I will talk about the current status of the Standard Model (SM) prediction for the muon g-2. Currently, there is more than 3.5 sigma discrepancy between the experimental value of the muon g-2 and the SM prediction for it. In the SM prediction, the hadronic contribution is the largest source of the uncertainty. The leading-order (LO) hadronic contribution, which is one of the most uncertain contributions among the hadronic contributions, can be evaluated by using the experimental data of e+ e- --> hadrons as input. Thanks to the recent precise data on e+ e- --> pi+ pi- and the improved theoretical method to combine data, the precision of the prediction for the LO hadronic contribution has now been reduced to the level of 0.4 %. I will give an overview of these situations.
|Working Group||WG4 : Muon Physics|