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The q² running of effective QED coupling α(q²) is measured in a spacelike region, (10GeV)²≤-q²≤(54GeV)², using Bhabha-scattering and muon-pair production data at e⁺e^- collisions with a center-of-mass energy of 57.77 GeV. The result verifies the prediction of a theoretical estimation with a precision of better than 1% in terms of α(q²)/α(t₀) with t₀0ex0ex=0ex0ex-(10GeV)².
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Odaka et al. (1998) studied this question.
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