LONG-TAILED TRAPPING TIMES AND LEVY FLIGHTS IN A SELF-ORGANIZED CRITICAL GRANULAR SYSTEM

We present a continuous time random walk model for the scale-invariant transport found ill a self-organized critical rice pile [K. Christens en et al., Phys. Rev. Lett, 77, 107 (1996)]. From our analytical resul ts it is shown that the dynamics of the experiment can be explained in terms of Levy flights for the grains and a long-tailed distribution o f trapping times. Scaling relations for the exponents of these distrib utions are obtained. The predicted microscopic behavior is confirmed b y means of a cellular automaton model.