Observation of ZZ production in pp̅ collisions at √s = 1.96 TeV

Abstract

We present an observation for ZZ→l⁺l^-l'⁺l'^- (l, l'=e or μ) production in pp̅ collisions at a center-of-mass energy of √s=1.96 TeV. Using 1.7 fb^-1 of data collected by the D0 experiment at the Fermilab Tevatron Collider, we observe three candidate events with an expected background of 0.14_-0.02^+0.03 events. The significance of this observation is 5.3 standard deviations. The combination of D0 results in this channel, as well as in ZZ→l⁺l^-νν^-, yields a significance of 5.7 standard deviations and a combined cross section of σ(ZZ)=1.60±0.63(stat)_-0.17^+0.16(syst) pb.