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Electroweak renormalization based on gauge-invariant vacuum expectation values

We briefly review a recently proposed scheme for a gauge-invariant treatment of tadpole corrections in spontaneously broken gauge theories called Gauge-Invariant Vacuum expectation value Scheme (GIVS). The tadpole scheme matters in higher-order predictions of observables if not all free parameters are fixed by renormalization conditions based on S-matrix elements, such as in MSbar renormalization. In contrast to previously used tadpole schemes, the GIVS unifies the properties of gauge invariance and perturbative stability. The application of the GIVS to the Standard Model, for instance, leads to very moderate electroweak corrections in the conversion of on-shell-renormalized to MSbar-renormalized masses. Moreover, in models with extended Higgs sectors, the GIVS is less prone to perturbative instabilities in the MSbar renormalization of Higgs mixing angles than observed for the traditional gauge-independent tadpole treatment. We illustrate this by considering the next-to-leading-order (electroweak and QCD) corrections to the decay processes $h/H\to WW/ZZ\to4$fermions of the CP-even neutral Higgs bosons h and H in a singlet Higgs extension of the Standard Model and in the Two-Higgs-Doublet Model.