Annealed survival asymptotics for Brownian motion in a scaled Poissonian potential

We consider d-dimensional Brownian motion evolving in a scaled Poissonian potential βϕ−2(t)V, where β>0 is a constant, ϕ is the scaling function which typically tends to infinity, and V is obtained by translating a fixed non-negative compactly supported shape function to all the particles of a d-dimensional Poissonian point process. We are interested in the large t behavior of the annealed partition sum of Brownian motion up to time t under the influence of the natural Feynman–Kac weight associated to βϕ−2(t)V. We prove that for d⩾2 there is a critical scale ϕ and a critical constant βc(d)>0 such that the annealed partition sum undergoes a phase transition if β crosses βc(d). In d=1 this picture does not hold true, which can formally be interpreted that on the critical scale ϕ we have βc(1)=0.