Z-DEPENDENCE OF COHERENT MU-E CONVERSION RATE IN ANOMALOUS NEUTRINO-LESS MUON-CAPTURE

The coherent muon-electron conversion rate in anomalous neutrinoless muon capture by nuclei is calculated in terms of phenomenological coupling constants defined by effective Hamiltonian densities. The possibilities of muon-number violation occurring through lepton mixing, through muon-number-violating gauge couplings, or through scalar-Higgs-boson exchange are considered. The variation of the coherent conversion rate with atomic number Z is discussed for different values of the coupling constants. The present results are compared with a previous approximate formula given by Weinberg and Feinberg. The following limits on the phenomenological coupling constants are found: |gV(0)|<10-6 and |gV(1)|<2.9×10-4, or |gS(0)|<10-6 and |gS(1)|<3.2×10-4. © 1979 The American Physical Society.