Lattice Independent Approach to Thermal Phase Mixing

We show how to achieve lattice-spacing independent results in numerical simulations of finite-temperature stochastic scalar field theories. We generalize the previous approach of hep-lat/9607026 by obtaining results which are independent of the renormalization scale. As an application of our method, we examine thermal phase mixing in the context of Ginzburg-Landau models with short-range interactions. In particular, we obtain the lattice-spacing and renormalization-scale independent critical value of the control parameter which determines the free-energy barrier between the two low-temperature phases. We also propose a simple procedure to extract the critical value of control parameters for different choices of lattice spacing.