The critical velocity of the bullet process appears pathwise

Fuente: arXiv
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Main Author: Meisel, Josh
Format: Preprint
Published: 2025
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author Meisel, Josh
author_facet Meisel, Josh
contents In the bullet process, a gun fires bullets in the same direction at independent random speeds, and with independent random time delays between firings. When two bullets collide, they vanish. The critical velocity $v_c$ is the slowest speed the first bullet can take and still have positive probability of surviving forever. We characterize the critical velocity via a random variable determined by the sequence of speeds and delays, which we show almost surely equals $v_c$. In turn we prove other facts about the process, including that infinitely many bullets survive when the velocity distribution has finite support. Along the way we answer a question from Broutin--Marckert (2020), showing that if a bullet survives, it does so in all but finitely many truncations of the process.
format Preprint
id arxiv_https___arxiv_org_abs_2501_14219
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The critical velocity of the bullet process appears pathwise
Meisel, Josh
Probability
60K35
In the bullet process, a gun fires bullets in the same direction at independent random speeds, and with independent random time delays between firings. When two bullets collide, they vanish. The critical velocity $v_c$ is the slowest speed the first bullet can take and still have positive probability of surviving forever. We characterize the critical velocity via a random variable determined by the sequence of speeds and delays, which we show almost surely equals $v_c$. In turn we prove other facts about the process, including that infinitely many bullets survive when the velocity distribution has finite support. Along the way we answer a question from Broutin--Marckert (2020), showing that if a bullet survives, it does so in all but finitely many truncations of the process.
title The critical velocity of the bullet process appears pathwise
topic Probability
60K35
url https://arxiv.org/abs/2501.14219