Publication
Title
Study of W-boson polarisations and triple gauge boson couplings in the reaction $e^{+}e^{-}\rightarrow W^{+}W^{-}$ at LEP 2
Author
Institution/Organisation
DELPHI Collaboration
Abstract
 A determination of the single W spin density matrix (SDM) elements in the reaction e+e-→W+W-→lνqq̄(l=e/μ) is reported at centre-of-mass energies between 189 and 209 GeV. The data sample used corresponds to an integrated luminosity of 520 pb-1 taken by DELPHI between 1998 and 2000. The single W SDM elements, ρττ W± (τ,τ=± 1 or 0), are determined as a function of the W- production angle with respect to the e- beam direction and are obtained from measurements of the W decay products by the application of suitable projection operators, Λττ, which assume the V-A coupling of the W-boson to fermions. The measured SDM elements are used to obtain the fraction of longitudinally polarised Ws, with the result: $\frac{\sigma_{\text{L}}}{\sigma_{{\text{tot}}}} = 24.9 \pm4.5({\text{stat}}) \pm2.2({\text{syst}})\%$ at a mean energy of 198 GeV. The SDM elements are also used to determine the triple gauge couplings Δg1 Z,Δκγ,λγ and g4 Z, $\tilde{\kappa}_{Z}$ and $\tilde{\lambda}_{Z}$. For the CP-violating couplings the results of single parameter fits are: \$g_4
Language
English
Source (journal)
European physical journal : C : particles and fields. - Berlin
Publication
Berlin : 2008
ISSN
1434-6044
Volume/pages
54:3(2008), p. 345-364
ISI
000254206800001
Full text (Publisher's DOI)
UAntwerpen
 Faculty/Department Research group Publication type Subject