Local times and capacity for transient branching random walks

Abstract

41p.International audienceWe consider branching random walks on the Euclidean lattice in dimensions five and higher. In this non-Markovian setting, we first obtain a relationship between the equilibrium measure and Green's function, in the form of an approximate last passage decomposition. Secondly, we obtain exponential moment bounds for functionals of the branching random walk, under optimal condition. As a corollary we obtain an approximate variational characterisation of the branching capacity. We finally derive upper bounds involving the branching capacity for the tail of the time spent in an arbitrary finite collection of balls. This generalises the results of [AHJ21] and [AS22] for d ≥ 5. For random walks, the analogous tail estimates have been instrumental tools for tackling deviations problems on the range, related to folding of the walk