2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 8, 191-215
DOI 10.1007/s100529901106

$\mathrm{W^+W^-}$ production and triple gauge boson couplings at LEP energies up to 183 GeV

The OPAL Collaboration
G. Abbiendi 2 - et al.

2Dipartimento di Fisica dell' Università di Bologna and INFN, I-40126 Bologna, Italy

Received: 23 October 1998 / Published online: 1 March 1999

Abstract
A study of W-pair production in ${\rm e^+e^-}$ annihilations at LEP is presented, based on $877\,{\rm W^+W^-}$ candidates corresponding to an integrated luminosity of $57\,{\rm pb}^{-1}$ at $\sqrt
s=183$ GeV. Assuming that the angular distributions of the W-pair production and decay, as well as their branching fractions, are described by the Standard Model, the W-pair production cross-section is measured to be $15.43\pm 0.61 ({\rm stat.}) \pm 0.26 ({\rm syst.})$pb. Assuming lepton universality and combining with our results from lower centre-of-mass energies, the W branching fraction to hadrons is determined to be $67.9 \pm 1.2 ({\rm stat.})\pm 0.5 ({\rm syst.})$%. The number of W-pair candidates and the angular distributions for each final state (${\rm q \bar q} \bar \ell \nu_\ell$,${\rm q \bar q q \bar q}, \bar \ell \nu_\ell \ell^\prime \bar
\nu_{\ell^\prime })$are used to determine the triple gauge boson couplings. After combining these values with our results from lower centre-of-mass energies we obtain $\Delta \kappa_\gamma = 0.11^{+0.52}_{-0.37}$, $\Delta
g^{\rm z}_1
=
0.01^{+ 0.13}_{-0.12}$ and $\lambda = -0.10^{+0.13}_{-0.12}$,where the errors include both statistical and systematic uncertainties and each coupling is determined by setting the other two couplings to the Standard Model value. The fraction of W bosons produced with a longitudinal polarisation is measured to be $0.242 \pm 0.091({\rm stat.}) \pm 0.023 ({\rm syst.})$. All these measurements are consistent with the Standard Model expectations.


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