Crossover to the stochastic Burgers equation for the WASEP with a slow bond
Abstract
We consider the weakly asymmetric simple exclusion process in the presence of a slow bond and starting from the invariant state, namely the Bernoulli product measure of parameter ρ∈(0,1). The rate of passage of particles to the right (resp. left) is 12+a2nγ (resp. 12−a2nγ) except at the bond of vertices {−1,0} where the rate to the right (resp. left) is given by α2nβ+a2nγ (resp. α2nβ−a2nγ). Above, α>0, γ≥β≥0, a≥0. For β<1, we show that the limit density fluctuation field is an Ornstein-Uhlenbeck process defined on the Schwartz space if γ>12, while for γ=12 it is an energy solution of the stochastic Burgers equation. For γ≥β=1, it is an Ornstein-Uhlenbeck process associated to the heat equation with Robin's boundary conditions. For γ≥β>1, the limit density fluctuation field is an Ornstein-Uhlenbeck process associated to the heat equation with Neumann's boundary conditions.