Neutrino masses and mixing from S4 flavor twisting

TL;DR

This paper presents a neutrino mass model utilizing S4 symmetry with boundary condition-induced symmetry breaking in a five-dimensional framework, linking neutrino mixing patterns to extra-dimensional parameters and testable predictions.

Contribution

It introduces a novel S4 flavor symmetry model with boundary condition breaking in extra dimensions, connecting neutrino mass hierarchies to geometric parameters.

Findings

Reactor angle magnitude relates to neutrino mass hierarchy.

Normal hierarchy favored by early reactor angle discovery.

Inverted hierarchy favored by late reactor angle discovery.

Abstract

We discuss a neutrino mass model based on the S4 discrete symmetry where the symmetry breaking is triggered by the boundary conditions of the bulk right-handed neutrino in the fifth spacial dimension. While the symmetry restricts bare mass parameters to flavor-diagonal forms, the viable mixing angles emerge from the wave functions of the Kaluza-Klein modes which carry symmetry breaking effect. The magnitudes of the lepton mixing angles, especially the reactor angle is related to the neutrino mass patterns and the model will be tested in future neutrino experiments, e.g., an early (late) discovery of the reactor angle favors the normal (inverted) hierarchy. The size of extra dimension has a connection to the possible mass spectrum; a small (large) volume corresponds to the normal (inverted) mass hierarchy.