ul 2 00 1 Quenches and crunchs : Does the system explore in aging the same part of the configuration space explored in equilibrium ?

Numerical studies are providing novel information on the physical processes associated to physical aging. The process of aging has been shown to consist in a slow process of explorations of deeper and deeper minima of the system potential energy surface. In this article we compare the properties of the basins explored in equilibrium with those explored during the aging process both for sudden temperature changes and for sudden density changes. We find that the hypothesis that during the aging process the system explores the part of the configuration space explored in equilibrium holds only for shallow quenches or for the early aging dynamics. At longer times, systematic deviations are observed. In the case of crunches, such deviations are much more apparent.