The evolution of the electromagnetic coupling, alpha, in the momentum-transfer range 1800 GeV(2) < -Q(2) < 21600 GeV(2) is studied with about 40 000 Bhabha-scattering events collected with the L3 detector at LEP at centre-of-mass energies root s = 189-209 GeV. The running of a is parametrised as: alpha(Q(2)) = (1-C Delta alpha(Q2))/(alpha 0) where alpha(0) = alpha(Q(2) = 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 vertical bar cos theta vertical bar < 0.9 excludes the hypothesis of a constant value of alpha, 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. (c) 2005 Elsevier B.V. All rights reserved.

Measurement of the running of the electromagnetic coupling at large momentum-transfer at LEP / P., A., O., A., M., A.B., J., A., G., A., J., A., A., A., M. G., A., H., A., V. P., A., F., A., A., A., T., A., T., A., Bagnaia, P., A., B., G., B., L., B., S. V., B., S., B., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 623:1-2(2005), pp. 26-36. [10.1016/j.physletb.2005.07.052]

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

BAGNAIA, Paolo;BORGIA, BRUNO;DIONISI, Carlo;GENTILE, Simonetta;GIAGU, Stefano;LONGO, Egidio;LUCI, Claudio;ORGANTINI, Giovanni;PARAMATTI, Riccardo;
2005

Abstract

The evolution of the electromagnetic coupling, alpha, in the momentum-transfer range 1800 GeV(2) < -Q(2) < 21600 GeV(2) is studied with about 40 000 Bhabha-scattering events collected with the L3 detector at LEP at centre-of-mass energies root s = 189-209 GeV. The running of a is parametrised as: alpha(Q(2)) = (1-C Delta alpha(Q2))/(alpha 0) where alpha(0) = alpha(Q(2) = 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 vertical bar cos theta vertical bar < 0.9 excludes the hypothesis of a constant value of alpha, 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. (c) 2005 Elsevier B.V. All rights reserved.
2005
01 Pubblicazione su rivista::01a Articolo in rivista
Measurement of the running of the electromagnetic coupling at large momentum-transfer at LEP / P., A., O., A., M., A.B., J., A., G., A., J., A., A., A., M. G., A., H., A., V. P., A., F., A., A., A., T., A., T., A., Bagnaia, P., A., B., G., B., L., B., S. V., B., S., B., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 623:1-2(2005), pp. 26-36. [10.1016/j.physletb.2005.07.052]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/361698
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