Exploring the Higgs sector of a most natural NMSSM

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The Next to Minimal Supersymmetric Standard Model (NMSSM) with a Higgs-singlet coupling λ close to unity, moderate tan β and stop masses below 1 TeV minimizes the fine tuning of the electroweak scale, making possible that the lightest new particles, except perhaps for the LSP, be part of the extended Higgs system. We show how the measurements of the couplings of the 126 GeV Higgs boson constrain the region of the physical parameters of a generic NMSSM most relevant to this context. In the same region of parameter space we determine the cross section for the production of a heavier CP-even scalar together with its total width and its most relevant branching ratios. For comparison we show the same analysis for the MSSM. We also comment on how a coupling λ 1 can be compatible with gauge coupling unification.