Searches for Majorana neutrinos in B ^- decays

Searches for heavy Majorana neutrinos in B ^- decays in final states containing hadrons plus a μ ^-μ ^- pair have been performed using 0.41fb ^-1 of data collected with the LHCb detector in proton-proton collisions at a center-of-mass energy of 7 TeV. The D ⁺μ ^-μ ^- and D ^{* +}μ ^-μ ^- final states can arise from the presence of virtual Majorana neutrinos of any mass. Other final states containing π ⁺, Ds+, or D0π ⁺ can be mediated by an on-shell Majorana neutrino. No signals are found and upper limits are set on Majorana neutrino production as a function of mass, and also on the B ^- decay branching fractions.