Monopole-induced proton disintegration

An effective Lagrangian is constructed for the interactions of fermions and monopoles. Canonical quantization is carried out, with special attention being paid to the meaning of gauge invariance and charge. This permits us to solve the mystery of the missing charge and demonstrate charge conservation in fermion-monopole scattering. A simple argument is presented for the screening of the electric field of the dyon (which is excited by the incoming fermion) with a consequent drastic reduction of the dyon-monopole mass difference. These results enable us to show that the basic reaction fermion + monopole→fermion′+dyon occurs at a sizable rate at low energies. Application is made to the SU(5) grand unified model. The explicit mechanism of baryon-number violation in such a reaction is seen to result from the interplay between the boundary conditions on the fermion fields and their occurrence in more than one SU(2) doublet.