ELECTROMAGNETIC DEFLECTION OF SPINNING PARTICLES

We show that it is possible to obtain self-consistent and physically a cceptable relativistic classical equations of motion for a pointlike s pin-half particle possessing an electric charge and a magnetic dipole moment, directly from a manifestly covariant Lagrangian, if the classi cal degrees of freedom are appropriately chosen. It is shown that the equations obtained encompass the well-tested Lorentz force and Thomas- Bargmann-Michel-Telegdi spin equations, as well as providing a definit e specification of the classical magnetic dipole force, whose exact fo rm has been the subject of recent debate. Radiation reaction - the for ce and torque on an accelerated particle due to its self-interaction - is neglected at this stage.