How to measure functional RG fixed-point functions for dynamics and at depinning

Abstract

We show how the renormalized force correlator Δ(u), the function computed in the functional RG (FRG) field theory, can be measured directly in numerics and experiments on the dynamics of elastic manifolds in the presence of pinning disorder. For equilibrium dynamics we recover the relation obtained recently in the statics between Δ(u) and a physical observable. Its extension to depinning reveals interesting relations to stick-slip models of avalanches used in dry friction and earthquake dynamics. The particle limit (d=0) is solved for illustration: Δ(u) exhibits a cusp and differs from the statics. We propose that the FRG functions be measured in wetting and magnetic interfaces experiments.