A3b: Precision predictions for Higgs boson properties as a probe for New Physics

In project A3b we perform precision calculations related to the Higgs boson mass in supersymmetric extensions of the Standard Model and to the Higgs boson self-couplings. QCD and electroweak corrections to Higgs boson pair production are computed both numerically and analytically. Further information about the Higgs self-couplings are obtained from Higgs-to-Higgs decays which are considered in various extensions of the Standard Model.

1. Higgs Boson Pair Production: Higher order corrections to Standard Model pair production up to N$^3$LO in QCD and NLO in the electroweak sector.
2. NLO corrections including the full mass dependences of all loop particles in the Standard Model and in the MSSM for neutral Higgs pairs, $gg \to hh, HH, hH,AA$, if time permits also $hA, HA$.
3. Higgs-to-Higgs Decay: electroweak corrections in the CP-violating Two-Higgs-Doublet Model (C2HDM) and the next-minimal supersymmetric model (NMSSM); comparative analysis of Higgs to Higgs decays in the Next-Minimal 2HDM (N2HDM), C2HDM and NMSSM; all models allow for sequences of Higgs-to-Higgs decays.
4. Higgs Boson Mass in the MSSM and NMSSM: Higgs Boson Mass in the MSSM and NMSSM; three-loop corrections of order $\alpha_b \alpha_s^2$ ; $\alpha_{t,b}^2 \alpha_s$, $\alpha_{t,b}^3$ to MSSM Higgs masses; two-loop corrections to NMSSM Higgs masses in different renormalization schemes, including singlet coupling $\lambda$, $\kappa$ contributions: order $\alpha_t \alpha_\lambda$, $\alpha_\lambda^2$, $(\alpha_t + \alpha_\kappa)^2$.