Determination of the LEP centre-of-mass energy from Zγ events

Laboratoire de l'Accélérateur Linéaire
European Organization for Nuclear Research
Sezione di Ferrara Istituto Nazionale di Fisica Nucleare
Sezione di Milano Istituto Nazionale di Fisica Nucleare
Sezione di Bari Istituto Nazionale di Fisica Nucleare
CSFNSM Centro Siciliano di Fisica Nuclear e Struttura della Materia
Service de Physique des Particules
Faculté des Sciences de Tunis Université de Tunis El Manar
Santa Cruz Institute for Particle Physics
SAP AG
University of Wisconsin Madison
Johannes Gutenberg Universität Mainz
Institute of High Energy Physics Chinese Academy of Science
Università di Pisa
Universität Siegen
IN2P3 Institut National de Physique Nucleaire et de Physique des Particules
Rutherford Appleton Laboratory
Lancaster University
Universitat Autònoma de Barcelona
Max Planck Institut für Astrophysik

Abstract

A study of events with photons and missing energy has been performed with the data sample obtained with the ALEPH detector at centre-of-mass energies from 161 to 184 GeV, corresponding to a total integrated luminosity of about 80 pb−1. The measured distributions are in agreement with Standard Model predictions, leading to constraints on WWγ gauge coupling parameters ∆κγ and λγ. The results from the fit to the cross sections and to the energy and angular distributions of the photons are: ∆κγ = 0.05+1.15 −1.10(stat)±0.25(syst) λγ = −0.05+1.55 −1.45(stat)±0.30(syst).