Limits on the anomalous ZZγ and Zγγ couplings in pp̅ collisions at √s = 1.8 TeV

Abstract

We performed a direct search for the anomalous ZZγ and Zγγ couplings by studying pp̅ → llγ+X (l = e,μ) events at √s = 1.8 TeV with the D0 detector at the Fermilab Tevatron Collider. A fit to the transverse energy spectrum of the photon in the signal events, based on the data set corresponding to an integrated luminosity of 14.3 pb^-1 ( 13.7 pb^-1) for the electron (muon) channel, yields the following 95% confidence level limits on the anomalous CP-conserving ZZγ couplings: |h₃₀^Z|<1.8 ( h₄₀^Z = 0) and |h₄₀^Z|<0.5 ( h₃₀^Z = 0), for a form-factor scale Λ = 500 GeV. Limits for the Zγγ couplings and CP-violating couplings are also discussed.