  The configurational de-correlation in an aging system is attributed to
irreversible intermittent rearrangements, which are described as a Poisson
process with average $\propto \ln(1 + t/t_w)$, where $t$ is the observation
time and $t_w$ is the age [P. Sibani and H.J. Jensen, Europhys. Lett. 69,
2005]. On this basis, we obtain a simple model for the off-equilibrium aging
behavior of the autocorrelation: the average autocorrelation decays
algebraically, and its shifted and rescaled probability density function (PDF)
has a Gumbel-like shape which approaches a Gaussian at large times and becomes
sharp in the thermodynamic limit. The model properties are tested against
simulations of the Edwards-Anderson spin glass, and are in reasonable agreement
with other available data.
