The all-time maximum for branching Brownian motion with absorption conditioned on long-time survival

par Pascal Maillard

mardi 13 juin 2023, 09:45 → 10:45 Europe/Paris

Amphi L. Schwartz

We consider branching Brownian motion in which initially there is one particle at $x$, particles produce a random number of offspring with mean $m+1$ at the time of branching events, and each particle branches at rate $\beta = 1/2m$.  Particles independently move according to Brownian motion with drift $-1$ and are killed at the origin.  It is well-known that this process eventually dies out with positive probability.  We condition this process to survive for an unusually large time $t$ and study the behavior of the process at small times $s \ll t$ using a spine decomposition.  We show, in particular, that the time when a particle gets furthest from the origin is of the order $t^{5/6}$. Joint work with Jason Schweinsberg (UC San Diego).