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Résumé |
In view of increasingly precise measurements of observables in Higgs physics, equally precise theory
predictions are required in order to distinguish models that correctly describe nature.
In supersymmetric extensions of the Standard Model higher-order corrections to Higgs-boson masses or
decay widths can be sizable. The most important corrections are typically of QCD type, but after the
advances in recent years also electroweak corrections become important. However, some parameters of the
extended Higgs sector are related to the gauge sector and not free parameters due to supersymmetry. As a
consequence not all Higgs fields can be renormalised on-shell and therefore mix among one another. Since
this mixing is scheme and gauge dependent, the fate of electroweak loop corrections is a priori unclear.
At the example of the (N)MSSM, I will compare the strict perturbative expansion and the Z-matrix
formalism for the description of Higgs mixing at higher order. I will address the cancellation of unphysical
degrees of freedom in Higgs decay widths at the analytical level and also show its relevance at the
numerical level. Finally, I will illustrate some limitations of the derived methods in scenarios with light
singlet-dominated Higgs states and propose different possible solutions. |
