(g  2)_{μ} and α(M^{2}_{Z}) reevaluated using new precise data
Abstract
We update our standard model predictions for g  2 of the muon and for the hadronic contributions to the running of the QED coupling, ∆α^{(5)}_{had}(M^{2}_{Z}). Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV. In particular, for the e^{+}e^{} → π^{+}π^{} contribution we include the recent 'radiative return' data from KLOE and BaBar. We also include the recent BaBar data on other exclusive channels. We make a detailed study of the effect of replacing the measurements of the inclusive cross section, σ(e^{+}e^{} → hadrons), by the sum of the exclusive channels in the energy interval 1.43 < \sqrt{s} < 2 GeV, which includes a QCD sumrule analysis of this energy region. Our favoured prediction for the muon anomalous magnetic moment is (g  2)/2 = (11 659 182.8 ± 4.9) × 10^{10} which is 3.3 σ below the present worldaverage measurement. We compare our g  2 value with other recent calculations. Our prediction for the QED coupling, obtained via ∆α^{(5)}_{had}(M_{Z}^{2}) = (276.26 ± 1.38) × 10^{4} , is α(M^{2}_{Z})^{1} = 128.944 ± 0.019.
 Publication:

Journal of Physics G Nuclear Physics
 Pub Date:
 August 2011
 DOI:
 10.1088/09543899/38/8/085003
 arXiv:
 arXiv:1105.3149
 Bibcode:
 2011JPhG...38h5003H
 Keywords:

 High Energy Physics  Phenomenology
 EPrint:
 30 pages, including 18 figures. Minor changes, published version