Creep via dynamical functional renormalization group

We study a D -dimensional interface driven in a disordered medium. We derive finite-temperature and velocity functional renormalization group (FRG) equations, valid in a = 4 − D expansion. These equations allow in principle for a complete study of the velocity v vs. applied force density f characteristics. We focus here on the creep regime at finite temperature and small velocity. We show how the FRG approach gives the form of the v - f characteristics in this regime, and in particular the creep exponent, obtained previously only through phenomenological scaling arguments.