Seminarium Fizyki Wielkich Energii

The muon anomalous magnetic moment aμ=(g-2)/2 is a low-energy observable, which can be both measured and computed to high precision. The present experimental value corresponding to uncertainty of 0.54 ppm, comes from the BNL E821 experiment. This value deviates persistently from the SM prediction by about 3 standard deviations: (287+/-80) e-11. The discrepancy is not enough to claim the observation of new physics, but by far large enough to justify concerted international efforts to investigate this case with larger precision for both experiment and SM prediction. New measurements are planned within the next four years at Fermilab/USA and also at JPARC/Japan. The goal of the easurements is to reduce the uncertainty by a factor of four.In parallel the accuracy of the SM prediction is planned to be significantly improved. The part of the SM quantum corrections caused by hadrons is not easy to determine and entirely dominates the uncertainty of the SM prediction. A way out of this problem is provided by dispersion theory which links the hadronic quantum corrections for aμ to measurable hadronic properties. The hadronic vacuum polarization contribution (HVP) could be directly related to e+e− -> hadron processes. For the second part of hadronic contributionlight-by-light scattering (HLbL) recently an analogous strategy was proposed. The most important part of the HLbL contribution comes from the pseudoscalar pole terms which are in turn related to the transition form factors of pi0, eta and eta’ mesons.