Bound states of a fermion-dyon system

Abstract

The bound states of fermions in the external field of an Abelian dyon are studied here both analytically and numerically. Their existence is due to the dyon's electric charge resulting from a polarization of the fermionic vacuum. The configuration of the dyon's field is not invariant under $P$ or $CP$ transformations. The dependence of the energy levels of the fermion-dyon system on a parameter of $CP$ violation is investigated. The absence of $P$ invariance results in nonzero electric dipole moments of the bound fermionic states. These depend nontrivially on the parameter of $CP$ violation. The bound fermionic states also possess nonzero magnetic dipole moments. Unlike the electric dipole moments, the magnetic dipole moments are practically independent of the parameter of $CP$ violation. In addition, the magnitudes of the electric dipole moments significantly exceed those of the magnetic dipole moments.