Exploring GeV-scale Majorana neutrinos in lepton-number-violating Λb0 baryon decays

In this work, the lepton-number-violating processes in |ΔL|=2 decays of Λb0 baryon, Λb0→pπ+μ-μ- and Λb0→Λc+π+μ-μ-, are investigated for the first time, via an intermediate on-shell Majorana neutrino N with a mass in the GeV scale. We explore the experimental sensitivity of these dimuon channels at the LHCb and CMS experiments, in which heavy neutrino lifetimes in the accessible ranges of τN=[1,100,1000] ps are considered. For a integrated luminosity collected of 10 and 50 fb-1 at the LHCb and 30, 300, and 3000 fb-1 at the CMS, we found significant sensitivity on branching fractions of the order BR(Λb0→pπ+μ-μ-)O(10-9-10-8) and BR(Λb0→Λc+π+μ-μ-)O(10-8-10-7). Exclusion regions on the parameter space (mN, |VμN|2) associated with the heavy neutrino are presented and compared with those from K-→π+μ-μ- (NA48/2) and B-→π+μ-μ- (LHCb) as well as by different search strategies such as NA3, CHARMII, NuTeV, Belle, and DELPHI.