Measurement of the cross sections of the reactions e+e- → γγ and e+e- → γγγ at LEP

M. Z. Akwawy*, G. Alexander, J. Allison, P. P. Allport, K. J. Anderson, J. C. Armitage, G. T.J. Arnison, P. Ashton, G. Azuelos, J. T.M. Baines, A. H. Ball, J. Banks, G. J. Barker, R. J. Barlow, J. R. Batley, G. Beaudoin, A. Beck, J. Becker, T. Behnke, K. W. BellG. Bella, S. Bethke, O. Biebel, U. Binder, I. J. Bloodworth, P. Bock, H. Breuker, R. M. Brown, R. Brun, A. Buijs, H. J. Burckhart, P. Capiluppi, R. K. Carnegie, A. A. Carter, J. R. Carter, C. Y. Chang, D. G. Charlton, J. T.M. Chrin, P. E.L. Clarke, I. Cohen, W. J. Collins, J. E. Conboy, M. Couch, M. Coupland, M. Cuffiani, S. Dado, G. M. Dallavalle, S. De Jong, P. Debu, M. M. Deninno, A. Dieckmann, M. Dittmar, M. S. Dixit, E. Duchovni, I. P. Duerdoth, D. J.P. Dumas, P. A. Elcombe, P. G. Estabrooks, E. Etzion, F. Fabbri, P. Farthouat, H. M. Fischer, D. G. Fong, M. T. French, C. Fukunaga, A. Gaidot, O. Ganel, J. W. Gary, J. Gascon, N. I. Geddes, C. N.P. Gee, C. Geich-Gimbel, S. W. Gensler, F. X. Gentit, G. Giacomelli, V. Gibson, W. R. Gibson, J. D. Gillies, J. Goldberg, M. J. Goodrick, W. Gorn, D. Granite, E. Gross, J. Grunhaus, H. Hagedorn, J. Hagemann, M. Hansroul, C. K. Hargrove, I. Harrus, J. Hart, P. M. Hattersley, M. Hauschild, C. M. Hawkes, E. Heflin, R. J. Hemingway, R. D. Heuer, J. C. Hill, S. J. Hillier, D. A. Hinshaw, C. Ho, J. D. Hobbs, P. R. Hobson, D. Hochman, B. Holl, R. J. Homer, S. R. Hou, C. P. Howarth, R. E. Hughes-Jones, R. Humbert, P. Igo-Kemenes, H. Ihssen, D. C. Imrie, L. Janissen, A. Jawahery, P. W. Jeffreys, H. Jeremie, M. Jimack, M. Jobes, R. W.L. Jones, P. Jovanovic, D. Karlen, K. Kawagoe, T. Kawamoto, R. G. Kellogg, B. W. Kennedy, C. Kleinwort, D. E. Klem, G. Knop, T. Kobayashi, T. P. Kokott, L. Köpke, R. Kowalewski, H. Kreutzmann, J. Kroll, M. Kuwano, P. Kyberd, G. D. Lafferty, F. Lamarche, W. J. Larson, J. G. Layter, P. Le Du, P. Leblanc, A. M. Lee, M. H. Lehto, D. Lellouch, P. Lennert, C. Leroy, L. Lessard, S. Levegrün, L. Levinson, S. L. Lloyd, F. K. Loebinger, J. M. Lorah, B. Lorazo, M. J. Losty, J. Ludwig, J. Ma, A. A. Macbeth, M. Mannelli, S. Marcellini, G. Maringer, A. J. Martin, J. P. Martin, T. Mashimo, P. Mättig, U. Maur, T. J. McMahon, J. R. McNutt, F. Meijers, D. Menszner, F. S. Merritt, H. Mes, A. Michelini, R. P. Middleton, G. Mikenberg, J. Mildenberger, D. J. Miller, C. Milstene, M. Minowa, W. Mohr, C. Moisan, A. Montanari, T. Mori, M. W. Moss, P. G. Murphy, W. J. Murray, B. Nellen, H. H. Nguyen, M. Nozaki, A. J.P. O'Dowd, S. W. O'Neale, B. P. O'Neill, F. G. Oakham, F. Odorici, M. Ogg, H. Oh, M. J. Oreglia, S. Orito, J. P. Pansart, G. N. Patrick, S. J. Pawley, P. Pfister, J. E. Pilcher, J. L. Pinfold, D. E. Plane, B. Poli, A. Pouladdej, E. Prebys, T. W. Pritchard, H. Przysiezniak, G. Quast, M. W. Redmond, D. L. Rees, M. Regimbald, K. Riles, C. M. Roach, S. A. Robins, A. Rollnik, J. M. Roney, S. Rossberg, A. M. Rossi, P. Routenburg, K. Runge, O. Runolfsson, S. Sanghera, R. A. Sansum, M. Sasaki, B. J. Saunders, A. D. Schaile, O. Schaile, W. Schappert, P. Scharff-Hansen, S. Schreiber, J. Schwarz, A. Shapira, B. C. Shen, P. Sherwood, A. Simon, P. Singh, G. P. Siroli, A. Skuja, A. M. Smith, T. J. Smith, G. A. Snow, R. W. Springer, M. Sproston, K. Stephens, H. E. Stier, R. Stroehmer, D. Strom, H. Takeda, T. Takeshita, P. Taras, N. J. Thackray, T. Tsukamoto, M. F. Turner, G. Tysarczyk-Niemeyer, D. Van den plas, R. Van Kooten, G. J. VanDalen, G. Vasseur, C. J. Virtue, H. von der Schmitt, J. von Krogh, A. Wagner, C. Wahl, J. P. Walker, C. P. Ward, D. R. Ward, P. M. Watkins, A. T. Watson, N. K. Watson, M. Weber, S. Weisz, P. S. Wells, N. Wermes, M. Weymann, G. W. Wilson, J. A. Wilson, I. Wingerter, V. H. Winterer, N. C. Wood, S. Wotton, T. R. Wyatt, R. Yaari, Y. Yang, G. Yekutieli, T. Yoshida, W. Zeuner, G. T. Zorn

*Corresponding author for this work

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Abstract

The cross section of the pure QED process e+e-→γγ has been measured using data accumulated during the 1989 and 1990 scans of the Z0 resonance at LEP. Both the energy dependence and the angular distribution are in good agreement with the QED prediction. Upper limits on the branching ratios of Z0→γγ, Z0→π0γ and Z0→ηγ have been set at 1.4×10 -4, 1.4×10-4 and 2.0×10-4 respectively. Lower limits on the cutoff parameters of the modified electron propagator have been found to be Λ+ > 117 GeV and Λ- > 110 GeV. The reaction e+e- → γγγ has also been studied and was found to be consistent with the QED prediction. An upper limit on the branching ratio of Z0→γγγ has been set at 6.6 × 10-5. All the limits are given at 95% confidence level.

Original languageEnglish
Pages (from-to)531-540
Number of pages10
JournalPhysics Letters B
Volume257
Issue number3-4
DOIs
StatePublished - 28 Mar 1991

Funding

FundersFunder number
American Israeli Bi-national Science Foundation
Israeli Ministry of Science
Minerva Gesellschaft
National Science Foundation
U.S. Department of Energy
Natural Sciences and Engineering Research Council of Canada
Ministry of Education, Culture, Sports, Science and Technology

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