Formula omitted] conversion with four generations

Abstract

We study μ–e conversion with sequential four generations. A large mass for the fourth generation neutrino can enhance the conversion rate by orders of magnitude. We compare constraints obtained from μ–e conversion using experimental bounds on various nuclei with those from μ→eγ and μ→ee¯e. We find that the current bound from μ–e conversion with Au puts the most stringent constraint in this model. The relevant flavor changing parameter λμe=Vμ4⁎Ve4 is constrained to be less than 1.6×10−5 for the fourth generation neutrino mass larger than 100 GeV. Implications for future μ–e conversion, μ→eγ and μ→ee¯e experiments are discussed.