A cluster expansion for stochastic lattice fields

A Langevin equation of Landau-Ginzburg type for the stochastic dynamics of a scalar field on a lattice is studied. A cluster expansion is developed for this problem which converges for large mass. As a consequence, one establishes uniformly in the volume: (a) exponential decay of correlations in space and time, and (b) exponential approach to equilibrium for a class of nearby initial distributions.