Spin invariants and uniqueness of spin operators

The problem of uniqueness of spin operators for Dirac particles is examined. To this end, invariant spin relations based on the spin projection in the rest frame are constructed. Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 7–11, 1999.     

Semiclassical Correspondence Principle for Charge Motion and Spin Precession in a Homogeneous Magnetic Field

Solutions to the classical equation of charge motion and the Bargmann–Michel–Telegdi spin equation are derived within a semiclassical approximation (for high energy levels) using the associated solutions to the Dirac–Pauli equation.