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arXiv 1201.5306cond-mat.stat-mech
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拟决定极限的标度理论

A scaling theory for the quasi-deterministic limit

David A. Kessler, Nadav M. Shnerb

摘要:

确定性速率方程在随机相互作用粒子系统的研究中有着广泛的应用。这种方法假设当粒子数$N$较大时,与基本成分的离散性相关的固有噪声可以忽略。因此,当随机波动的幅度与种群的规模相当时,它在接近灭绝过渡时失败了。在这里,我们提出了一个一般的标度理论的空间扩展系统的过渡制度。两个基本模型的平衡外相变被认为是:易感-感染-易感(SIS),属于定向渗流等价类,和易感-感染-扩散(SIR)模型属于动态渗流类。实施金兹伯格标准,我们表明,波动主导的区域尺度的宽度,如$N^{-κ}$,其中$N$是每个站点和$κ= 2/(d_u-d)$,$d_u$的个人数量是上临界尺寸。其他指数控制的方法确定性的限制取决于$κ$。该理论是支持广泛的数值模拟系统的各种维度的结果。

英文摘要:

Deterministic rate equations are widely used in the study of stochastic, interacting particles systems. This approach assumes that the inherent noise, associated with the discreteness of the elementary constituents, may be neglected when the number of particles $N$ is large. Accordingly, it fails close to the extinction transition, when the amplitude of stochastic fluctuations is comparable with the size of the population. Here we present a general scaling theory of the transition regime for spatially extended systems. Two fundamental models for out-of-equilibrium phase transitions are considered: the Susceptible-Infected-Susceptible (SIS) that belongs to the directed percolation equivalence class, and the Susceptible-Infected-Recovered (SIR) model belonging to the dynamic percolation class. Implementing the Ginzburg criteria we show that the width of the fluctuation-dominated region scales like $N^{-κ}$, where $N$ is the number of individuals per site and $κ= 2/(d_u-d)$, $d_u$ is the upper critical dimension. Other exponents that control the approach to the deterministic limit are shown to depend on $κ$. The theory is supported by the results of extensive numerical simulations for systems of various dimensionalities.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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