Linear response to perturbation of non-exponential renewal processes
  We study the linear response of a two-state stochastic process, obeying renewal condition, by means of a stochastic rate equation equivalent to a master equation with infinite memory. We show that the condition of perennial aging makes the response to coherent perturbation vanish in the long-time limit. 
Francesco Barbi, Mauro Bologna and Paolo Grigolini