Superdiffusivity for Brownian motion in a Poissonian potential with long range correlation II: upper bound on the volume exponent

Abstract

This paper continues a study on trajectories of Brownian Motion in a field of soft trap whose radius distribution is unbounded. We show here for both point-to-point and point-to-plane model the volume exponent (the exponent associated to transversal fluctuation of the trajectories) is strictly less than one and give an explicit upper bound that depends on the parameters of the problem. In some specific cases, this upper bound matches the lower bound proved in the first part of this work and we get the exact value of the volume exponent.