1. Multi-photon events with large missing energy in e+e− collisions at s=192–209 GeV
- Author
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James Pinfold, R. Seuster, P. Scharff-Hansen, A. M. Smith, Andris Skuja, Tetsuro Mashimo, M. F. Turner-Watson, N. Meyer, M. Kupper, Daniel Lellouch, Takehiko Mori, L. Brigliadori, T. Behnke, S. W. O'Neale, P. O. Günther, J. Goldberg, M. Boutemeur, F. S. Merritt, K. J. Anderson, Thorsten Wengler, B. C. Shen, M. Donkers, Yoram Rozen, Siegfried Bethke, J. A. McKenna, Tara Shears, W. G. Scott, S. Yamashita, Junichi Kanzaki, Silvia Arcelli, J. W. Gary, P. Igo-Kemenes, K. Buesser, M. Gruwé, K. Ishii, H. Jeremie, Gideon Bella, Gianni Masetti, C. Y. Chang, R. M. Brown, Lorne Levinson, Christoph Rembser, Christoph Geich-Gimbel, Teresa Barillari, H. J. Burckhart, A. Csilling, S. Moed, Gabriele Benelli, Guenter Duckeck, D. Axen, Dezso Horvath, Erez Etzion, Richard Nisius, Graham Wilson, I. R. Bailey, O. Schaile, Oana Elena Vickey Boeriu, Raimund Ströhmer, Stefan Kluth, T. Kuhl, Shlomit Tarem, P. Mättig, Shoji Asai, Marco Cuffiani, Shlomo Dado, Richard Teuscher, A. J. Martin, F. Spano, M. J. Oreglia, M. Hauschild, M. Giunta, D. Zer-Zion, Robert McPherson, L. Zivkovic, Lutz Feld, D. Toya, P. J. Bell, G. Gaycken, W. Mader, Beatrix Dienes, F. K. Loebinger, C. Pahl, Giora Mikenberg, M. Schumacher, Matthias Schröder, Alexander Oh, J. R. Carter, W. Menges, Otmar Biebel, Paolo Giacomelli, Ivor Fleck, J. Ludwig, K. Runge, P. Bock, Georges Azuelos, T. R. Wyatt, I. Nakamura, D. Lanske, T. R. Junk, A. D. Schaile, Joleen Pater, Edward K. G. Sarkisyan, Gabriella Pasztor, K. Hoffman, E. Tsur, Gregor Herten, C. M. Hawkes, E. A. De Wolf, P. Vannerem, H. Nanjo, T. Schörner-Sadenius, Fabrizio Fabbri, A. Frey, Balazs Ujvari, H. A. Neal, Isabel Marian Trigger, K. W. Bell, A. Gupta, C. F. Vollmer, C. P. Ward, P. Gagnon, A. Harel, J. E. Pilcher, J. C. Hill, George Lafferty, Norbert Wermes, T. Kawamoto, Jochen Schieck, Ikuo Ueda, D. M. Strom, R. J. Barlow, J. Lu, Tobias Kramer, P. Amaral, Satoshi Mihara, S. Söldner-Rembold, Gunter Wolf, S. Orito, Zoltan Laszlo Trocsanyi, Kiyotomo Kawagoe, Gideon Alexander, D. Karlen, Frank Fiedler, B. Poli, R. K. Keeler, Dave Charlton, P. S. Wells, Arnulf Quadt, H. Mes, P. M. Watkins, A. T. Watson, Klaus Rabbertz, I. P. Duerdoth, S. Braibant, P. Renkel, Stephen Lloyd, P. Sherwood, Achim Stahl, Oliver Pooth, Ehud Duchovni, John Allison, D. E. Plane, N. Kanaya, A. Michelini, R. G. Kellogg, M. Hamann, R. D. Heuer, Csaba Hajdu, T. Kobayashi, A. Ludwig, Stefano Marcellini, Claudia Ciocca, James Letts, R. Vértesi, R. J. Sobie, Joost Vossebeld, Klaus Desch, P. Tran, K. Sachs, Philip Bechtle, Gordon H. Hanson, D. R. Ward, M. Ford, N. K. Watson, R. J. Batley, S. Campana, C. Ainsley, J. von Krogh, R. J. Hawkings, J. Dubbert, R. K. Carnegie, J. A. Wilson, M. A. Thomson, E. K. U. Gross, Eric Torrence, D. J. Miller, R. J. Hemingway, J. Lillich, B. W. Kennedy, P. Jovanovic, Peter Krieger, M. Przybycień, H. Landsman, A. A. Carter, E. L. Barberio, M. Verzocchi, P. F. Åkesson, Giovanni Abbiendi, J. M. Roney, M. Tasevsky, Koichi Nagai, W. Mohr, J. Grunhaus, A. Mutter, Sachio Komamiya, K. Kruger, T. Saeki, J. G. Layter, Alain Bellerive, G. Anagnostou, H. Voss, G. Giacomelli, Pamela Ferrari, A. De Roeck, M. Kobel, and Frans Meijers
- Subjects
Physics ,Nuclear and High Energy Physics ,Particle physics ,Missing energy ,010308 nuclear & particles physics ,Electron–positron annihilation ,01 natural sciences ,7. Clean energy ,Nuclear physics ,Massless particle ,Pair production ,Excited state ,0103 physical sciences ,Neutralino ,Gravitino ,010306 general physics ,Bhabha scattering - Abstract
Events with a final state consisting of two or more photons and large missing transverse energy have been observed in e + e − collisions at centre-of-mass energies in the range 192–209 GeV using the OPAL detector at LEP. Cross-section measurements are performed within the kinematic acceptance of the selection and compared with the expectations from the Standard Model process e + e − → ν ν ¯ γ γ ( γ ) . No evidence for new physics contributions to this final state is observed. Upper limits on σ ( e + e − → X X ) ⋅ BR 2 ( X → Y γ ) are derived for the case of stable and invisible Y. In the case of massive Y the combined limits obtained from all the data range from 10 to 60 fb, while for the special case of massless Y the range is 20 to 40 fb. The limits apply to pair production of excited neutrinos ( X = ν * , Y = ν ), to neutralino production ( X = χ ˜ 2 0 , Y = χ ˜ 1 0 ) and to supersymmetric models in which X = χ ˜ 1 0 and Y = G ˜ is a light gravitino.
- Published
- 2004