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

G. Abbiendi, C. Ainsley, P. F. Åkesson, G. Alexander, G. Anagnostou, K. J. Anderson, S. Asai, D. Axen, I. Bailey, E. Barberio, T. Barillari, R. J. Barlow, R. J. Batley, P. Bechtle, T. Behnke, K. W. Bell, P. J. Bell, G. Bella, A. Bellerive, G. BenelliS. Bethke, O. Biebel, O. Boeriu, P. Bock, M. Boutemeur, S. Braibant, R. M. Brown, H. J. Burckhart, S. Campana, P. Capiluppi, R. K. Carnegie, A. A. Carter, J. R. Carter, C. Y. Chang, D. G. Charlton, C. Ciocca, A. Csilling, M. Cuffiani, S. Dado, G. M. Dallavalle, A. de Roeck, E. A. de Wolf, K. Desch, B. Dienes, J. Dubbert, E. Duchovni, G. Duckeck, I. P. Duerdoth, E. Etzion, F. Fabbri, P. Ferrari, F. Fiedler, I. Fleck, M. Ford, A. Frey, P. Gagnon, J. W. Gary, C. Geich-Gimbel, G. Giacomelli, P. Giacomelli, R. Giacomelli, M. Giunta, J. Goldberg, E. Gross, J. Grunhaus, M. Gruwé, P. O. Günther, A. Gupta, C. Hajdu, M. Hamann, G. G. Hanson, A. Harel, M. Hauschild, C. M. Hawkes, R. Hawkings, R. J. Hemingway, G. Herten, R. D. Heuer, J. C. Hill, D. Horváth, P. Igo-Kemenes, K. Ishii, H. Jeremie, P. Jovanovic, T. R. Junk, J. Kanzaki, D. Karlen, K. Kawagoe, T. Kawamoto, R. K. Keeler, R. G. Kellogg, B. W. Kennedy, S. Kluth, T. Kobayashi, M. Kobel, S. Komamiya, T. Krämer, P. Krieger, J. von Krogh, T. Kuhl, M. Kupper, G. D. Lafferty, H. Landsman, D. Lanske, D. Lellouch, J. Letts, L. Levinson, J. Lillich, S. L. Lloyd, F. K. Loebinger, J. Lu, A. Ludwig, J. Ludwig, W. Mader, S. Marcellini, A. J. Martin, T. Mashimo, P. Mättig, J. McKenna, R. A. McPherson, F. Meijers, W. Menges, F. S. Merritt, H. Mes, N. Meyer, A. Michelini, S. Mihara, G. Mikenberg, D. J. Miller, W. Mohr, T. Mori, A. Mutter, K. Nagai, I. Nakamura, H. Nanjo, H. A. Neal, R. Nisius, S. W. O'Neale, A. Oh, M. J. Oreglia, S. Orito, C. Pahl, G. Pásztor, J. R. Pater, J. E. Pilcher, J. Pinfold, D. E. Plane, O. Pooth, M. Przybycień, A. Quadt, K. Rabbertz, C. Rembser, P. Renkel, J. M. Roney, A. M. Rossi, Y. Rozen, K. Runge, K. Sachs, T. Saeki, E. K.G. Sarkisyan, A. D. Schaile, O. Schaile, P. Scharff-Hansen, J. Schieck, T. Schörner-Sadenius, M. Schröder, M. Schumacher, R. Seuster, T. G. Shears, B. C. Shen, P. Sherwood, A. Skuja, A. M. Smith, R. Sobie, S. Söldner-Rembold, F. Spano, A. Stahl, D. Strom, R. Ströhmer, S. Tarem, M. Tasevsky, R. Teuscher, M. A. Thomson, E. Torrence, D. Toya, P. Tran, I. Trigger, Z. Trócsányi, E. Tsur, M. F. Turner-Watson, I. Ueda, B. Ujvári, C. F. Vollmer, P. Vannerem, R. Vértesi, M. Verzocchi, H. Voss, J. Vossebeld, C. P. Ward, D. R. Ward, P. M. Watkins, A. T. Watson, N. K. Watson, P. S. Wells, T. Wengler, N. Wermes, G. W. Wilson, J. A. Wilson, G. Wolf, T. R. Wyatt, S. Yamashita, D. Zer-Zion, L. Zivkovic

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28 Citations (Scopus)


Using the OPAL detector at LEP, the running of the effective QED coupling α(t) is measured for space-like momentum transfer from the angular distribution of small-angle Bhabha scattering. In an almost ideal QED framework, with very favourable experimental conditions, we obtain: Δα(-6.07 GeV2) - Δα(-1.81 GeV2) = (440 ± 58 ± 43 ± 30) × 10-5, where the first error is statistical, the second is the experimental systematic and the third is the theoretical uncertainty. This agrees with current evaluations of α(t). The null hypothesis that α remains constant within the above interval of -t is excluded with a significance above 5σ. Similarly, our results are inconsistent at the level of 3 σ with the hypothesis that only leptonic loops contribute to the running. This is currently the most significant direct measurement where the running α(t) is probed differentially within the measured t range.

Original languageEnglish
Pages (from-to)1-21
Number of pages21
JournalEuropean Physical Journal C
Issue number1
Publication statusPublished - 2006 Jan

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Physics and Astronomy (miscellaneous)

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