Hadronic contribution to the running QED coupling at the Z-boson mass scale

Abstract

An update is described of a model independent method to determine the hadronic contribution to the QED running coupling at the Z-boson mass scale, $\Delta {\alpha }_{\text{HAD}}(M_Z^2)$. The major source of uncertainty is from the contribution of the light quark vector current correlator at zero momentum. This uncertainty is substantially reduced using recently improved lattice QCD results for this correlator. The result is $\Delta {\alpha }_{\text{HAD}}(M_Z^2)=274.13(0.73)\times 10^{-4}$.

arXiv comment5 pages, 1 figure, discussion extended