Exotic μ−→e− conversion in nuclei: energy moments of the transition strength and average energy of the outgoing e− Original Research Article

The first-order and zero-order energy-weighted moments of the transition strength in the inclusive μ−→e− conversion process are investigated with explicit term-by-term calculations. The required full set of intermediate states is deduced within the renormalized quasiparticle random phase approximation which considers reliably the nucleon–nucleon ground-state correlations. The results are exploited to study the average energy of the outgoing electron in the process and subsequently to test the validity of the closure approximation employed previously in inclusive μ−→e− studies. We focus our attention on the particularly interesting nuclei 48Ti and 208Pb, i.e. the stopping targets of the ongoing SINDRUM II experiments. Our conclusions are discussed in conjunction with other similar processes, like the allowed ordinary muon capture and the exotic μ−→e+ conversion.