Chandrasekhar separation ansatz and the generalized total angular momentum for the Dirac equation in the Kerr-Newman metric.

In this paper we compute the square root of the generalized squared total angular momentum operator J for a Dirac particle in the Kerr-Newman metric. The separation constantarising from the Chandrasekahr separation ansatz turns out to be the eigenvalue of J. After proving that J is a symmetry operator, we show the completeness of Chandrasekhar ansatz for the Dirac equation in oblate spheroidal coordinates and derive an explicit formula for the propagator e itH .