A_4xSU(5) SUSY GUT of Flavour in 8d

TL;DR

This paper presents an 8-dimensional SU(5) SUSY GUT model with A_4 flavor symmetry, achieving vacuum alignment via orbifold boundary conditions, resulting in realistic fermion masses and mixing angles.

Contribution

It introduces a novel 8d SUSY GUT framework with orbifold boundary conditions for vacuum alignment, and incorporates A_4 symmetry to explain fermion flavor structure.

Findings

Realistic quark and lepton mass matrices achieved.

Tri-bimaximal neutrino mixing naturally emerges.

Model predicts inter-family mass hierarchies.

Abstract

We propose an SU(5) SUSY GUT of flavour with A_4 family symmetry in 8d where the vacuum alignment is achieved in an elegant way by the use of boundary conditions on orbifolds. The model involves SU(5) living in the 8d bulk, with matter living in 6d (or 4d) subspaces and Yukawa interactions occurring at a 4d point. The GUT group is broken to the Standard Model by the orbifold compactification, setting the GUT scale and leading to low energy supersymmetry and Higgs doublet-triplet splitting. The first two families of 10-plets are doubled resulting in a lack of both desirable and unwanted GUT relations. The resulting four dimensional effective superpotential leads to a realistic description of quark and lepton masses and mixing angles including tri-bimaximal neutrino mixing and an inter-family mass hierarchy provided in part by volume suppression and in part by a Froggatt-Nielsen mechanism.