Monte Carlo simulations of the violation of the fluctuation-dissipation theorem in domain growth processes

Numerical simulations of various domain growth systems are reported in order to compute the parameter describing the violation of fluctuation-dissipation theorem (FDT) in aging phenomena. We compute two-time correlation and response functions and find that, as expected from the exact solution of a certain mean-field model [equivalent to the O(N) model in three dimensions, in the limit of N going to infinity], this parameter is equal to one (no violation of FDT) in the quasiequilibrium regime (shea separation of times), and zero in the aging regime.