The NMSSM and String Theory

TL;DR

This paper explores the construction of the NMSSM from heterotic string theory, highlighting the rarity of such models and their characteristic features like suppressed singlet self-interactions and potential solutions to fine-tuning issues.

Contribution

It provides a specific heterotic orbifold example of the NMSSM with approximate Peccei-Quinn symmetry derived from string selection rules and vacuum configurations.

Findings

String-derived NMSSMs are rare compared to MSSMs.

The spectrum often includes a light pseudoscalar relevant to fine-tuning.

An explicit Z_6 heterotic orbifold example is presented.

Abstract

We study the possibility of constructing the NMSSM from the heterotic string. String derived NMSSMs are much more rare than MSSMs due to the extra requirement that there exist a light singlet which couples to the Higgs pairs. They share the common feature that the singlet self-interactions are typically suppressed, leading to either the "decoupling" or the Peccei-Quinn limit of the NMSSM. In the latter case, the spectrum contains a light pseudoscalar which may be relevant to the MSSM fine-tuning problem. We provide a Z_6 heterotic orbifold example of the NMSSM with approximate Peccei-Quinn symmetry, whose origin lies in the string selection rules combined with our choice of the vacuum configuration.