We develop the quantum field theory of electron-point magnetic monopole interactions and, more generally, dyon-dyon interactions, based on the original string-dependent “nonlocal” action of Dirac and Schwinger. We demonstrate that a viable nonperturbative quantum field theoretic formulation can be constructed that results in a string independent cross section for monopole-electron and dyon-dyon scattering. Such calculations can be done only by using nonperturbative approximations such as the eikonal approximation and not by some mutilation of lowest-order perturbation theory.

• Received 28 October 1999

DOI:https://doi.org/10.1103/PhysRevD.61.075013