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Running of the QED coupling in small-angle Bhabha scattering at LEP

G. Abbiendi
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Abstract

Using the OPAL detector at LEP, the running of the effective QED coupling alpha(t) is measured for space-like momentum transfer, 2 \leq -t \leq 6 GeV^2, from the angular distribution of small-angle Bhabha scattering. This is currently the most significant direct observation of the running of the QED coupling in a single experiment and the first clear evidence of the hadronic contribution to the running in the space-like region. Our result is in good agreement with standard evaluations of alpha(t), based on data in the time-like region.

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G. Abbiendi. 2005-05-18. Running of the QED coupling in small-angle Bhabha scattering at LEP. https://arxiv.org/abs/hep-ex/0505040

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