A lattice gas coupled to two thermal reservoirs: Monte Carlo and field theoretic studies

We investigate the collective behavior of an Ising lattice gas, driven to n on-equilibrium steady states by being coupled to two thermal baths. Monte C arlo methods are applied to a two-dimensional system in which one of the ba ths is fixed at infinite temperature. Both genetic long range correlations in the disordered state and critical properties near the second order trans ition are measured. Anisotropic scaling, a key feature neat criticality, is used to extract T-c and some critical exponents. On the theoretical front, a continuum theory, in the spirit of Landau-Ginzburg, is presented. Being a renormalizable theory, its predictions call be computed by standard metho ds of epsilon -expansions and found to be consistent with simulation data. In particular, the critical behavior of this system belongs to a universali ty class which is quite different from the uniformly driven Ising model.