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arXiv 1408.4479cond-mat.stat-mechmath-phmath.MPnlin.CD
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Lévy游动的无穷稠密性

Infinite densities for Lévy walks

Adi Rebenshtok, Sergey Denisov, Peter Hanggi, Eli Barkai

摘要:

在许多系统中,粒子的运动表现出类似于随机扩散事件和类似于弹道运动的周期之间的混合。在许多情况下,这样的系统表现出强烈的反常扩散,其中具有低于临界值$q_c$的$q$的低阶矩$< |x(t)|^q >$表现出扩散标度,而对于$q>q_c$则出现弹道标度。混合动力学构成了一个理论挑战,因为它不属于一个独特的运动类别,例如,已知的扩散方程和中心极限定理不能描述这两个方面。在本文中,我们解决了这个问题诉诸无穷密度的概念。利用广泛适用的Lévy walk模型,我们得到了相应的非归一化密度的一般表达式,它完全由粒子速度分布、反常扩散指数$α$和扩散系数$K_α$决定.我们解释了如何无限的密度发挥了核心作用,在描述动态的一个大类的物理过程,并讨论如何可以从实验或数值数据进行评估。

英文摘要:

Motion of particles in many systems exhibits a mixture between periods of random diffusive like events and ballistic like motion. In many cases, such systems exhibit strong anomalous diffusion, where low order moments $< |x(t)|^q >$ with $q$ below a critical value $q_c$ exhibit diffusive scaling while for $q>q_c$ a ballistic scaling emerges. The mixed dynamics constitutes a theoretical challenge since it does not fall into a unique category of motion, e.g., the known diffusion equations and central limit theorems fail to describe both aspects. In this paper we resolve this problem by resorting to the concept of infinite density. Using the widely applicable Lévy walk model, we find a general expression for the corresponding non-normalized density which is fully determined by the particles velocity distribution, the anomalous diffusion exponent $α$ and the diffusion coefficient $K_α$. We explain how infinite densities play a central role in the description of dynamics of a large class of physical processes and discuss how they can be evaluated from experimental or numerical data.

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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