Superdiffusivity of occupation-time variance in 2-dimensional asymmetric processes with density 1/2

Abstract

We compute that the growth of the origin occupation-time variance up to time t in dimension d=2 with respect to asymmetric simple exclusion in equilibrium with density 1/2 is in a certain sense at least t(log(log t)) for general rates, and at least t(log t)^{1/2} for rates which are asymmetric only in the direction of one of the axes. These estimates are consistent with conjectures with respect to the transition function and variance of 'second-class' particles.