Reevaluation of the hadronic contributions to the muon g−2 and to α(M2Z)
Laboratoire de l’Accélérateur Linéaire, IN2P3/CNRS, Université Paris-Sud 11, Orsay, France
2 CERN, 1211, Geneva 23, Switzerland
Revised: 26 November 2010
Published online: 5 January 2011
We reevaluate the hadronic contributions to the muon magnetic anomaly, and to the running of the electromagnetic coupling constant at the Z-boson mass. We include new π + π − cross-section data from KLOE, all available multi-hadron data from BABAR, a reestimation of missing low-energy contributions using results on cross sections and process dynamics from BABAR, a reevaluation of all experimental contributions using the software package HVPTools together with a reanalysis of inter-experiment and inter-channel correlations, and a reevaluation of the continuum contributions from perturbative QCD at four loops. These improvements lead to a decrease in the hadronic contributions with respect to earlier evaluations. For the muon g−2 we find lowest-order hadronic contributions of (692.3±4.2)⋅10−10 and (701.5±4.7)⋅10−10 for the e + e −-based and τ-based analyses, respectively, and full Standard Model predictions that differ by 3.6σ and 2.4σ from the experimental value. For the e + e −-based five-quark hadronic contribution to we find . The reduced electromagnetic coupling strength at M Z leads to an increase by 12 GeV in the central value of the Higgs boson mass obtained by the standard Gfitter fit to electroweak precision data.
© Springer-Verlag / Società Italiana di Fisica, 2011