Low energy hadronic contribution to the QED vacuum polarization

Abstract
Recent improvements in the low energy e+e annihilation data and their influence on the determination of the hadronic contribution to the running of the QED fine structure constant at mZ are discussed. Using CMD-2 and KLOE measurements in the ρ region we obtain Δαhad(5)(s)=0.02758±0.00035 at s=mZ2.
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