Supersymmetric Standard Model from the Heterotic String (II)

TL;DR

This paper presents a detailed heterotic string compactification that yields a supersymmetric standard model with realistic features, including gauge coupling unification and natural Yukawa coupling hierarchies.

Contribution

It constructs a Z_6 orbifold heterotic string model that reproduces the MSSM gauge group and matter content with realistic phenomenology.

Findings

Realistic MSSM gauge group and matter content achieved

Supersymmetry preserved without exotics at low energies

Yukawa couplings exhibit hierarchical structure

Abstract

We desribe in detail a Z_6 orbifold compactification of the heterotic E_8 x E_8 string which leads to the (supersymmetric) standard model gauge group and matter content. The quarks and leptons appear as three 16-plets of SO(10), two of which are localized at fixed points with local SO(10) symmetry. The model has supersymmetric vacua without exotics at low energies and is consistent with gauge coupling unification. Supersymmetry can be broken via gaugino condensation in the hidden sector. The model has large vacuum degeneracy. Certain vacua with approximate B-L symmetry have attractive phenomenological features. The top quark Yukawa coupling arises from gauge interactions and is of the order of the gauge couplings. The other Yukawa couplings are suppressed by powers of standard model singlet fields, similarly to the Froggatt-Nielsen mechanism.