Radiative decay of the fermionic state with vanishing angular momentum in the field of a magnetic monopole

As one of the possible mechanisms which may reduce the rate for the monopole-catalyzed proton decay, the radiative transition of the fermionic state with vanishing angular momentum (J) into those with higher J is investigated. The lowest-order formula for the transition rate, which nevertheless takes full account of the interaction with the background monopole field, is derived and numerically evaluated. It is found that the decay rate for a light fermion is unusually large. (e.g. one photon emission rate for a positron, with an incident energy of 300 MeV, is about 30 MeV). Our results indicate that by itself the one gauge boson emission rate is not expected to affect the catalysis substantially, but that it is large enough to call for further study of multiple emissions and higher-order corrections. (orig.)