Zγ production and limits on anomalous ZZγ and Zγγ couplings in p over(p, ̄) collisions at sqrt(s) = 1.96 TeV

Abstract We present a study of eeγ and μμγ events using 1109 (1009) pb −1 of data in the electron (muon) channel, respectively. These data were collected with the DO detector at the Fermilab Tevatron p p ¯ collider at s = 1.96 TeV . Having observed 453 (515) candidates in the eeγ ( μμγ ) final state, we measure the Zγ production cross section for a photon with transverse energy E T > 7 GeV , separation between the photon and leptons Δ R l γ > 0.7 , and invariant mass of the di-lepton pair M l l > 30 GeV / c 2 , to be 4.96 ± 0.30 ( stat . + syst . ) ± 0.30 ( lumi . ) pb , in agreement with the Standard Model prediction of 4.74 ± 0.22 pb . This is the most precise Zγ cross section measurement at a hadron collider. We set limits on anomalous trilinear Zγγ and ZZγ gauge boson couplings of − 0.085 h 30 γ 0.084 , − 0.0053 h 40 γ 0.0054 and − 0.083 h 30 Z 0.082 , − 0.0053 h 40 Z 0.0054 at the 95% C.L. for the form-factor scale Λ = 1.2 TeV .