereby alleviating the applicability issue of existing strategies in mixed traffic scenarios. Under the proposed strategy, a Markov chain model is proposed to dynamically capture vehicle types, platoon structures, and platooning behaviors . Through theoretical analysis and numerical simulations, the performance of the hybrid platooning strategy is compared with that of conventional platooning strategies. When the CAV penetration rate ranges from 0.4 to 0.7, the proposed hybrid strategy improves traffic efficiency by 3.4% to 4.6% over the conventional platooning strategy. Under highly dispersed vehicle arrival sequences, it increases lane capacity by up to 14%. Moreover, when the maximum platoon length reaches 50, the hybrid platooning strategy yields a capacity improvement of 5.09%.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"686 ","pages":"Article 131358"},"PeriodicalIF":3.1,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Robust two-dimensional platoon strategy for connected and automated vehicles","authors":"Jiahao Zhang ,&nbsp;Hongsheng Qi","doi":"10.1016/j.physa.2026.131324","DOIUrl":"10.1016/j.physa.2026.131324","url":null,"abstract":"<div><div>Platooning allows Connected and Automated Vehicles (CAVs) to operate efficiently and safely in coordinated formations. In mixed traffic with Human-Driven Vehicles (HDVs), platoon formation requires systematically generating and evaluating all feasible sequences of cooperative actions to account for HDVs’ unpredictable behaviors. Neglecting potential cooperative sequences can result in suboptimal platooning, unsafe maneuvers, or reduced energy efficiency. To address the challenge, this study firstly proposes a platoon scheme generation tree to identify all feasible platoon schemes for CAVs and guide the selection of the optimal one. Longitudinal and lateral control models are then designed to effectively manage the two-dimensional motion of CAVs toward the optimal platoon scheme. During the platooning process, the interaction between CAVs/HDVs are handled by a cooperative lane-changing strategy, incorporating gap negotiation, HDV behaviors prediction, and optimal cooperation timing for safe lateral merging in mixed traffic flow. Additionally, a two-dimensional driver model is employed to estimate HDV trajectories by a randomized kinematic intelligent driver model (KIDM). Case studies validate the proposed platoon methodology, demonstrating its effectiveness and robustness despite the influence of driving behaviors on platoon formation. The results indicate that this approach provides innovative insights and methods for implementing CAV platooning in practical mixed-traffic environments. This research indicates that a 2 % decrease in success rate of platoon formation for every 0.02 m increase in the lateral standard deviation of lateral movement of HDVs.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"686 ","pages":"Article 131324"},"PeriodicalIF":3.1,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cumulant expansions and the large deviation rate function","authors":"J.M. Rickman ,&nbsp;M.L. Comer ,&nbsp;J. Xu","doi":"10.1016/j.physa.2026.131332","DOIUrl":"10.1016/j.physa.2026.131332","url":null,"abstract":"<div><div>We show that that, by analogy with results from extreme-value theory, the rare events in a Gibbs distribution, as quantified by the exceedance of the distribution, may be expressed in terms of tail joint cumulants that systematically describe rare fluctuations in the tail of the distribution. A joint cumulant expansion based on histogram reweighting is then used to obtain the rate function from large deviation theory, a quantity that characterizes the exponential dependence of the tail of the distribution, for two prototypical systems, namely a 1-D ferromagnet in an external field and an atomistic model of a solid in the isobaric-isothermal ensemble. It is shown that this expansion permits one to capture the behavior of the rate function over a relatively wide range of parameter space from calculations done at one point in this space. Finally, we discuss the extension of this approach to multivariate distributions and suggest strategies for characterizing infrequent events described by the tails of such distributions.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"686 ","pages":"Article 131332"},"PeriodicalIF":3.1,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time delay effects on spatiotemporal pattern dynamics in directed networks","authors":"Zhao Song ,&nbsp;Ruihong Xue ,&nbsp;Xinyu Wang ,&nbsp;Xiangfeng Dai","doi":"10.1016/j.physa.2026.131350","DOIUrl":"10.1016/j.physa.2026.131350","url":null,"abstract":"<div><div>Pattern theory concerning networks has attracted substantial attention in recent years, proving its utility across diverse sub-disciplines, notably within the realm of reaction–diffusion (RD) systems. With real-world systems often characterized by directed connections, the traditional exploration of RD systems restricted to undirected networks has seamlessly extended to encompass directed networks. Prior studies have unveiled that in directed scenarios, the inherent asymmetry of the Laplacian matrix gives rise to intricate dispersion relations, thereby instigating the pursuit of further exploration and analysis. In this paper, we delve into time delay within RD systems operating on directed networks, which is not clearly revealed in previous work. Our investigations mainly focus on the emergence of spatially organized patterns resulting from the spatio-temporal dynamical processes. In detail, we linearize the RD system to derive the region of instability wherein patterns exhibit. This instability is time delay induced. Subsequent to this, we conduct extensive numerical simulations to illustrate wave patterns across different directed networks. Significantly, when the network connectivity is sufficiently high and the nodes achieve synchronized oscillations, we find that network properties — including the average degree and degree distribution — exert minimal influence on pattern formation. In contrast, time delay significantly shapes pattern periodicity. Furthermore, we establish a compelling correlation between time delay and pattern periodicity, elegantly captured by an exponential-type function.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"686 ","pages":"Article 131350"},"PeriodicalIF":3.1,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the dynamics of the q-Tsallis Gauss Iterated Map","authors":"Daniel Borin ,&nbsp;Matheus Rolim Sales ,&nbsp;Edson Denis Leonel ,&nbsp;Diego Fregolent Mendes de Oliveira","doi":"10.1016/j.physa.2026.131352","DOIUrl":"10.1016/j.physa.2026.131352","url":null,"abstract":"<div><div>We investigate the dynamical properties of a q-deformed generalization of the Gaussian iterated map, referred to as the q-Tsallis Gaussian Iterated Map, obtained by replacing the standard exponential with the Tsallis q-exponential function. Through bifurcation diagrams, Lyapunov exponent analysis, and isoperiodic diagrams, we characterize the transitions between periodic and chaotic regimes, as well as the emergence of multistability and bubbling phenomena, reveals that the introduction of the nonextensive parameter induces significant changes in the system’s dynamics.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"686 ","pages":"Article 131352"},"PeriodicalIF":3.1,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}