Metastable states and space-time phase transitions in a spin-glass model.

We study large deviations of the dynamical activity in the random orthogonal model. This is a fully connected spin-glass model with one-step replica symmetry-breaking behavior, consistent with the random first-order transition scenario for structural glasses. We show that this model displays dynamical (space-time) phase transitions between active and inactive phases, as demonstrated by singularities in large deviation functions. We argue that such transitions are generic in systems with long-lived metastable states.