Constraints on anomalous quartic gauge boson couplings from ννγγ and qq̄γγ 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)]