First passage times with fast immigration

Fuente: arXiv
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Auteurs principaux: Tung, Hwai-Ray, Lawley, Sean D
Format: Preprint
Publié: 2025
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author Tung, Hwai-Ray
Lawley, Sean D
author_facet Tung, Hwai-Ray
Lawley, Sean D
contents Many scientific questions can be framed as asking for a first passage time (FPT), which generically describes the time it takes a random "searcher" to find a "target." The important timescale in a variety of biophysical systems is the time it takes the fastest searcher(s) to find a target out of many searchers. Previous work on such fastest FPTs assumes that all searchers are initially present in the domain, which makes the problem amenable to extreme value theory. In this paper, we consider an alternative model in which searchers progressively enter the domain at a constant "immigration" rate. In the fast immigration rate limit, we determine the probability distribution and moments of the $k$-th fastest FPT. Our rigorous theory applies to many models of stochastic motion, including random walks on discrete networks and diffusion on continuous state spaces. Mathematically, our analysis involves studying the extrema of an infinite sequence of random variables which are both not independent and not identically distributed. Our results constitute a rare instance in which extreme value statistics can be determined exactly for strongly correlated random variables.
format Preprint
id arxiv_https___arxiv_org_abs_2502_10915
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle First passage times with fast immigration
Tung, Hwai-Ray
Lawley, Sean D
Probability
60G70, 92B99, 60J60
Many scientific questions can be framed as asking for a first passage time (FPT), which generically describes the time it takes a random "searcher" to find a "target." The important timescale in a variety of biophysical systems is the time it takes the fastest searcher(s) to find a target out of many searchers. Previous work on such fastest FPTs assumes that all searchers are initially present in the domain, which makes the problem amenable to extreme value theory. In this paper, we consider an alternative model in which searchers progressively enter the domain at a constant "immigration" rate. In the fast immigration rate limit, we determine the probability distribution and moments of the $k$-th fastest FPT. Our rigorous theory applies to many models of stochastic motion, including random walks on discrete networks and diffusion on continuous state spaces. Mathematically, our analysis involves studying the extrema of an infinite sequence of random variables which are both not independent and not identically distributed. Our results constitute a rare instance in which extreme value statistics can be determined exactly for strongly correlated random variables.
title First passage times with fast immigration
topic Probability
60G70, 92B99, 60J60
url https://arxiv.org/abs/2502.10915