Response Function of Coarsening Systems

The response function of domain growth processes, and in particular the violation of the fluctuation-dissipation theorem, are studied both analytically and numerically. In the asymptotic limit of large times, the fluctuation-dissipation ratio $X$, which quantifies this violation, tends to one if $C>m^2$ and to zero if $C2$, and as $\ln (L(t))/L(t)$ for $d=2$. Numerical results confirming this analysis are presented.