Charged Higgs boson mass of the MSSM in the Feynman diagrammatic approach

The interpretation of the Higgs signal at $\sim$ 126 GeV within the Minimal Supersymmetric Standard Model (MSSM) depends crucially on the predicted properties of the other Higgs states of the model, as the mass of the charged Higgs boson, $M_{H^{\pm}}$. This mass is calculated in the Feynman-diagrammatic approach within the MSSM with real parameters. The result includes the complete one-loop contributions and the two-loop contributions of $O(\alpha_t\alpha_s)$. The one-loop contributions lead to sizable shifts in the $M_H^{\pm}$ prediction, reaching up to $\sim$ 8 GeV for relatively small values of M_A. Even larger effects can occur depending on the sign and size of the mu parameter that enters the corrections affecting the relation between the bottom-quark mass and the bottom Yukawa coupling. The two-loop $O(\alpha_t\alpha_s)$ terms can shift $M_H^{\pm}$ by more than 2 GeV. The two-loop contributions amount to typically about 30% of the one-loop corrections for the examples that we have studied. These effects can be relevant for precision analyses of the charged MSSM Higgs boson.