Abstract : We study the non-equilibrium time evolution of the classical XY spin model in two dimensions.The two-time autocorrelation and linear response functions are considered for systems initially preparedin a high temperature state and in a completely ordered state. After a quench into the critical phase, we determine, via Monte Carlosimulations, the time-evolution of these quantities and extract the temperature dependence of the slope of the parametric plotsusceptibility/correlation in the asymptotic regime. This slope is usually identified with the infinite fluctuation-dissipation ratiowhich measures the violation to the equilibrium fluctuation-dissipation theorem. However, a direct measure of this ratio leads to a vanishingvalue.
