Fermion states on domain wall junctions and the flavor number

TL;DR

This paper investigates how fermion states can be localized on stable junctions of domain walls in higher-dimensional spacetime, exploring implications for the number of fermion flavors in a model inspired by Higgs physics.

Contribution

It introduces a model of intersecting domain walls in ten dimensions and analyzes fermion localization and flavor constraints at junctions, a novel approach to dimensional reduction.

Findings

Fermion zero modes and massive bound states are localized on domain walls.

Statistical preferences at junctions may constrain fermion flavor numbers.

The model provides insights into the mechanism of dimensional relaxation to three space dimensions.

Abstract

In this paper we address the problem of localizing fermion states on stable domain walls junctions. The study focus on the consequences of intersecting six independent 8d domain walls to form 4d junctions in a ten-dimensional spacetime. This is related to the mechanism of relaxing to three space dimensions through the formation of domain wall junctions. The model is based on six bulk real scalar fields, the phi-4 model in its broken phase, the prototype of the Higgs field, and is such that the fermion and scalar modes bound to the domain walls are the zero mode and a single massive bound state, which can be regarded as a two level system, at least at sufficiently low energy. Inside the junction, we use the fact that some states are statistically more favored to address the possibility of constraining the flavor number of the elementary fermions.