Uncertainties in the lightest C P even Higgs boson mass prediction in the minimal supersymmetric standard model: fixed order versus effective field theory prediction

We quantify and examine the uncertainties in predictions of the lightest CP even Higgs boson pole mass M-h in the Minimal Supersymmetric Standard Model (MSSM), utilising current spectrum generators and including some three-loop corrections. There are two broadly different approximations being used: effective field theory (EFT) where an effective Standard Model (SM) is used below a supersymmetric mass scale, and a fixed order calculation, where the MSSM is matched to QCDxQED at the electroweak scale. The uncertainties on the M-h prediction in each approach are broken down into logarithmic and finite pieces. The inferred values of the stop mass parameters are sensitively dependent upon the precision of the prediction for M-h. The fixed order calculation appears to be more accurate below a supersymmetry (SUSY) mass scale of M-S approximate to 1.2 TeV, whereas above this scale, the EFT calculation is more accurate. We also revisit the range of the lightest stop mass across fine-tuned parameter space that has an appropriate stable vacuum and is compatible with the lightest CP even Higgs boson h being identified with the one discovered at the ATLAS and CMS experiments in 2012; we achieve a maximum value of similar to 10(11) GeV.