Search for Majorana neutrinos in $B^{-}\to \ddot{I}{€}^{+}\hat{I}{¼}^{-}\hat{I}{¼}^{-}$ decays

Abstract

A search for heavy Majorana neutrinos produced in the $B^{-}\to \ddot{I}{€}^{+}\hat{I}{¼}^{-}\hat{I}{¼}^{-}$ decay mode is performed using 3 fb${}^{-1}$ of integrated luminosity collected with the LHCb detector in $pp$ collisions at center-of-mass energies of 7 TeV and 8 TeV at the LHC. Neutrinos with masses in the range 250-5000 MeV and lifetimes from zero to 1000 ps are probed. In the absence of a signal, upper limits are set on the branching fraction $\mathcal{B}(B^{-}\to \ddot{I}{€}^{+}\hat{I}{¼}^{-}\hat{I}{¼}^{-})$ as functions of neutrino mass and lifetime. These limits are on the order of $10^{-9}$ for short neutrino lifetimes of 1 ps or less. Limits are also set on the coupling between the muon and a possible fourth-generation neutrino.

6 pages, 6 figures