Next-to-leading order prediction for the decay mu to ekern0.22em left({e}^{+}{e}^{-}right);nu kern0.2em overline{nu}

Abstract

We present the differential decay rates and the branching ratios of the muon decay with internal conversion, mu to ekern0.22em left({e}^{+}{e}^{-}right);nu kern0.2em overline{nu} , in the Standard Model at next-to-leading order (NLO) in the on-shell scheme. This rare decay mode of the muon is among the main sources of background to the search for μ → eee decay. We found that in the phase space region where the neutrino energies are small, and the three-electron momenta have a similar signature as in the μ → eee decay, the NLO corrections decrease the leading-order prediction by about 10 − 20% depending on the applied cut.