Behaviors near explosion of nonlinear CSBPs with regularly varying mechanisms

Fuente: arXiv
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Autori principali: Li, Bo, Foucart, Clément, Zhou, Xiaowen
Natura: Preprint
Pubblicazione: 2024
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author Li, Bo
Foucart, Clément
Zhou, Xiaowen
author_facet Li, Bo
Foucart, Clément
Zhou, Xiaowen
contents We study the explosion phenomenon of nonlinear continuous-state branching processes (nonlinear CSBPs). First an explicit integral test for explosion is designed when the rate function does not increase too fast. We then exhibit three different regimes of explosion when the branching mechanism and the rate function are regularly varying respectively at $0$ and $\infty$ with indices $α$ and $β$ such that $0\leqα\leq β$ and $β>0$. If $α>0$ then the renormalisation of the process before its explosion is linear. When moreover $α\neq β$, the limiting distribution is that of a ratio of two independent random variables whose laws are identified. When $α=β$, the limiting random variable shrinks to a constant. Last, when $α=0$, i.e. the branching mechanism is slowly varying at $0$, the process is studied with the help of a nonlinear renormalisation. The limiting distribution becomes the inverse uniform distribution. This complements results known in the case of finite mean and provides new insight for the classical explosive continuous-state branching processes (for which $β=1$).
format Preprint
id arxiv_https___arxiv_org_abs_2404_06145
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Behaviors near explosion of nonlinear CSBPs with regularly varying mechanisms
Li, Bo
Foucart, Clément
Zhou, Xiaowen
Probability
60J25, 60J80
We study the explosion phenomenon of nonlinear continuous-state branching processes (nonlinear CSBPs). First an explicit integral test for explosion is designed when the rate function does not increase too fast. We then exhibit three different regimes of explosion when the branching mechanism and the rate function are regularly varying respectively at $0$ and $\infty$ with indices $α$ and $β$ such that $0\leqα\leq β$ and $β>0$. If $α>0$ then the renormalisation of the process before its explosion is linear. When moreover $α\neq β$, the limiting distribution is that of a ratio of two independent random variables whose laws are identified. When $α=β$, the limiting random variable shrinks to a constant. Last, when $α=0$, i.e. the branching mechanism is slowly varying at $0$, the process is studied with the help of a nonlinear renormalisation. The limiting distribution becomes the inverse uniform distribution. This complements results known in the case of finite mean and provides new insight for the classical explosive continuous-state branching processes (for which $β=1$).
title Behaviors near explosion of nonlinear CSBPs with regularly varying mechanisms
topic Probability
60J25, 60J80
url https://arxiv.org/abs/2404.06145