Abbiendi, G and Ainsley, C and Akesson, P F and Alexander, G and Allison, J and Amaral, P and Anagnostou, G and Anderson, K J and Asai, S and Axen, D and Azuelos, G and Bailey, I and Barberio, E and Barillari, T and Barlow, R J and Batley, R J and Bechtle, P and Behnke, T and Bell, K W and Bell, P J and Bella, G and Bellerive, A and Benelli, G and Bethke, S and Biebel, O and Boeriu, O and Bock, P and Boutemeur, M and Braibant, S and Brigliadori, L and Brown, R M and Buesser, K and Burckhart, H J and Campana, S and Carnegie, R K and Carter, A A and Carter, J R and Chang, C Y and Charlton, D G and Ciocca, C and Csilling, A and Cuffiani, M and Dado, S and De Roeck, A and De Wolf, E A and Desch, K and Dienes, B and Donkers, M and Dubbert, J and Duchovni, E (2004) Constraints on anomalous quartic gauge boson couplings from nu(nu)over-bar gamma gamma and q(q)over-bar gamma gamma events at CERN LEP2. Physical Review D, 70 (3): 032005. -. ISSN 1550-7998
Abstract
Anomalous quartic couplings between the electroweak gauge bosons may contribute to the nu(nu) over bar gammagamma and q (q) over bar gammagamma 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 nu(nu) over bar gammagamma and q (q) over bar gammagamma events in which the two photons are reconstructed within the detector acceptance. The cross section for the process e(+)e(-)-->q (q) over bar gammagamma is measured. Averaging over all energies, the ratio of the observed e(+)e(-)-->q (q) over bar gammagamma 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 nu(nu) over bar gammagamma and q (q) over bar gammagamma data are used to constrain possible anomalous W(+)W(-)gammagamma and ZZgammagamma couplings. Combining with previous OPAL results from the W(+)W(-)gamma final state, the 95% confidence level limits on the anomalous coupling parameters a(0)(Z), a(c)(Z), a(0)(W) and a(c)(W) are found to be -0.007 GeV-2<a(0)(Z)/Lambda(2)<0.023 GeV-2, -0.029 GeV-2<a(c)(Z)/Lambda(2)<0.029 GeV-2, -0.020 GeV-2<a(0)(W)/Lambda(2)<0.020 GeV-2, -0.052 GeV-2<a(c)(W)/Lambda(2)<0.037 GeV-2, where Lambda is the energy scale of the new physics. Limits found when allowing two or more parameters to vary are also presented.