Fluctuation dissipation ratio in the one-dimensional kinetic Ising model

The exact relation between the response function R(t,t') and the two time correlation function C(t,t') is derived analytically in the one-dimensional kinetic Ising model subjected to a temperature quench. The fluctuation dissipation ratio X(t,t') is found to depend on time through C(t,t') in the time region where scaling C(t,t') = f(t/t') holds. The crossover from the nontrivial form X[C(t,t')] to X(t,t') = 1 takes place as the waiting time t(w) is increased from below to above the equilibration time t(eq).