Search for heavy neutrinos in K+→μ+νμ decays

NA62 Collaboration (2017) Search for heavy neutrinos in K+→μ+νμ decays. Physics Letters B, 772 (Supple). pp. 712-718. ISSN 0370-2693

Abstract

The NA62 experiment recorded a large sample of K+→μ+νμ decays in 2007. A peak search has been performed in the reconstructed missing mass spectrum. In the absence of a signal, limits in the range 2×10−6 to 10−5 have been set on the squared mixing matrix element |Uμ4|2 between muon and heavy neutrino states, for heavy neutrino masses in the range 300–375 MeV/c2. The result extends the range of masses for which upper limits have been set on the value of |Uμ4|2 in previous production search experiments.