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A theory driven analysis of the effective QED coupling at $M_Z$

J. H. Kühn·M. Steinhauser
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Abstract

An evaluation of the effective QED coupling at the scale M_Z is presented. It employs the predictions of perturbative QCD for the cross section of electron positron annihilation into hadrons up to order α_s^2, including the full quark mass dependence, and of order α_s^3 in the high energy region. This allows to predict the input for the dispersion relations over a large part of the integration region. The perturbative piece is combined with data for the lower energies and the heavy quark thresholds. The result for the hadronic contribution to the running of the coupling Δα^{(5)}_{\rm had}(M_Z^2)= (277.5 \pm 1.7)\times 10^{-4} leads to (α(M_Z^2))^{-1}=128.927 \pm 0.023. Compared to previous analyses the uncertainty is thus significantly reduced.

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J. H. Kühn, M. Steinhauser. 1998-07-21. A theory driven analysis of the effective QED coupling at $M_Z$. https://doi.org/10.1016/s0370-2693(98)00908-3

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