Scientific article
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Measurement of the running of the electromagnetic coupling at large momentum-transfer at LEP

ContributorsL3 Collaboration
Published inPhysics letters. B, vol. 623, no. 1-2, p. 26-36
Publication date2005
Abstract

The evolution of the electromagnetic coupling, α, in the momentum-transfer range 1800 GeV2<−Q2<21600 GeV2 is studied with about 40 000 Bhabha-scattering events collected with the L3 detector at LEP at centre-of-mass energies View the MathML sources=189–209 GeV. The running of α is parametrised as: α(Q2)=α01−CΔα(Q2), where α0≡α(Q2=0) is the fine-structure constant and C=1 corresponds to the evolution expected in QED. A fit to the differential cross section of the e+e−→e+e− process for scattering angles in the range |cosθ|<0.9 excludes the hypothesis of a constant value of α , C=0, and validates the QED prediction with the result: C=1.05±0.07±0.14, where the first uncertainty is statistical and the second systematic.

Citation (ISO format)
L3 Collaboration. Measurement of the running of the electromagnetic coupling at large momentum-transfer at LEP. In: Physics letters. B, 2005, vol. 623, n° 1-2, p. 26–36. doi: 10.1016/j.physletb.2005.07.052
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Journal ISSN0370-2693
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