SUBDIFFUSIVE TRANSPORT IN STOCHASTIC WEBS

We study a one-parameter family of piecewise linear, continuous area preserving maps of the plane. At an infinite discrete set of parameter values the phase space is globally connected. The transport proceeds in stochastic webs which are structurally similar to those described recently by Zaslavsky and coworkers. However the transport is subdiffusive, i.e. the energy grows with time as t-alpha, where alpha < 1. This behavior is explained in terms of a Markov model derived from a detailed analysis of the phase space structure, and it is shown that alpha = 2/3 asymptotically. For a special case we identify sublattices in phase space which show nongeneric transport with alpha = 1.