General types of Hamiltonians for particles of any spin

Abstract

An explicit determination is made of four general classes of Hamiltonians possible for particles of spins and massm as described by a Schrodinger equation invariant under Lorentz transformations and under T, C and P. Among these possibilities there is only one Hamiltonian which satisfies a regularity condition at the origin of momentum space; it has been considered earlier and found to be an adequate starting point for second quantizationonly in the half-integer spin case. This provides the motivation for explicit consideration of the other possibilities.