Eur. Phys. J. C 71, 1515 (2011)
https://doi.org/10.1140/epjc/s10052-010-1515-z

Reevaluation of the hadronic contributions to the muon g−2 and to α(M²_Z)

¹ Laboratoire de l’Accélérateur Linéaire, IN2P3/CNRS, Université Paris-Sud 11, Orsay, France
² CERN, 1211, Geneva 23, Switzerland

Andreas.Hoecker@cern.ch

Received: 21 October 2010
Revised: 26 November 2010
Published online: 5 January 2011

Abstract

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.