Equation of spin motion for a particle with electric and magnetic charges and dipole moments

Abstract

The general classical equation of spin motion is rigorously derived for a particle with electric and magnetic charges and dipole moments in electromagnetic fields. The equation describing the spin motion relative to the momentum direction in storage rings is also obtained. The importance of the derivation follows from a possible appearance of magnetic charges and EDMs due to the pseudoscalar \emph{CP}-violating electromagnetic interaction caused by dark matter axions.

Comments: 8 pages