Volume 77, Number 6, March 2007
Article Number 66001
Number of page(s) 5
Section Condensed Matter: Structural, Mechanical and Thermal Properties
Published online 02 March 2007
EPL, 77 (2007) 66001
DOI: 10.1209/0295-5075/77/66001

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

P. Le Doussal and K. J. Wiese

CNRS-Laboratoire de Physique Théorique de l'Ecole Normale Supérieure - 24 rue Lhomond, 75231 Paris Cedex, France and KITP, UCSB - Santa Barbara, CA 93106-4030, USA

received 19 October 2006; accepted in final form 25 January 2007; published March 2007
published online 2 March 2007

We show how the renormalized force correlator $\Delta (u)$, 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 $\Delta (u)$ 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: $\Delta (u)$ exhibits a cusp and differs from the statics. We propose that the FRG functions be measured in wetting and magnetic interfaces experiments.

64.60.Ak - Renormalization-group, fractal, and percolation studies of phase transitions .

© Europhysics Letters Association 2007