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arXiv 1609.00264cond-mat.stat-mech
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起伏界面的局部平均高度分布

Local average height distribution of fluctuating interfaces

Naftali R. Smith, Baruch Meerson, Pavel V. Sasorov

摘要:

生长表面的高度波动可以用有限时刻空间点上高度的概率分布来表征。近年来,关于$1+1$维Kardar-Parisi-Zhang(KPZ)方程的这个量的研究取得了令人瞩目的进展.在这里,我们注意到,在临界尺寸或以上,有限时间的一点高度分布在广泛的线性表面生长模型中是不好定义的,除非模型在小尺度下正则化。通过依赖于系统的小尺度截断的正则化导致普适性的部分损失。作为一种可能的替代方案,我们引入了\emph{local average height}。对于线性模型,这个量的概率密度在任何维度上都是明确定义的。这些模型的弱噪声理论(WNT)产生的“最佳路径”的界面上的局部平均高度的非平衡波动的条件。作为一个例子,我们考虑保守的爱德华-威尔金森(EW)方程,其中,没有正则化,有限时间的一点高度分布在所有的物理维度是不明确的。我们还确定了一个密切相关的问题的有限时间\emph{height-difference}分布的非保守EW方程在$1+1$维的界面的最佳路径。最后,我们讨论了$2+1$维(非正则化)KPZ方程中有限时间单点高度分布的UV突变。

英文摘要:

Height fluctuations of growing surfaces can be characterized by the probability distribution of height in a spatial point at a finite time. Recently there has been spectacular progress in the studies of this quantity for the Kardar-Parisi-Zhang (KPZ) equation in $1+1$ dimensions. Here we notice that, at or above a critical dimension, the finite-time one-point height distribution is ill-defined in a broad class of linear surface growth models, unless the model is regularized at small scales. The regularization via a system-dependent small-scale cutoff leads to a partial loss of universality. As a possible alternative, we introduce a \emph{local average height}. For the linear models the probability density of this quantity is well-defined in any dimension. The weak-noise theory (WNT) for these models yields the "optimal path" of the interface conditioned on a non-equilibrium fluctuation of the local average height. As an illustration, we consider the conserved Edwards-Wilkinson (EW) equation, where, without regularization, the finite-time one-point height distribution is ill-defined in all physical dimensions. We also determine the optimal path of the interface in a closely related problem of the finite-time \emph{height-difference} distribution for the non-conserved EW equation in $1+1$ dimension. Finally, we discuss a UV catastrophe in the finite-time one-point distribution of height in the (non-regularized) KPZ equation in $2+1$ dimensions.

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