Exponential moments of truncated branching random walk martingales

Fuente: arXiv
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Main Authors: Ma, Heng, Maillard, Pascal
Format: Preprint
Published: 2025
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author Ma, Heng
Maillard, Pascal
author_facet Ma, Heng
Maillard, Pascal
contents For a branching random walk that drifts to infinity, consider its Malthusian martingale, i.e.~the additive martingale with parameter $θ$ being the smallest root of the characteristic equation. When particles are killed below the origin, we show that the limit of this martingale admits an exponential tail, contrary to the case without killing, where the tail is polynomial. In the critical case, where the characteristic equation has a single root, the same holds for the (truncated) derivative martingale, as we show. This study is motivated by recent work on first passage percolation on Erdős-Rényi graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2504_20963
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exponential moments of truncated branching random walk martingales
Ma, Heng
Maillard, Pascal
Probability
Primary 60J80, 60G55, Secondary 60G70, 92D25
For a branching random walk that drifts to infinity, consider its Malthusian martingale, i.e.~the additive martingale with parameter $θ$ being the smallest root of the characteristic equation. When particles are killed below the origin, we show that the limit of this martingale admits an exponential tail, contrary to the case without killing, where the tail is polynomial. In the critical case, where the characteristic equation has a single root, the same holds for the (truncated) derivative martingale, as we show. This study is motivated by recent work on first passage percolation on Erdős-Rényi graphs.
title Exponential moments of truncated branching random walk martingales
topic Probability
Primary 60J80, 60G55, Secondary 60G70, 92D25
url https://arxiv.org/abs/2504.20963