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

TL;DR

This paper proposes a variation of the inverse see-saw mechanism with a new symmetry that dynamically explains the small neutrino mass parameter, making the model testable at current collider and neutrino experiments.

Contribution

It introduces a minimal scalar and fermionic singlet field framework with a $Z_5 o Z_2$ symmetry to naturally generate the small neutrino mass scale in the inverse see-saw mechanism.

Findings

Dynamical explanation for the small $$ parameter.

Right-handed neutrinos can be at the electroweak scale.

Model testable at LHC and neutrino experiments.

Abstract

The common lore in the literature of neutrino mass generation is that the canonical see-saw 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 see-saw mechanism is an interesting alternative to the canonical one once it leads to tiny neutrino masses with the advantage of being testable at TeV scale. However, this last mechanism suffers from an issue of naturalness concerning the scale responsible for such small masses, namely, the parameter $\mu$ 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 see-saw mechanism by assuming a minimal scalar 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 current neutrino experiments.