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arXiv 1802.08618cond-mat.stat-mechcond-mat.dis-nnmath-phmath.MPmath.PR
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一维KPZ方程的$(- λH)^{5/2}$尾的简单推导

Simple derivation of the $(- λH)^{5/2}$ tail for the 1D KPZ equation

Alexandre Krajenbrink, Pierre Le Doussal

摘要:

研究了Kardar-Parisi-Zhang(KPZ)方程在$1+1$维数下的布朗和液滴初始条件下的长时间状态,并给出了$λH<0$负侧高度大偏差尾部的一个简单推导.我们发现,对于这两个初始条件,累积分布函数采取大偏差的形式,与尾部的$- \tilde s \gg 1$给出的$-\log \mathbb{P}\left(\frac{H}{t}<\tilde{s}\right)=t^2 \frac{4 }{15 π} (-\tilde{s})^{5/2} $。在两种初始条件下,在短时间内已经观察到了这种精确表达式,这表明这些大偏差在任何时候都是有效的。我们提出了两种方法来获得的结果(i)长时间估计使用Fredholm行列式公式和(ii)的行列式点过程的累积量的连续累积量的评价出现给大偏差率函数在大$\tilde s$展开的连续订单。本文还对低温下囚禁费米子的大偏差给出了解释。此外,我们进行了类似的计算KPZ方程在一个半空间液滴初始条件,并显示出相同的尾部,如上所述,与前因子$\frac{4}{15π}$取代$\frac{2}{15π}$。最后,可以扩展这些论证,以表明这条尾巴在任何时候都成立。这与先前在全空间问题的短时间限制内获得相同尾部的事实是一致的。

英文摘要:

We study the long-time regime of the Kardar-Parisi-Zhang (KPZ) equation in $1+1$ dimensions for the Brownian and droplet initial conditions and present a simple derivation of the tail of the large deviations of the height on the negative side $λH<0$. We show that for both initial conditions, the cumulative distribution functions take a large deviations form, with a tail for $- \tilde s \gg 1$ given by $-\log \mathbb{P}\left(\frac{H}{t}<\tilde{s}\right)=t^2 \frac{4 }{15 π} (-\tilde{s})^{5/2} $. This exact expression was already observed at small time for both initial conditions suggesting that these large deviations remain valid at all times. We present two methods to derive the result (i) long time estimate using a Fredholm determinant formula and (ii) the evaluation of the cumulants of a determinantal point process where the successive cumulants appear to give the successive orders of the large deviation rate function in the large $\tilde s$ expansion. An interpretation in terms of large deviations for trapped fermions at low temperature is also given. In addition, we perform a similar calculation for the KPZ equation in a half-space with a droplet initial condition, and show that the same tail as above arises, with the prefactor $\frac{4}{15π}$ replaced by $\frac{2}{15π}$. Finally, the arguments can be extended to show that this tail holds for all times. This is consistent with the fact that the same tail was obtained previously in the short time limit for the full-space problem.

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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