Eur. Phys. J. C (1998) 1: 21-30
https://doi.org/10.1007/BF01245795

Multi-photon final states in e⁺e⁻ collisions at ∝s =130-172 GeV

¹⁴ School of Physics and Space Research, University of Birmingham, B15 2TT, Birmingham, UK
⁷ Dipartimento di Fisica dell' Università di Bologna and INFN, I-40126, Bologna, Italy
¹² Physikalisches Institut, Universität Bonn, D-53115, Bonn, Germany
²³ Department of Physics, University of California, 92521, Riverside, CA, USA
⁴ Cavendish Laboratory, CB3 0HE, Cambridge, UK
²⁰ Ottawa-Carleton Institute for Physics, Department of Physics, Carleton University, K1S 5B6, Ottawa, Ontario, Canada
²⁹ Centre for Research in Particle Physics, Carleton University, K1S 5B6, Ottawa, Ontario, Canada
¹ CERN, European Organisation for Particle Physics, CH-1211, Geneva 23, Switzerland
⁵ Enrico Fermi Institute and Department of Physics, University of Chicago, 60637, Chicago, IL, USA
¹⁷ Fakultät für Physik, Albert Ludwigs Universität, D-79104, Freiburg, Germany
¹⁸ Physikalisches Institut, Universität Heidelberg, D-69120, Heidelberg, Germany
⁶ Department of Physics, Indiana University, Swain Hall West 117, 47405, Bloomington, IN, USA
²¹ Queen Mary and Westfield College, University of London, E1 4NS, London, UK
¹³ III Physikalisches Institut, Technische Hochschule Aachen, Sommerfeldstrasse 26-28, D-52056, Aachen, Germany
²⁴ University College London, WC1E 6BT, London, UK
³ Department of Physics, Schuster Laboratory, The University, M13 9PL, Manchester, UK
¹¹ Department of Physics, University of Maryland, 20742, College Park, MD, USA
⁹ Laboratoire de Physique Nucléaire, Université de Montréal, H3C 3J7, Montréal, Quebec, Canada
³⁶ Department of Physics, University of Oregon, 97403, Eugene, OR, USA
¹⁵ Rutherford Appleton Laboratory, OX11 0QX, Chilton, Didcot, Oxfordshire, UK
²⁵ Department of Physics, Technion-Israel Institute of Technology, 32000, Haifa, Israel
² Department of Physics and Astronomy, Tel Aviv University, 69978, Tel Aviv, Israel
⁸ International Centre for Elementary Particle Physics and Department of Physics, University of Tokyo, Tokyo, 113, Japan
³² Brunel University, U138 3PH, Uxbridge, Middlesex, UK
³⁰ Particle Physics Department, Weizmann Institute of Science, 76100, Rehovot, Israel
¹⁶ II Institut für Experimental Physik, Universität Hamburg/DESY, Notkestrasse 85, D-22607, Hamburg, Germany
³³ Department of Physics, University of Victoria, P O Box 3055, V8W 3P6, Victoria, BC, Canada
³⁵ Department of Physics, University of British Columbia, V6T 1Z1, Vancouver, BC, Canada
²⁶ Department of Physics, University of Alberta, T6G 2J1, Edmonton, AB, Canada
³⁷ Dept of Physics, Duke University, 27708-0305, Durham, NC, USA
³¹ Research Institute for Particle and Nuclear Physics, P O Box 49, H-1525, Budapest, Hungary
²⁷ Institute of Nuclear Research, P O Box 51, H-4001, Debrecen, Hungary
¹⁹ Sektion Physik, Ludwigs-Maximilians-Universitat München, Am Coulombwall 1, D-85748, Garching, Germany
¹⁰ TRIUMF, V6T 2A3, Vancouver, Canada
²² Royal Society University Research Fellow, Canada
³⁴ Institute of Nuclear Research, Debrecen, Hungary
²⁸ Department of Experimental Physics, Lajos Kossuth University, Debrecen, Hungary
³⁸ Department of Physics, New York University, 1003, NY, USA

Received: 11 August 1997
Published online: 27 February 2005

Abstract

The process e⁺e⁻ →, γγ(γ) is studied using data recorded with the OPAL detector at LEP. The data sample corresponds to a total integrated luminosity of 25.38 pb⁻¹ taken at centre-of-mass energies of 130–172 GeV. The measured cross-sections agree well with the expectation from QED. In a combined fit using data from all centre-of-mass energies, the angular distribution is used to obtain improved limits on the cut-off parameters: Λ₊ > 195 GeV and Λ₋ > 210 GeV (95% CL). In addition, limits on nonstandard e⁺e⁻γ couplings and contact interactions, as well as a 95% CL mass limit for an excited electron,Me^*= > 194 GeV for an e⁺e⁻γ coupling κ = 1, are determined.