Hadronic Contributions to the Anomalous Magnetic Moment of the Muon

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The anomalous magnetic moment of the muon, αμ, is one of the most precisely determined observables of nature. Today, the experimental value and the theoretical number calculated within the standard model of particle physics disagree by roughly three standard deviations. This discrepancy may signal the exciting possibility of additional theoretical contributions from physics beyond the standard model. To corroborate this possibility it is of tremendous interest to further improve both, the experimental value for αμ and the theoretical prediction. In this project we aim at a significantly refined calculation of the theoretical value obtained within the standard model. Here, hadronic contributions governed by the strong interaction account for most of the uncertainties. In this project we plan to determine these contributions more precisely using a nonperturbative functional approach to the quantum field theory of strong interactions (QCD). The proposed method of Dyson-Schwinger and Bethe-Salpeter equations allows to go well beyond previous model calculations and thus has the potential for a refined calculation with considerably reduced error margins. If successful, our results will be a key element in the precise theoretical determination of αμ and thus provide an important ingredient for precision tests of physics beyond the standard model.