A kinematical interpretation of subsidiary conditions

Abstract

A linear relativistic wave equation is presumed to describe a particle with arbitrary spin. For the free particle with spin >1 the Klein-Gordon equation is a consequence of imposing subsidiary conditions on the solution of the linear equation. We use the correspondence principle to obtain the implied constraint on a classical spinning particle. The constraint is shown to be kinematically equivalent to the projection of a restricted class of particle motions. Further, the inconsistencies arising from minimal electromagnetic coupling are shown to correspond to an overconstraint of the particle multipole structure.