We determine numerically the parallel, perpendicular, and antisymmetric
diffusion coefficients for charged particles propagating in highly turbulent
magnetic fields, by means of extensive Monte Carlo simulations. We propose
simple expressions, given in terms of a small set of fitting parameters, to
account for the diffusion coefficients as functions of magnetic rigidity and
turbulence level, and corresponding to different kinds of turbulence spectra.
The results obtained satisfy scaling relations, which make them useful for
describing the cosmic ray origin and transport in a variety of different
astrophysical environments.Comment: 17 pages, 7 figure