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Title
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Study of W-boson polarisations and triple gauge boson couplings in the reaction at LEP 2
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Author
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Institution/Organisation
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DELPHI Collaboration
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Abstract
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| 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 |
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Language
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English
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Source (journal)
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European physical journal : C : particles and fields. - Berlin
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Publication
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Berlin
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2008
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ISSN
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1434-6044
1434-6052
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DOI
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10.1140/EPJC/S10052-008-0528-3
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Volume/pages
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54
:3
(2008)
, p. 345-364
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ISI
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000254206800001
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Full text (Publisher's DOI)
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