Machta-Zwanzig regime of anomalous diffusion in infinite-horizon   billiards
  We study diffusion on a periodic billiard table with infinite horizon in the limit of narrow corridors. An effective trapping mechanism emerges according to which the process can be modeled by a L\'evy walk combining exponentially-distributed trapping times with free propagation along paths whose precise probabilities we compute. This description yields an approximation of the mean squared displacement of infinite-horizon billiards in terms of two transport coefficients which generalizes to this anomalous regime the Machta-Zwanzig approximation of normal diffusion in finite-horizon billiards [Phys. Rev. Lett. 50, 1959 (1983)]. 
Giampaolo Cristadoro, Thomas Gilbert, Marco Lenci and David P. Sanders
cond-mat.stat-mech math.DS nlin.CD