Constraints on the Neutrino Extension of the Standard Model and Baryon Asymmetry of the Universe

Heavy neutral leptons (HNLs) can cause a new effective interactions of particles in the Standard Model, particularly charged lepton flavor violation (cLFV) processes. The non-observation of cLFV processes, therefore, puts constraints on the parameters of the HNLs. We find the relations between the cLFV effective operators in the realistic case where active neutrino masses are non-zero and masses of the HNLs are non-degenerate. This allows us to strengthen the existing cLFV constraints. We also link the baryon asymmetry of the Universe to the same cLFV effective operators, which imposes a new restrictions on their values.