Out-of-equilibrium relaxation of a time-dependent effective temperature

Constitutive equations are proposed for the relaxation of a glassy material in contact with a thermal reservoir. The dynamics of a single state variable, identified as an effective temperature accounts for the emergence of glassy behavior at low bath temperature. Memory effect in cooling/reheating experiments are discussed along with several aspects of the response to shear: aging of the response to step strains, response to oscillatory forcing, and steady rheology.