Equivalence of mean-field avalanches and branching diffusions: from the Brownian force model to the super-Brownian motion

Abstract

We point out that the mean-field theory of avalanches in the dynamics of elastic interfaces, the so-called Brownian force model (BFM) developed recently in non-equilibrium statistical physics, is equivalent to the so-called super-Brownian motion (SBM) developed in probability theory, a continuum limit of branching processes related to space-embedded Galton–Watson trees. In particular the exact solvability property recently (re-)discovered from the field theory in mean-field avalanches (the ‘instanton equation’) maps onto the so-called Dawson–Watanabe 1968 duality property. In the light of this correspondence we compare the results obtained independently in the two fields, and transport some of them from one field to the other. In particular, we discuss a scaling limit of the branching Brownian motion which maps onto the continuum field theory of mean-field avalanches.