Lepton-number violation in Bs meson decays induced by an on-shell Majorana neutrino

Lepton-number violation can be induced by the exchange of an on-shell Majorana neutrino N in semileptonic |ΔL|=2 decays of the Bs meson, Bs0→P-π-μ+μ+ with P=K,Ds. We investigate the production of such a heavy sterile neutrino through these four-body μ+μ+ channels and explore the sensitivity that can be reached at the LHCb and CMS experiments. For heavy neutrino lifetimes of τN=[1,100,1000] ps and integrated luminosities collected of 10 and 50 fb-1 at the LHCb and 30, 300, and 3000 fb-1 at the CMS, we find a significant sensitivity on branching fractions of the orders BR(Bs0→K-π-μ+μ+) O(10-9-10-8) and BR(Bs0→Ds-π-μ+μ+) O(10-8-10-7). In the kinematically allowed mass ranges of mN[0.25,4.77] GeV and mN[0.25,3.29] GeV, respectively, we exclude regions on the parameter space (mN,|VμN|2) associated with the heavy neutrino, which could slightly improve the limits from B-→π+μ-μ- (LHCb).