Dirac neutrinos from a second Higgs doublet

TL;DR

This paper introduces a minimal extension to the Standard Model with a second Higgs doublet that naturally explains tiny Dirac neutrino masses, predicts observable lepton flavor violation, and offers distinctive collider signatures.

Contribution

It presents a novel model where a second Higgs doublet generates neutrino masses without tiny Yukawa couplings, enhancing naturalness and testability.

Findings

Predicts detectable mu to e gamma decay rates.

Suggests distinctive collider signatures of charged Higgs.

Excludes neutrinoless double beta decay.

Abstract

We propose a minimal extension of the Standard Model in which neutrinos are Dirac particles and their tiny masses are explained without requiring tiny Yukawa couplings. A second Higgs doublet with a tiny vacuum expectation value provides neutrino masses while simultaneously improving the naturalness of the model by allowing a heavier Standard Model-like Higgs boson consistent with electroweak precision data. The model predicts a mu to e gamma rate potentially detectable in the current round of experiments, as well as distinctive signatures in the production and decay of the charged Higgs H+ of the second doublet which can be tested at future colliders. Neutrinoless double beta decay is absent.