On the Validity of Weak ParticleField Interaction Theory for the Description of CosmicRay Particle Diffusion in Random Magnetic Fields
Abstract
Since considerable debate has arisen recently about the applicability of the weakinteraction theory for the description of cosmicray particle diffusion in random magnetic fields, a critical discussion of the conditions of validity of this theory is presented. It is pointed out that the singular behaviour of the diffusion coefficient at pitch angles of θ=90° does not lead to a breakdown of the weakinteraction theory, though an extension of pitchangle scattering analysis to higher order may be necessary. In particular, an investigation of the δfunction contribution to the diffusion coefficient at pitch angles of 90° discovered by Fisket al. (1974) indicates that it has no influence on either pitchangle scattering or the associated problem of particle diffusion parallel to the mean magnetic field. Although an infinite diffusion coefficient at 90° pitch angles implies a singualr breakdown of the weakinteraction theory at that point, the effects are purely local and are negligible when considering averaged particle properties.
 Publication:

Astrophysics and Space Science
 Pub Date:
 October 1978
 DOI:
 10.1007/BF00644516
 Bibcode:
 1978Ap&SS..58..259A
 Keywords:

 Cosmic Rays;
 Interplanetary Magnetic Fields;
 Particle Diffusion;
 Weak Energy Interactions;
 Diffusion Coefficient;
 Field Theory (Physics);
 Particle Interactions;
 Random Processes;
 Theoretical Physics;
 Space Radiation