On Neutrino Masses and Mixings from Extra Dimensions

TL;DR

This paper explores how extra-dimensional theories can naturally generate small neutrino masses by coupling Standard Model singlet fermions in a higher-dimensional space, with implications for experimental bounds on fundamental scales.

Contribution

It introduces a mechanism for small neutrino masses within a Kaluza-Klein framework, analyzing constraints from pion decay data.

Findings

Bounds on the fundamental mass scale are potentially very stringent.

The model provides a natural explanation for small neutrino masses.

Numerical analysis supports the viability of the proposed mechanism.

Abstract

In the framework of a Kaluza-Klein type theory with the Standard Model fields localized on a 4-dimensional section while gravity propagates in a full $4+\delta$-dimensional space-time, we examine a mechanism of naturally small neutrino mass generation through couplings of Standard Model singlet fermion(s) living also in the full space-time. A numerical studies is carried out on the charged current universality constraint from the ratio of pion decay partial widths. The bounds obtained on the fundamental mass scale could be stringent.