Anomalous Energy Transport in the FPU-β Chain

We consider the energy current correlation function for the FPU-beta lattice. For small nonlinearity one can rely on kinetic theory. The issue reduces then to a spectral analysis of the linearized collision operator. We prove thereby that, on the basis of kinetic theory, the energy current correlations decay in time as t(-3/5). It follows that the thermal conductivity is anomalous, increasing as N-2/5 with the system size N. (c) 2008 Wiley Periodicals, Inc.