Abstract:The 2-Higgs-Doublet Model (2HDM) belongs to the simplest extensions of the Standard Model (SM) Higgs sector that are in accordance with theoretical and experimental constraints. In order to be able to properly investigate the experimental Higgs data and, in the long term to distinguish between possible models beyond the SM, precise predictions for the Higgs boson observables have to be made available on the theory side. This requires the inclusion of the higher order corrections. In this work, we investigate in detail the renormalization of the 2HDM, a pre-requisite for the computation of higher order corrections. We pay particular attention to the renormalization of the mixing angles α and β, which diagonalize the Higgs mass matrices and which enter all Higgs observables. The implications of various renormalization schemes in next-to-leading order corrections to the sample processes H ± → W ± h/H and H → ZZ are investigated. Based on our findings, we will present a renormalization scheme that is at the same time process independent, gauge independent and numerically stable.

The detailed investigation of the Higgs sector at present and future colliders necessitates from the theory side as precise predictions as possible, including higher order corrections. An important ingredient for the computation of higher order corrections is the renormalization of the model parameters and fields. In this paper we complete the renormalization of the 2-Higgs-Doublet Model (2HDM) Higgs sector launched in a previous contribution with the investigation of the renormalization of the mixing angles α and β. Here, we treat the renormalization of the mass parameter m 2 12 that softly breaks the Z 2 symmetry of the 2HDM Higgs sector. We investigate the impact of two different renormalization schemes on the sample Higgs-to-Higgs decay H → hh. This decay also allows us to analyze the renormalization of the mixing angles and to confirm the properties extracted before in other Higgs decays. In conclusion we find that a gauge-independent, process-independent and numerically stable renormalization of the 2HDM Higgs sector is given by the application of the tadpole-pinched scheme for the mixing angles α and β and by the use of the MS scheme for m 2

A consistent interpretation of the Higgs data requires the same precision in the Higgs boson masses and in the trilinear Higgs self-couplings, which are related through their common origin from the Higgs potential. In this work we provide the two-loop corrections at O(α t α s ) in the approximation of vanishing external momenta to the trilinear Higgs selfcouplings in the CP-violating Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM). In the top/stop sector two different renormalization schemes have been implemented, the OS and the DR scheme. The two-loop corrections to the self-couplings are of the order of 10% in the investigated scenarios. The theoretical error, estimated both from the variation of the renormalization scale and from the change of the top/stop sector renormalization scheme, has been shown to be reduced due to the inclusion of the two-loop corrections.

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