Constraints on anomalous quartic gauge boson couplings from n-ngg and q-qgg events at CERN LEP2.

Anomalous quartic couplings between the electroweak gauge bosons may contribute to the n.hivin.ngg and q.hivin.qgg final states produced in e+e- collisions. This anal. uses the LEP2 OPAL data sample at center-of-mass energies up to 209 GeV. Event selections identify n.hivin.ngg and q.hivin.qgg events in which the two photons are reconstructed within the detector acceptance. The cross section for the process e+e- -> q.hivin.qgg is measured. Averaging over all energies, the ratio of the obsd. e+e- -> q.hivin.qgg cross section to the std. model expectation is R(data/SM) = 0.92 +- 0.07 +- 0.04, where the errors represent the statistical and systematic uncertainties resp. The n.hivin.ngg and q.hivin.qgg data are used to constrain possible anomalous W+W-gg and ZZgg couplings. Combining with previous OPAL results from the W+W-g final state, the 95% confidence level limits on the anomalous coupling parameters aZ0, aZc, aW0 and aWc are found to be -0.007 GeV-2 < aZ0/L2 < 0.023 GeV-2, -0.029 GeV-2 < aZc/L2 < 0.029 GeV-2, -0.020 GeV-2 < aW0/L2 < 0.020 GeV-2, -0.052 GeV-2 < aWc/L2 < 0.037 GeV-2, where L is the energy scale of the new physics. Limits found when allowing two or more parameters to vary are also presented. [on SciFinder (R)]