Cosmological domain walls from the breaking of $\mathbf{S_4}$ flavor symmetry

Abstract

In this work, we delve into the often-overlooked cosmological implications of spontaneous breaking of non-Abelian discrete groups, specifically focusing on the formation of domain walls in the case of $S_{4}$ flavor symmetry. In particular, we investigate three interesting breaking patterns of the $S_4$ group and study the structure of the domain walls in the broken phase for three possible residual symmetries. The presentation of domain walls in the case of multiple vacua is usually complicated, which therefore implies that most of the analyzes only approximate their presentation. Here, we propose a subtle way to represent the $S_{4}$ domain wall networks by presenting the vacua in each breaking pattern as vectors with their components corresponding to their coordinates in the flavon space. Then, through the properties of the obtained vectors, we find that the domain wall networks can be represented by Platonic or Archimedean solids where the vertices represent the degenerate vacua while the edges correspond to the domain walls that separate them. As an illustration, we propose a type-II seesaw model that is based on the $S_{4}$ flavor symmetry, and study its phenomenological implications on the neutrino sector. To solve the domain wall problem within this toy model, we consider an approach based on high-dimensional effective operators induced by gravity that explicitly break the structure of the induced vacua favoring one vacuum over the others.