Two-point Correlations and Critical Line of the Driven Ising Lattice Gas in a High Temperature Expansion

Based on a high temperature expansion, we compute the two-point correlation function and the critical line of an Ising lattice gas driven into a non-equilibrium steady state by a uniform bias E. The lowest nontrivial order already reproduces the key features, i.e., the discontinuity singularity of the structure factor and the (qualitative) E-dependence of the critical line. Our approach is easily generalized to other non-equilibrium lattice models and provides a simple analytic tool for the study of the high temperature phase and its boundaries.