Universal decay of classical Loschmidt echo of neutrally stable but   mixing dynamics
  We provide analytical and numerical evidence that classical mixing systems which lack exponential sensitivity on initial conditions, exhibit universal decay of Loschmidt echo which turns out to be a function of a single scaled time variable delta^(2/5)t, where delta is the strength of perturbation. The role of dynamical instability and entropy production is discussed. 
Giulio Casati, Tomaz Prosen, Jinghua Lan, Baowen Li