paper

Langevin equations for continuous time Lévy flights

arXiv:cond-mat/9402042 · doi:10.1103/PhysRevE.50.1657

Abstract

We consider the combined effects of a power law Lévy step distribution characterized by the step index and a power law waiting time distribution characterized by the time index on the long time behavior of a random walker. The main point of our analysis is a formulation in terms of coupled Langevin equations which allows in a natural way for the inclusion of external force fields. In the anomalous case for and the dynamic exponent locks onto the ratio . Drawing on recent results on Lévy flights in the presence of a random force field we also find that this result is {\em independent} of the presence of weak quenched disorder. For below the critical dimension the disorder is {\em relevant}, corresponding to a non trivial fixed point for the force correlation function.

10 pages, Latex, IFA Report No. 94/10

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