How the inverse seesaw mechanism can reveal itself natural, canonical, and independent of the right-handed neutrino mass.

The common lore in the literature of neutrino mass generation is that the canonical seesaw mechanism beautifully offers an explanation for the tiny neutrino mass but at the cost of introducing right-handed neutrinos at a scale that is out of range for the current experiments. The inverse seesaw mechanism is an interesting alternative to the canonical one once it leads to tiny neutrino masses with the advantage of being testable at the TeV scale. However, this last mechanism suffers from an issue of naturalness concerning the scale responsible for such small masses, namely, the parameter μ that is related to lepton number violation and is supposed to be at the keV scale, much lower than the electroweak one. However, no theoretical framework was built that offers an explanation for obtaining this specific scale. In this work, we propose a variation of the inverse seesaw mechanism by assuming a minimal scalar and fermionic set of singlet fields, along with a Z5 ⊗ Z2 symmetry, that allows a dynamical explanation for the smallness of μ, recovering the neat canonical seesaw formula and with right-handed (RH) neutrinos tree to be at the electroweak scale, thus testable at LHC and current neutrino experiments. [ABSTRACT FROM AUTHOR]