A comparison of the Higgs sectors of the CMSSM and NMSSM for a 126 GeV
  Higgs boson
  The recent discovery of a Higgs-like boson at the LHC with a mass of 126 GeV
has revived the interest in supersymmetric models, which predicted a Higgs
boson mass below 130 GeV long before its discovery. We compare systematically
the allowed parameter space in the constrained Minimal Supersymmetric Standard
Model (CMSSM) and the Next-to-Minimal Supersymmetric Model (NMSSM) by
minimizing the chi^2 function with respect to all known constraints from
accelerators and cosmology using GUT scale parameters. For the CMSSM the Higgs
boson mass at tree level is below the Z^0 boson mass and large radiative
corrections are needed to obtain a Higgs boson mass of 126 GeV, which requires
stop squark masses in the multi-TeV range. In contrast, for the NMSSM light
stop quarks are allowed, since in the NMSSM at tree level the Higgs boson mass
can be above the Z^0 boson mass from mixing with the additional singlet Higgs
boson. Predictions for the scalar boson masses are given in both models with
emphasis on the unique signatures of the NMSSM, where the heaviest scalar Higgs
boson decays in the two lighter scalar Higgs bosons with a significant
branching ratio, in which case one should observe double Higgs boson production
at the LHC. Such a signal is strongly suppressed in the CMSSM. In addition,
since the LSP is higgsino-like, Higgs boson decays into LSPs can be
appreciable, thus leading to invisible Higgs decays.
