Search for ZZ and Z\gamma^* production in p-barp collisions at sqrt(s) = 1.96 TeV and limits on anomalous ZZZ and ZZ\gamma^* couplings

TL;DR

This study searches for ZZ and Zγ* production in proton-antiproton collisions at 1.96 TeV, setting limits on their cross section and on anomalous ZZZ and ZZγ* couplings based on observed events and background estimates.

Contribution

It provides the first limits on anomalous neutral trilinear ZZZ and ZZγ* couplings at Tevatron energies using four-lepton event data.

Findings

Observed one event consistent with background and Standard Model predictions.

Set an upper limit of 4.4 pb on ZZ and Zγ* production cross section.

Derived limits on anomalous ZZZ and ZZγ* couplings at 95% confidence level.

Abstract

We present a study of four muon, four electron, and two muon two electron events using 1 fb^(-1) of data collected with the D0 detector at the Fermilab Tevatron p-barp Collider at sqrt(s) = 1.96 TeV. Requiring the lepton pair masses to be greater than 30 GeV, we observe one event, consistent with the expected background of 0.13 +- 0.03 events and with the predicted standard model ZZ and Z\gamma^* production of 1.71 +-0.15 events. We set an upper limit on the ZZ and Z\gamma^* cross section of 4.4 pb at the 95% C.L. We also derive limits on anomalous neutral trilinear ZZZ and ZZ\gamma^* gauge couplings. The one-parameter 95%$ C.L. coupling limits with a form factor scale Lambda = 1.2 TeV are -0.28 < f_(40)^Z < 0.28, -0.31 < f_(50)^Z < 0.29, -0.26 < f_(40)^\gamma < 0.26, and -0.30 < f_(5 0)^\gamma < 0.28.