Aging in out-of-equilibrium dynamics of models for granular media

In the framework of recently introduced frustrated lattice gas models, we study the out-of-equilibrium dynamical processes during the compaction in granular media. We find irreversible-reversible cycles in agreement with recent experimental observations, along which we can individuate an equivalent "glass transition," Gamma(g). In analogy with the phenomenology of glassy systems we find aging effects during the compaction process. In particular, we find that the two-time density correlation function C(t, t') asymptotically scales as a function of the single variable In(t')/ln(t).