The NMSSM and string theory

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. (C) 2010 Elsevier B.V. All rights reserved.