On theoretical uncertainties of the W angular distribution in W-pair production at LEP2 energies

We discuss theoretical uncertainties of the distribution in the cosine of the W polar angle projected into a measurement of the anomalous triple gauge-boson coupling λ=λγ=λZ at LEP2 energies for the tandem of the Monte Carlo event generators KoralW and YFSWW3 and for the Monte Carlo event generator RacoonWW. Exploiting numerical results of these programs and cross-checks with experimental fitting procedures, we estimate that the theoretical uncertainty of the value of λ due to electroweak corrections, as obtained at LEP2 with the help of these programs, is ∼0.005, about half of the expected experimental error for the combined LEP2 experiments (∼0.010). We use certain idealized event selections; however, we argue that these results are valid for realistic LEP2 measurements.