Running of the Qed Coupling in Small-angle Bhabha Scattering at Lep
نویسنده
چکیده
Using the OPAL detector at LEP, the running of the effective QED coupling α(t) is measured for space-like momentum transfer, 2 ≤ −t ≤ 6 GeV, from the angular distribution of smallangle 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 α(t), based on data in the time-like region.
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