Mode-coupling theory for aging in active glasses: relaxation dynamics and evolution towards steady state.

Aging refers to the evolution of system properties with waiting time tw. It is a key feature of glassy dynamics. Recent experiments have demonstrated aging in biological systems that are inherently active with a magnitude of self-propulsion force f0 and a persistence time τp. Thus, what governs the aging dynamics in these active systems has fundamental importance. We formulate a generic mode-coupling theory (MCT) of active glasses to address this question in the regime when activity is not too large. The aging solutions of the theory show that the two-point correlation function decays more slowly with growing tw, and the relaxation time tr increases. The activity-modification of the MCT critical point, λC, has profound significance for active aging: the quench distance from λC governs aging and determines the aging exponent, δ, where tr ∼ tδw. δ decreases with increasing f0, in agreement with existing simulations. However, the variation with τp depends on the nature of activity. Our work has fundamental theoretical implications for active glasses and paves the way for a deeper understanding of the aging dynamics in biological systems.