From microscopic dynamics to macroscopic behaviour in systems with two symmetric absorbing states
In this talk, I will present a general approach to study spin systems with two symmetric absorbing states. Starting from the microscopic dynamics on a square lattice, it is possible to derive a Langevin equation for the time evolution of the magnetization field, that explains coarsening properties of a wide range of nonlinear voter models. It turns out that the macroscopic behaviour only depends on the first derivatives of the spin-flip probabilities. To illustrate these results, I apply this approach to study models with intermediate states. Finally, I show how a mean-field approximation reveals the three types of transitions commonly observed in these systems -generalized voter, Ising and directed percolation.