Limits on Anomalous Trilinear Gauge Couplings in Zγ Events from pp̅ Collisions at √s=1.96 TeV

Abstract

Using Zγ candidate events collected by the CDF detector at the Tevatron Collider, we search for potential anomalous (non-standard-model) couplings between the Z boson and the photon. Zγ couplings vanish at tree level and are heavily suppressed at higher orders; hence any evidence of couplings indicates new physics. Measurements are performed using data corresponding to an integrated luminosity of 4.9 fb[superscript -1] in the Z→νν̅ decay channel and 5.1 fb[superscript -1] in the Z→l[superscript +]l[superscript -] (l=μ, e) decay channels. The combination of these measurements provides the most stringent limits to date on Zγ trilinear gauge couplings. Using an energy scale of Λ=1.5 TeV to allow for a direct comparison with previous measurements, we find limits on the CP-conserving parameters that describe Zγ couplings to be |h[subscript 3][superscript γ,Z]|<0.022 and |h[subscript 4][superscript γ,Z]|<0.0009. These results are consistent with standard model predictions.