A Model of electroweak-scale right-handed neutrino mass

Abstract If neutrino masses are realized through the see-saw mechanism, can the right-handed neutrinos be produced and detected at present and future colliders? The answer is negative in the most popular see-saw scenarios for the simple reason that they are too heavy in these models. However, a simple extension of the Standard Model (SM) particle content, including mirror fermions, two SU ( 2 ) L triplet and one singlet Higgs fields, leads to a scenario in which the see-saw mechanism is realized with the Majorana mass M R of the right-handed neutrino being of the order of the electroweak scale or smaller. A custodial SU ( 2 ) symmetry arising from the two triplet Higgs fields ensures that ρ = 1 at tree level even when their vacuum expectation values (VEV) which determine the value of M R , can be as large as the electroweak scale. M R is found to obey the bound M Z 2 ⩽ M R 246 GeV which makes it accessible experimentally (Tevatron, LHC or ILC) since, in our scenario, ν R 's can couple directly to the Standard Model (SM) gauge bosons.