Localisation in the Bouchaud-Anderson Model

Abstract: It is well-known that both branching random walk models and trap models can exhibit intermittency and localisation phenomena; the prototypical examples being the parabolic Anderson and Bouchaud trap models respectively. Our aim is to investigate how these localisation phenomena interact. To do so, we study a hybrid model combining the dynamics of both the parabolic Anderson and the Bouchaud trap models; more precisely, we consider a variant of the parabolic Anderson model in which the underlying random walk driving the model is replaced with the Bouchaud trap model. In this initial study, we consider the model where the potential field distribution has Weibull tail decay and the trap distribution is bounded away from zero. In dimension one, we further assume that the trap distribution decays sufficiently fast. Under these conditions, we show that the localisation effects in the hybrid model are strongly dominated by the influence of the parabolic Anderson model; the Bouchaud trap model plays at most a minor role. Moreover, we distinguish regimes in which the Bouchaud trap model acts to strengthen or weaken the localisation effects due to the parabolic Anderson model, and also identify regimes in which the Bouchaud trap model has no influence at all on localisation in the hybrid model.