NEUTRINO SPIN KINETICS IN A MEDIUM WITH MAGNETIC-FIELD

The neutrino spin kinetic equation in a medium with a magnetic field i s derived, with the inclusion of the self-consistent electromagnetic f ield in a plasma. In order to check the proposed approach we reproduce the known results for the Dirac neutrino helicity change in constant and twisting magnetic fields. The new neutrino helicity change channel affected by the linear-polarized Alfven wave of a finite amplitude pr opagating along the general magnetic field Bo is considered. In contra st with the known cases, this channel arises for the longitudinal neut rino propagation p parallel to B-0, where p is the neutrino momentum.