Spin phenomena in curved space-time with the metric in the Kerr–Schield form. Depolarization of the massive neutrino in the gravitational field

The solution of the Dirac equation in the wave package form in slightly curved space-time (compared with sizes of wave package) was studied. For the metric in the Kerr–Schield form a system of ordinary differential equations describing spin conditions of the massive neutral Dirac particles (neutrinos) was obtained. The effect of depolarization of the massive neutrinos in gravitational field was discussed.