Orientifolds, hypercharge embeddings and the Standard Model

TL;DR

This paper classifies hypercharge embeddings in orientifold models, constructing consistent vacua with realistic gauge groups and analyzing their properties, including supersymmetry and chiral matter content.

Contribution

It provides a systematic classification of hypercharge embeddings and constructs explicit orientifold vacua with realistic gauge groups and matter content.

Findings

Certain hypercharge embeddings are favored over others.

Configurations with chiral antisymmetric tensors are suppressed.

Examples of supersymmetric GUT models without chiral exotics are found.

Abstract

The embedding of the SM hypercharge into an orientifold gauge group is studied. Possible embeddings are classified, and a systematic construction of bottom-up configurations and top-down orientifold vacua is achieved, solving the tadpole conditions in the context of Gepner orientifolds. Some hypercharge embeddings are strongly preferred compared to others. Configurations with chiral antisymmetric tensors are suppressed. We find among others, genuine examples of supersymmetric SU(5), flipped SU(5), Pati-Salam and trinification vacua with no chiral exotics.