First Observation of Vector Boson Pairs in a Hadronic Final State at the Tevatron Collider

We present the first observation in hadronic collisions of the electroweak production of vector boson pairs ($VV$, $V=W$, $Z$) where one boson decays to a dijet final state. The data correspond to $3.5{\mathrm{fb}}^{-1}$ of integrated luminosity of $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ collected by the CDF II detector at the Fermilab Tevatron. We observe $1516\pm 239(\mathrm{stat})\pm 144(\mathrm{syst})$ diboson candidate events and measure a cross section $\sigma (p\overline{p}\to VV+X)$ of $18.0\pm 2.8(\mathrm{stat})\pm 2.4(\mathrm{syst})\pm 1.1(\mathrm{lumi})\mathrm{pb}$, in agreement with the expectations of the standard model.