# Majorana neutrino masses in gauge-Higgs unification

## TL;DR

This paper explores how small Majorana neutrino masses can naturally arise within the gauge-Higgs unification framework by proposing two models that incorporate different matter multiplets and mechanisms like seesaw and inverse seesaw.

## Contribution

It introduces two novel classes of models within gauge-Higgs unification that generate Majorana neutrino masses using different seesaw mechanisms.

## Key findings

- Neutrino masses are generated via a mixture of type-I and type-III seesaw in one model.
- Inverse seesaw mechanism successfully produces neutrino masses in the second model.
- Concrete models demonstrate the natural emergence of small neutrino masses in GHU.

## Abstract

The theory that the extra-space component of the gauge field is identified with the standard model Higgs boson, is called the gauge-Higgs unification (GHU) scenario. We examine how the small neutrino masses are naturally generated in the GHU framework. We find out two model classes where the following matter multiplets are introduced : 1. adjoint rep. lepton $\Psi_{A}$, 2. fundamental rep. lepton $\Psi_{F}$ and scalar $\Sigma_{F}$. We present a concrete model in each class. At the model in class 1, the neutrino masses are generated by the admixture of the seesaw mechanism type-I and -III. At the model in class 2, the masses are generated by the inverse seesaw mechanism.