Quantum mechanical equations of motion of particles and spin in polarized media

Abstract

Quantum mechanical equations of motion are obtained for particles and spin in media with polarized electrons in the presence of external fields. The motion of electrons and their spins is governed by the exchange interaction, while the motion of positrons and their spin is governed by the annihilation interaction. For particles with spin S ≥ 1, second-order terms in spin are taken into account. The equations obtained can be applied to describe the motion of particles and spin both in magnetic and nonmagnetic media.