Natural leptogenesis and neutrino masses with two Higgs doublets

TL;DR

This paper demonstrates that adding a second Higgs doublet to the minimal Type I see-saw model enables natural leptogenesis and neutrino mass explanations, predicting TeV-scale scalars and specific leptogenesis scales.

Contribution

It introduces a two-Higgs-doublet extension that overcomes naturalness issues in explaining neutrino masses and baryon asymmetry via hierarchical leptogenesis.

Findings

Models accommodate a SM-like Higgs boson

Predict TeV-scale scalar states

Enable low- to intermediate-scale hierarchical leptogenesis

Abstract

The minimal Type I see-saw model cannot explain the observed neutrino masses and the baryon asymmetry of the Universe via hierarchical thermal leptogenesis without ceding naturalness. We show that this conclusion can be avoided by adding a second Higgs doublet with $\tan\beta\gtrsim 4$. The models considered naturally accommodate a SM-like Higgs boson, and predict TeV-scale scalar states and low- to intermediate-scale hierarchical leptogenesis with $10^3\text{ GeV}\lesssim M_{N_1}\lesssim 10^8\text{ GeV}$.