First-passage statistics of random walks: a general approach via Riemann-Hilbert problems

Fuente: arXiv
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Autores principales: Radice, Mattia, Cristadoro, Giampaolo
Formato: Preprint
Publicado: 2025
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author Radice, Mattia
Cristadoro, Giampaolo
author_facet Radice, Mattia
Cristadoro, Giampaolo
contents We study first-passage statistics for one-dimensional random walks $S_n$ with independent and identically distributed jumps starting from the origin. We focus on the joint distribution of the first-passage time $τ_b$ and first-passage position $S_{τ_b}$ beyond a threshold $b\geq0$, as well as the distribution of $S_n$ for the walks that do not cross $b$ up to step $n$. By solving suitable Riemann-Hilbert problems, we are able to obtain exact and semi-explicit general formulae for the quantities of interest. Notably, such formulae are written solely in terms of the characteristic function of the jumps. In contrast with previous results, our approach is universally valid, applicable to both continuous and discrete, symmetric and asymmetric jump distributions. We complement our theoretical findings with explicit examples.
format Preprint
id arxiv_https___arxiv_org_abs_2507_11196
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle First-passage statistics of random walks: a general approach via Riemann-Hilbert problems
Radice, Mattia
Cristadoro, Giampaolo
Statistical Mechanics
We study first-passage statistics for one-dimensional random walks $S_n$ with independent and identically distributed jumps starting from the origin. We focus on the joint distribution of the first-passage time $τ_b$ and first-passage position $S_{τ_b}$ beyond a threshold $b\geq0$, as well as the distribution of $S_n$ for the walks that do not cross $b$ up to step $n$. By solving suitable Riemann-Hilbert problems, we are able to obtain exact and semi-explicit general formulae for the quantities of interest. Notably, such formulae are written solely in terms of the characteristic function of the jumps. In contrast with previous results, our approach is universally valid, applicable to both continuous and discrete, symmetric and asymmetric jump distributions. We complement our theoretical findings with explicit examples.
title First-passage statistics of random walks: a general approach via Riemann-Hilbert problems
topic Statistical Mechanics
url https://arxiv.org/abs/2507.11196