Order $\hbar$ Corrections to the Classical Dynamics of a Particle with Intrinsic Spin Moving in a Constant Magnetic Field

Abstract

$O(\hbar)$ effects that modify the classical orbit of a charged particle are described for the case of a classical spin-1/2 particle moving in a constant magnetic field, using a manifestly covariant formalism reported previously. It is found that the coupling between the momentum and spin gives rise to a shift in the cyclotron frequency, which is explicitly calculated. In addition the orbit is found to exhibit $O(\hbar)$ oscillations along the axis of the uniform static magnetic field whenever the gyromagnetic ratio $g$ of the particle is not 2. This oscillation is found to occur at a frequency $\propto$ $\frac{g}{2} - 1$, and is an observable source of electric dipole radiation.