How the Inverse See-Saw Mechanism Can Reveal Itself Natural, Canonical and Independent of the Right-Handed Neutrino Mass

摘要

The common lore in the literature of neutrino mass generation is that thecanonical see-saw mechanism beautifully offers an explanation for the tinyneutrino mass but at the cost of introducing right-handed neutrinos at a scalethat is out of range for the current experiments. The inverse see-saw mechanismis an interesting alternative to the canonical one once it leads to tinyneutrino masses with the advantage of being testable at TeV scale. However,this last mechanism suffers from an issue of naturalness concerning the scaleresponsible for such small masses, namely, the parameter $\mu$ that is relatedto lepton number violation and is supposed to be at the keV scale, much lowerthan the electroweak one. However, no theoretical framework was built thatoffers an explanation for obtaining this specific scale. In this work wepropose a variation of the inverse see-saw mechanism by assuming a minimalscalar and fermionic set of singlet fields, along with a $Z_5\otimes Z_2$symmetry, that allows a dynamical explanation for the smallness of $\mu$,recovering the neat canonical see-saw formula and with right-handed (RH)neutrinos free to be at the electroweak scale, thus testable at LHC and currentneutrino experiments.