Extremal fluctuations and intermittency in aging glassy systems

The talk considers the statistics of the amount of heat $Q(\delta t, t, t_w$ exchanged over a short interval $\delta t$ between a glassy system and its thermal bath.

The PDF of the heat exchange is studied by numerical simulations of a short range spin-glass model. Its form qualitatively depends on the relative magnitude of the sampling interval $t$ and the system age $t_w$: for $t< We argue that these events corresponds to the irreversible release of the excess energy initially trapped by the quench, and show that their statistics can be interpreted using a recently advanced theory (P. Sibani and J. Dall, Europhys. Lett. 64, 8-14, 2003) of non-stationary irreversible relaxation in glassy systems. The key theoretical assumption there is that extremal energy fluctuations within metastable regions trigger the irreversible drift in glassy dynamics.

If time permits, the relationship with recent experimental results on intermittency in aging gels and polymer glasses will also be discussed.