Diffusion under competing bulk and surface stopping mechanisms
Abstract
We investigate reflected diffusion in a bounded domain subject to two independent, competing stopping mechanisms: an exponentially distributed bulk lifetime of rate p and a surface reaction triggered when the boundary local time exceeds an independent exponential threshold of rate q. Denoting by T the stopping time and by L the acquired boundary local time at stopping, we derive their marginal distributions, joint Laplace transform, and complete hierarchy of mixed moments. These statistics are determined by the splitting probability ϕ that surface reaction occurs before bulk decay. In particular, we establish the identity pexpectT+qexpectL=1 and show that the cumulative risk pT+qL is exponentially distributed with unit rate. We further obtain equivalent representations of ϕ in terms of the Robin-Laplacian and the generalized Steklov spectra. Explicit results for a three-dimensional ball reveal how competing rates p,q control ϕ and the (T,L) statistics. Monte Carlo simulations test the universal cumulative-risk law.
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BibTeX
@misc{ye2026diffusion,
title = {{Diffusion under competing bulk and surface stopping mechanisms}},
author = {Yilin Ye},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.05247},
eprint = {2609.05247},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.05247},
}
RIS
TY - UNPB
TI - Diffusion under competing bulk and surface stopping mechanisms
AU - Yilin Ye
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2609.05247
UR - https://arxiv.org/abs/2609.05247
AB - We investigate reflected diffusion in a bounded domain subject to two independent, competing stopping mechanisms: an exponentially distributed bulk lifetime of rate p and a surface reaction triggered when the boundary local time exceeds an independent exponential threshold of rate q. Denoting by T the stopping time and by L the acquired boundary local time at stopping, we derive their marginal distributions, joint Laplace transform, and complete hierarchy of mixed moments. These statistics are determined by the splitting probability ϕ that surface reaction occurs before bulk decay. In particular, we establish the identity pexpectT+qexpectL=1 and show that the cumulative risk pT+qL is exponentially distributed with unit rate. We further obtain equivalent representations of ϕ in terms of the Robin-Laplacian and the generalized Steklov spectra. Explicit results for a three-dimensional ball reveal how competing rates p,q control ϕ and the (T,L) statistics. Monte Carlo simulations test the universal cumulative-risk law.
ER -