  The results of a study of Dirac's Hamiltonian for a point electron in the
zero-gravity Kerr--Newman spacetime are reported; here, "zero-gravity" means G
to 0, where G is Newton's constant of universal gravitation, and the limit is
effected in the Boyer--Lindquist coordinate chart of the maximal analytically
extended, topologically nontrivial, Kerr--Newman spacetime. In a nutshell, the
results are: the essential self-adjointness of the Dirac Hamiltonian; the
reflection symmetry about zero of its spectrum; the location of the essential
spectrum, exhibiting a gap about zero; and (under two smallness assumptions on
some parameters) the existence of a point spectrum in this gap, corresponding
to bound states of Dirac's point electron in the electromagnetic field of the
zero-G Kerr--Newman ring singularity. The symmetry result of the spectrum
extends to Dirac's Hamiltonian for a point electron in a generalization of the
zero-G Kerr--Newman spacetime with different ratio of electric-monopole to
magnetic-dipole moment. The results are discussed in the context of the
general-relativistic Hydrogen problem. Also, some interesting projects for
further inquiry are listed in the last section.
