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Teilchentee SS 2021
Date: 08.07.2021
Speaker: Gernot Eichmann
QCD contributions to the muon anomalous magnetic moment
The anomalous magnetic moment (g-2) of the muon continues to be one of the most promising places to look for evidence of new physics. First measurements at Fermilab have confirmed the previous Brookhaven result and slightly increased the tension with the Standard Model prediction to 4.2 standard deviations. The theoretical value is the sum of QED, electroweak and QCD contributions, where the hadronic parts are the most difficult to calculate and responsible for almost all of the theory uncertainty. The leading hadronic contribution is the hadronic vacuum polarization, whereas the hadronic light-by-light scattering contribution is much smaller but comes with a similar theoretical uncertainty. In this talk I will present an overview of the problem and the various approaches to compute the hadronic parts from dispersion theory, lattice QCD and Dyson-Schwinger calculations. I will focus in particular on the hadronic light-by-light contribution and discuss the different strategies in its computation.
