Abbiendi, G. et al. (2004) Constraints on anomalous quartic gauge boson couplings from νν[over ¯]γγ and qq[over ¯]γγ events at CERN LEP2. Physical Review D, 70 (3). 032005. ISSN 1550-7998

Anomalous quartic couplings between the electroweak gauge bosons may contribute to the νν̅ γγ and qq̅ γγ final states produced in e+e- collisions. This analysis uses the LEP2 OPAL data sample at center-of-mass energies up to 209 GeV. Event selections identify νν̅ γγ and qq̅ γγ events in which the two photons are reconstructed within the detector acceptance. The cross section for the process e+e-→qq̅ γγ is measured. Averaging over all energies, the ratio of the observed e+e-→qq̅ γγ cross section to the standard model expectation is R(data/SM)=0.92±0.07±0.04, where the errors represent the statistical and systematic uncertainties respectively. The νν̅ γγ and qq̅ γγ data are used to constrain possible anomalous W+W-γγ and ZZγγ couplings. Combining with previous OPAL results from the W+W-γ final state, the 95% confidence level limits on the anomalous coupling parameters a0Z, acZ, a0W and acW are found to be -0.007 GeV-2<a0Z/Λ2<0.023 GeV-2, -0.029 GeV-2<acZ/Λ2<0.029 GeV-2, -0.020 GeV-2<a0W/Λ2<0.020 GeV-2, -0.052 GeV-2<acW/Λ2<0.037 GeV-2, where Λ is the energy scale of the new physics. Limits found when allowing two or more parameters to vary are also presented.

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