Hadronic part of the muon anomalous magnetic moment: An improved evaluation

We have done a new evaluation of the lowest-order hadronic vacuum-polarization contribution ${\mathit{a}}_{\mathrm{\mu }}^{\mathrm{vac}}$ to the anomalous magnetic moment of the muon. The result is ${\mathit{a}}_{\mathrm{\mu }}^{\mathrm{vac}}$=(7052±76)×${10}^{\mathrm{-}11}$ or ${\mathit{a}}_{\mathrm{\mu }}^{\mathrm{vac}}$=(7048±115)×${10}^{\mathrm{-}11}$ depending on the way in which the experimental systematic errors of the dominant two-pion contribution to ${\mathit{a}}_{\mathrm{\mu }}^{\mathrm{vac}}$ are taken into account. The more pessimistic error, though numerically equal to the earlier result of Casas, López, and Ynduráin, is still an improvement over the latter since it includes also the model error omitted in the previous analysis. The increased accuracy of ${\mathit{a}}_{\mathrm{\mu }}^{\mathrm{vac}}$ has been achieved through the use of global analytic models of the pion and kaon form factors for the two-pion and the two-kaon contributions as well as due to new experimental information mainly for the three-pion channel.