Abstract
Our theoretical understanding of the glass transition remains incomplete. The microscopic origin of the dynamic slowing down can be explained by the presence of spatial heterogeneities which have been observed experimentally and numerically in various glass-formers. In this work, we characterize the dynamical heterogeneities during a nonequilibrium dynamics. Our analysis is based on detailed theoretical and numerical results for the activated aging regime of simple kinetically constrained models. We shown that fragile glasses close to their glass transition exhibit a lifetime of dynamic heterogeneities larger than their relaxation time. We find also that the aging dynamics of these models can be described in term of very special class of random walks. Moreover, the measurement of the violation of the fluctuation-dissipation theorem leads to negative effective temperature which is a direct consequence of the thermally activated dynamics.