paper

Time scale separation in the low temperature East model: Rigorous results

arXiv:1212.2956 · doi:10.1088/1742-5468/2013/04/L04001

Abstract

We consider the non-equilibrium dynamics of the East model, a linear chain of 0-1 spins evolving under a simple Glauber dynamics in the presence of a kinetic constraint which forbids flips of those spins whose left neighbour is 1. We focus on the glassy effects caused by the kinetic constraint as , where is the equilibrium density of the 0's. Specifically we analyse time scale separation and dynamic heterogeneity, i.e. non-trivial spatio-temporal fluctuations of the local relaxation to equilibrium, one of the central aspects of glassy dynamics. For any mesoscopic length scale , , we show that the characteristic time scale associated to two length scales and are indeed separated by a factor , , provided that is large enough independently of . In particular, the evolution of mesoscopic domains, i.e. maximal blocks of the form , occurs on a time scale which depends sharply on the size of the domain, a clear signature of dynamic heterogeneity. Finally we show that no form of time scale separation can occur for , i.e. at the equilibrium scale , contrary to what was previously assumed in the physical literature based on numerical simulations.

6 pages, 0 figures; clarified q dependence of bounds, results unchanged

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