Sterile Neutrino as a Bulk Neutrino

TL;DR

This paper proposes a novel higher-dimensional model where sterile neutrinos propagate in the bulk, naturally explaining their small mass without extra symmetries, and provides a realistic framework for neutrino masses and mixing.

Contribution

It introduces a new approach by identifying sterile neutrinos as bulk fermions in extra dimensions, addressing the small mass problem without additional symmetries.

Findings

A realistic model for neutrino masses and mixings

Small sterile neutrino mass explained by extra dimension size

No need for new symmetries to explain small mass

Abstract

If light sterile neutrinos are needed to understand the neutrino puzzles, as is currently indicated, a major theoretical challenge is to understand why its mass is so small. It is a more serious problem than understanding the small mass of the familiar neutrinos. We discuss a new way to solve this problem by identifying the sterile neutrino as gauge neutral fermion propagating in the bulk of a higher dimensional theory, with bulk size of order of a millimeter. The smallness of its mass is then a consequence of the size of the extra dimension and does not need the introduction of new symmetries. We present a realistic model for neutrino masses and mixings that implements this idea.