Conformal Realization of the Neutrino Option

TL;DR

This paper explores a conformally invariant extension of the Standard Model that incorporates the neutrino option, where electroweak symmetry breaking and neutrino masses are generated dynamically through quantum effects and scale symmetry breaking.

Contribution

It identifies the minimal conformal model with two scalar singlets and right-handed neutrinos that realizes the neutrino option while maintaining perturbativity up to the Planck scale.

Findings

The model successfully generates a viable Higgs potential and neutrino masses.

Scale invariance breaking is driven by renormalization group effects.

The model remains perturbative up to the Planck scale.

Abstract

It was recently proposed that the electroweak hierarchy problem is absent if the generation of the Higgs potential stems exclusively from quantum effects of heavy right-handed neutrinos which can also generate active neutrino masses via the type-I seesaw mechanism. Hence, in this framework dubbed the "neutrino option", the tree-level scalar potential is assumed to vanish at high energies. Such a scenario therefore lends itself particularly well to be embedded in a classically scale-invariant theory. In this paper we perform a survey of models featuring conformal symmetry at the high scale. We find that the minimal framework compatible with the "neutrino option" requires the Standard Model to be extended by two real scalar singlet fields in addition to right-handed neutrinos. The spontaneous breaking of scale invariance, which induces the dynamical generation of Majorana masses for the right-handed neutrinos, is triggered by renormalization group effects. We identify the parameter space of the model for which a phenomenologically viable Higgs potential and neutrino masses are generated, and for which all coupling constants remain in the perturbative regime up to the Planck scale.