A study of single W production in e+e- collisions at √s = 161-183 GeV

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
Johannes Gutenberg Universität Mainz
Università di Pisa
IN2P3 Institut National de Physique Nucleaire et de Physique des Particules
Institute of High Energy Physics Chinese Academy of Science
Lancaster University
Universität Siegen
Universitat Autònoma de Barcelona
Rutherford Appleton Laboratory
Consiglio Nazionale delle Ricerche
Università degli Studi di Firenze

Abstract

Single W production is studied in the data recorded with the ALEPH detector at LEP at centre-of-mass energies between 161 and 183 GeV. The cross section is measured to be σw = 0.41 ± 0.17(stat.) ± 0.04(syst.) pb at 183 GeV, consistent with the Standard Model expectation. Limits on non-standard WWγ couplings are deduced as -1.6 γ γ = 0) and -1.6 γ γ = 1) at 95% C.L. A search for effectively invisible decays of the W boson in W pair production is performed, leading to an upper limit on the branching ratio of 1.3% (Γinv = 27 MeV) at 95% C.L.