The motion of energetic particles in magnetic turbulence across a mean
magnetic field is explored analytically. The approach presented here allows for
a full time-dependent description of the transport, including compound
sub-diffusion. The first time it is shown systematically that as soon as there
is transverse structure of the turbulence, diffusion is restored even if no
Coulomb collisions are invoked. Criteria for sub-diffusion and normal Markovian
diffusion are found as well.Comment: Paper was accepted by Physics of Plasmas Letters on April 18th, 201