Z-boson pair production via gluon fusion

Abstract

We study the coupling of two gluons with two Z-bosons via a quark loop keeping the full dependence on the quark mass. We discuss the structure of the ggZZ polarisation tensor and give explicit formulas for the helicity amplitudes. The results are used to study the production of Z-boson pairs at hadron colliders both with and without the presence of a Higgs boson. Invariant mass, transverse momentum and rapidity distributions of the produced Z-bosons are shown. The Z-bosons from the gluon fusion process are produced somewhat more centrally than those from the quark-antiquark background. The continuum gluon fusion process, gg → ZZ, is important, (60–70%), but never dominant over the q q → ZZ process at the SSC. The Higgs boson signal and the continnum background interfere destructively at large s ̂ and this leads to a reduction in the cross section at large invariant mass and transverse momentum.