HET Seminar

Abstract: In order to fully exploit the accuracy of the experimental results obtained at the LHC experiments, also high precision on the theory side is required. Precise theoretical predictions need to be calculated including at least next-to-leading-order (NLO) electroweak corrections besides higher-order QCD contributions. In order to perform these higher-order calculations, a renormalization scheme has to be defined that specifies the relations between the parameters in the Lagrangian and the physical observables.

In this talk, I will focus on the treatment of vacuum expectation values, which is connected to the treatment of tadpole contributions and is particularly relevant if running masses or running mixing angles are used as input parameter both in the Standard Model and beyond. Depending on the chosen methods, problems such as gauge dependence or large unphysical higher-order contributions can occur. I will present two of the most commonly used treatments of the tadpole contributions, discuss the advantages and disadvantages and suggest a new scheme that combines the advantages of both of these commonly used treatments.