Neutrino mass from neutrinophilic Higgs and leptogenesis

TL;DR

This paper explores a two Higgs doublet model where a tiny second Higgs VEV explains neutrino masses and enables low-scale thermal leptogenesis, addressing key issues in neutrino physics and cosmology.

Contribution

It introduces a model with a small second Higgs VEV that naturally accounts for neutrino masses and allows low-energy scale leptogenesis with reduced degeneracy requirements.

Findings

Lightest right-handed neutrino can be as light as 100 TeV.

Degeneracy for resonant leptogenesis can be as low as 10^4.

Provides a solution to the gravitino problem in supergravity.

Abstract

In a class of two Higgs doublet model, where one Higgs doublet generates masses of quarks and charged leptons whereas the other Higgs doublet with a tiny vacuum expectation value (VEV) generates neutrino Dirac masses, smallness of neutrino masses might be understand as the consequence of the small second Higgs VEV. In this framework, thermal leptogenesis scenarios work well at low energy scale and have several advantages as follows. Under the assumption of hierarchical right-handed neutrino masses, the lightest right-handed neutrino can be as light as ${\cal O}(10^2)$ TeV.The required degeneracy for successful resonant leptogenesis also can be significantly reduced as small as ${\cal O}(10^4)$. Availability of low scale thermal leptogenesis provides a novel solution to gravitino problem in supergravity models.