W-pair production in the processe+e−→lνqq¯′ and measurement of theWWγ andWWZcouplings

We perform a detailed analysis of the process ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$→lνqq¯′ where we include all tree level Feynman diagrams that contribute to this final state. We study the sensitivity of this process to anomalous trilinear gauge boson couplings of the WWγ and WWZ vertices using two popular parametrizations. We use a maximum likelihood analysis of a five-dimensional differential cross section based on the W and W decay product angular distributions. We concentrate on CERN LEP 200 energies, taking √s =175 GeV, and energies appropriate to the proposed Next Linear Collider, a high energy ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$ collider with center-of-mass energies √s =500 and 1 TeV. At 175 GeV, ${\mathit{g}}_1^{\mathit{Z}}$ can be measured to about ±0.2, ${\mathrm{\kappa }}_{\mathit{Z}}$ to ±0.2, and ${\mathrm{\kappa }}_{\gamma }$ to ±0.3 ${\lambda }_{\mathit{Z}}$ to ±0.2 and ${\lambda }_{\gamma }$ to ±0.3 at 95% C.L. assuming 500 ${\mathrm{pb}}^{\mathrm{-}1}$ integrated luminosity. Although these will be improvements of existing measurements they are not sufficiently precise to test the standard model at the loop level and are unlikely to see deviations from SM expectations. At 500 GeV with 50 ${\mathrm{fb}}^{\mathrm{-}1}$ integrated luminosity, ${\mathit{g}}_1^{\mathit{Z}}$ can be measured to about ±0.01, ${\mathrm{\kappa }}_{\mathit{Z}}$ and ${\mathrm{\kappa }}_{\gamma }$ to ±0.005 and ${\lambda }_{\mathit{Z}}$ and ${\lambda }_{\gamma }$ to ±0.003 at 95% C.L. while at 1 TeV with 200 ${\mathrm{fb}}^{\mathrm{-}1}$ integrated luminosity, ${\mathrm{\kappa }}_{\mathit{V}}$ and ${\lambda }_{\mathit{V}}$ can be measured to about ±0.005 and ±${10}^{\mathrm{-}3}$, respectively. The 500 GeV measurements will be at the level of loop contributions to the couplings and may show hints of new physics while the 1 TeV should be sensitive to new physics at the loop level.