The Higgs Sector of the (Complex) NMSSM - Higher Order Corrections and Phenomenological Discussions

Abstract

We study the Higgs sector of the Next-to-Minimal Supersymmetric Standard Model. With seven physical Higgs bosons the NMSSM offers plenty of phenomenologically interesting possibilities. Especially in light of the recent discovery of a scalar resonance at 125~GeV at the LHC a discussion of these is highly relevant. However, in order to draw meaningful conclusions regarding the true nature of the Higgs sector the availability of higher order corrections to parameters and observables is essential. The rst part of this thesis presents the higher order corrections to the masses of the NMSSM Higgs bosons including the full one-loop contributions and two-loop contributions of the order O(st). The calculation is performed in the Feynman diagrammatic approach employing a renormalization scheme that mixes on-shell and DR conditions. The one-loop contributions are computed with full momentum dependence, whereas the two-loop corrections are calculated in the approximation of vanishing external momentum and in the gaugeless limit. The second part focuses on the discussion of scenarios compatible with the experimental observations of a Higgs boson at a mass of 125 GeV and the measured signal strengths. On the one hand we analyze the properties of the 125 GeV NMSSM Higgs boson and in what subspaces of the NMSSM parameter space it can be realized. On the other hand we investigate the discovery prospects of the other NMSSM Higgs bosons. We consider standard search channels, that were already applied in the search for the discovered Higgs boson, as well as channels which rely on decay chains involving Higgs-to-Higgs decays and which can lead to very exotic nal states.