Peter Drechsel (Deutsches Elektronen-Synchrotron (DESY))
The NMSSM represents an elegant and well motivated alternative description for the observed phenomenology in high energy physics. In this theory a scalar singlet together with its superpartner is added to the Higgs-sector of the Minimal Supersymmetric Standard Model (MSSM). In order to allow significant testing of the NMSSM by experiments precise predictions for the parameters of the theory are a necessity. The talk will focus on the prediction for the Higgs-masses in the NMSSM up to 2-loop order obtained by diagrammatic methods. While the calculation at 1-loop order is performed in the full NMSSM, the contributions at 2-loop order are taken from the MSSM as a very good approximation. The approximation will be motivated and its validity will be discussed in detail.