Measurement of the e+e- -> Z gamma gamma Cross Section and Determination of Quartic Gauge Boson Couplings at LEP
L3 Collaboration
Abstract
A first measurement of the cross section of the process e+e- -> Z gamma gamma is reported using a total integrated luminosity of 231 pb-1 collected with the L3 detector at centre-of-mass energies of 182.7 GeV and 188.7 GeV. By selecting hadronic events with two isolated photons the e+e- -> Z gamma gamma cross section is measured to be 0.49 +0.20 -0.17 +/- 0.04 pb at 182.7 GeV and 0.47 +/- 0.10 +/- 0.04 pb at 188.7 GeV. The measurements are consistent with Standard Model expectations. Limits on Quartic Gauge Boson Couplings a0/Lambda2 and ac/Lambda2 of -0.009 GeV-2 < a0/Lambda2 < 0.008 GeV-2 and -0.007 GeV-2 < ac/Lambda2 < 0.013 GeV-2 are derived at 95% confidence level.
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