Quasi-Dirac Heavy Neutral Leptons in the Left-Right Symmetric Model

Abstract

We discuss the phenomenology of a pair of degenerate GeV-scale Heavy Neutral Leptons within the Left-Right Symmetric Model (LRSM) framework, with the third fermion serving as a dark matter candidate. We highlight the potential of the recently approved SHiP experiment to test the existence of the light DM species, and the signatures of lepton number violation as a possible experimental probe of the model in various experiments. Our findings include concrete predictions, in some part of the model's parameter space, for the effective right-handed couplings $(V_e^R{)}^2:(V_{\mu }^R{)}^2:(V_{\tau }^R{)}^2=0.16:0.47:0.38$ (normal neutrino hierarchy), $0.489:0.22:0.30$ (inverted hierarchy) of the degenerate pair.

Comments: 31 pages, 11 figures