Quantum-mechanical formulation of the electron-monopole interaction without Dirac strings

A relativistic wave equation is used to describe the interaction of an electron with a magnetic monopole at rest. A quasipotential, defined in terms of an integral involving the pseudoscalar potential phi/sub m/ = g/r, is used in this Dirac string-free formalism. This equation, written in nonrelativistic form, is used in conjunction with the appropriate angular momentum operators to obtain the Dirac quantization condition. An argument using gauge invariance shows that this condition is not modified by a relativistic treatment. A detailed comparison is made with conventional string theory, which is also formulated relativistically