Law of the iterated logarithm for supercritical non-local spatial branching processes

Fuente: arXiv
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Main Authors: Hou, Haojie, Yang, Ting
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Published: 2025
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author Hou, Haojie
Yang, Ting
author_facet Hou, Haojie
Yang, Ting
contents Suppose that $X=(X_{t})_{t\ge 0}$ is either a general supercritical non-local branching Markov process, or a general supercritical non-local superprocess, on a Luzin space. Here, by ``supercritical" we mean that the mean semigroup of $X$ exhibits a Perron-Frobenius type behaviour with a positive principal eigenvalue. In this paper, we study the almost sure behaviour of a family of martingales naturally associated with the real or complex-valued eigenpairs of the mean semigroup. Under a fourth-moment condition, we establish limit theorems of the iterated logarithm type for these martingales. In particular, we discover three regimes, each resulting in different scaling factors and limits. Furthermore, we obtain a law of the iterated logarithm for the linear functional $\langle \mathrm{Re}(f),X_{t}\rangle$ where $f$ is a sum of finite terms of eigenfunctions and $\mathrm{Re}(f)$ denotes its real part. In the context of branching Markov processes, our results improve on existing literature by complementing the known results for multitype branching processes in Asmussen [Trans. Amer. Math. Soc. 231 (1) (1977) 233--248] and generalizing the recent work of Hou, Ren and Song [arXiv: 2505.12691] to allow for non-local branching mechanism and non-symmetric spatial motion. For superprocesses, as far as we know, our results are new.
format Preprint
id arxiv_https___arxiv_org_abs_2508_12772
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Law of the iterated logarithm for supercritical non-local spatial branching processes
Hou, Haojie
Yang, Ting
Probability
60J80, 60J68, 60F15, 60J35
Suppose that $X=(X_{t})_{t\ge 0}$ is either a general supercritical non-local branching Markov process, or a general supercritical non-local superprocess, on a Luzin space. Here, by ``supercritical" we mean that the mean semigroup of $X$ exhibits a Perron-Frobenius type behaviour with a positive principal eigenvalue. In this paper, we study the almost sure behaviour of a family of martingales naturally associated with the real or complex-valued eigenpairs of the mean semigroup. Under a fourth-moment condition, we establish limit theorems of the iterated logarithm type for these martingales. In particular, we discover three regimes, each resulting in different scaling factors and limits. Furthermore, we obtain a law of the iterated logarithm for the linear functional $\langle \mathrm{Re}(f),X_{t}\rangle$ where $f$ is a sum of finite terms of eigenfunctions and $\mathrm{Re}(f)$ denotes its real part. In the context of branching Markov processes, our results improve on existing literature by complementing the known results for multitype branching processes in Asmussen [Trans. Amer. Math. Soc. 231 (1) (1977) 233--248] and generalizing the recent work of Hou, Ren and Song [arXiv: 2505.12691] to allow for non-local branching mechanism and non-symmetric spatial motion. For superprocesses, as far as we know, our results are new.
title Law of the iterated logarithm for supercritical non-local spatial branching processes
topic Probability
60J80, 60J68, 60F15, 60J35
url https://arxiv.org/abs/2508.12772