CP violation with a GeV-scale Majorana neutrino in Λb→(Λc+,?p+)π+μ?μ? decays

摘要

We explore the possibility of C P violation in baryonic Λ b → ( Λ c + , p + ) π + μ ? μ ? decays which are mediated by two Majorana sterile neutrinos and are | Δ L | = 2 lepton-number-violating processes. Appreciable C P asymmetry can be obtained if there are two on-shell Majorana neutrinos that are quasidegenerate in mass with the mass difference of the order of average decay widths. We find that, given the present constraints on the heavy to light mixing element | V μ N | , the Λ b → p + π + μ ? μ ? and Λ b → Λ c + π + μ ? μ ? decay rates are suppressed but could be within the experimental reach at the LHC. If searches of the modes are performed, then experimental limits on the rates can be translated to constraints on the Majorana neutrino mass m N and heavy to light mixing element squared | V μ N | 2 . We show that the constraints on the ( m N , | V μ N | 2 ) parameter space coming from the | Δ L | = 2 baryonic decays are complementary to the bounds coming from other processes.