تقرير
Particle-number distribution in large fluctuations at the tip of branching random walks
| العنوان: | Particle-number distribution in large fluctuations at the tip of branching random walks |
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| المؤلفون: | Mueller, A. H., Munier, S. |
| المصدر: | Phys. Rev. E 102, 022104 (2020) |
| سنة النشر: | 2019 |
| المجموعة: | Condensed Matter High Energy Physics - Phenomenology |
| مصطلحات موضوعية: | Condensed Matter - Statistical Mechanics, High Energy Physics - Phenomenology |
| الوصف: | We investigate properties of the particle distribution near the tip of one-dimensional branching random walks at large times $t$, focusing on unusual realizations in which the rightmost lead particle is very far ahead of its expected position - but still within a distance smaller than the diffusion radius $\sim\sqrt{t}$. Our approach consists in a study of the generating function $G_{\Delta x}(\lambda)=\sum_n \lambda^n p_n(\Delta x)$ for the probabilities $p_n(\Delta x)$ of observing $n$ particles in an interval of given size $\Delta x$ from the lead particle to its left, fixing the position of the latter. This generating function can be expressed with the help of functions solving the Fisher-Kolmogorov-Petrovsky-Piscounov (FKPP) equation with suitable initial conditions. In the infinite-time and large-$\Delta x$ limits, we find that the mean number of particles in the interval grows exponentially with $\Delta x$, and that the generating function obeys a nontrivial scaling law, depending on $\Delta x$ and $\lambda$ through the combined variable $[\Delta x-f(\lambda)]^{3}/\Delta x^2$, where $f(\lambda)\equiv -\ln(1-\lambda)-\ln[-\ln(1-\lambda)]$. From this property, one may conjecture that the growth of the typical particle number with the size of the interval is slower than exponential, but, surprisingly enough, only by a subleading factor at large $\Delta x$. The scaling we argue is consistent with results from a numerical integration of the FKPP equation. Comment: 24 pages, 4 figures. v2: Minor changes, including a few extra references; To appear in Phys. Rev. E |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1103/PhysRevE.102.022104 |
| URL الوصول: | http://arxiv.org/abs/1910.06382 |
| رقم الأكسشن: | edsarx.1910.06382 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1103/PhysRevE.102.022104 |
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