Decay of covariances, uniqueness of ergodic component and scaling limit   for a class of \nabla\phi systems with non-convex potential
  We consider a gradient interface model on the lattice with interaction potential which is a nonconvex perturbation of a convex potential. Using a technique which decouples the neighboring vertices sites into even and odd vertices, we show for a class of non-convex potentials: the uniqueness of ergodic component for \nabla\phi-Gibbs measures, the decay of covariances, the scaling limit and the strict convexity of the surface tension. 
Codina Cotar and Jean-Dominique Deuschel