Predictions for g − 2 of the muon and αQED(M 2 Z)

Abstract

We calculate (g − 2) of the muon and the QED coupling α(M2 Z), by improving the determination of the hadronic vacuum polarization contributions and their uncertainties. We include the recently re-analysed CMD-2 data on e + e − → π + π −. We carefully combine a wide variety of data for the e + e − production of hadrons, and obtain the optimum form of R(s) ≡ σ0 had (s)/σpt(s), together with its uncertainty. Our results for the hadronic contributions to g − 2 of the muon are ahad,LO µ = (692.4 ± 5.9exp ± 2.4rad) × 10−10 and ahad,NLO µ = (−9.8 ± 0.1exp ± 0.0rad) × 10−10, and for the QED coupling ∆α (5) had (M2 Z) = (275.5±1.9exp ±1.3rad)×10 −4. These yield (g −2)/2 = 0.00116591763(74), which is about 2.4σ below the present world average measurement, and α(M2 Z)−1 = 128.954 ± 0.031. We compare our (g − 2) value with other predictions and, in particular, make a detailed comparison with the latest determination of (g − 2) by Davier et al.Contents 1