1206.7002 (Wahb Ettoumi et al.)

Action diffusion and lifetimes of quasistationary states in the
Hamiltonian Mean Field model    [PDF]

Wahb Ettoumi, Marie-Christine Firpo

Out-of-equilibrium quasistationary states (QSSs) are one of the signatures of a broken ergodicity in long-range interacting systems. For the widely studied Hamiltonian Mean-Field model, the lifetime of some QSSs has been shown to diverge with the number N of degrees of freedom with a puzzling N^1.7 scaling law, contradicting the otherwise widespread N scaling law. It is shown here that the former peculiar scaling arises from the locality properties of the dynamics captured through the computation of the diffusion coefficient in terms of the action variable. Estimating the QSS lifetime by a mean first passage time successfully reproduces the non-trivial scaling at stake here.

View original: http://arxiv.org/abs/1206.7002