On the Causality Problem in Focused Particle Transport

Abstract When perpendicular diffusion is included into the focused transport equation, certain assumptions of coefficient (including well-known fieldline random walk limit) clearly lead to faster-than-light motion for relativistic particles, and that does not preserve causality in general. In this work we show discrepancy can be solved by including effect turbulence on particle drifts, especially streaming term present leading a so-called drift reduction factor. We discuss factor, how it solves above-mentioned problem, its general implications transport. Under simplifying interplay between (as process) diffusion, these processes consistently coupled through turbulent magnetic field.