Study of the lepton-violating (μ-,e+) reaction in modern gauge theories

The lepton-violating (μ-, e+) reaction has been studied in the context of modern gauge theories. Both left-handed and right-left symmetric models have been examined. Special attention has been paid to the following mechanisms: (I) those mediated by massive neutrinos (light or heavy); (II) those accompanied by massless or light physical Higgs particles (majoron); (III) those involving more exotic intermediate Higgs particles, e.g. singly charged isosinglets (Zee model) and doubly charged isotriplets; (IV) right-handed currents. The formalism has been applied to the experimentally interesting process μ- + 58Ni -> 58Fe(gs) + e+. The branching ratio is computed using realistic nuclear wave functions. It is found to be < or approx. 10-27 in all models, i.e. too small to be measurable in the foreseeable future. The branching ratio for the (μ-, e+) reaction to all nuclear states is estimated to be < or approx. 10-20, i.e. beyond the goals of planned experiments. (orig.)