Production of electroweak gauge bosons in off-shell gluon-gluon fusion

Abstract

We study the production of electroweak gauge bosons at high energies in the framework of k{sub T}-factorization QCD approach. The amplitude for production of a single W{sup {+-}} or Z{sup 0} boson associated with quark pair in the fusion of two off-shell gluons is calculated. Contributions from the valence quarks are calculated using the quark-gluon interaction and quark-antiquark annihilation QCD subprocesses. The total and differential cross sections (as a function of the transverse momentum and rapidity) are presented and the ratio of cross sections for W{sup {+-}} and Z{sup 0} boson production is investigated. The conservative error analysis is performed. In the numerical calculations two different sets of unintegrated gluon distributions in the proton are used: the one obtained from the Ciafaloni-Catani-Fiorani-Marchesini evolution equation and the other from the Kimber-Martin-Ryskin prescription. Theoretical results are compared with experimental data taken by the D0 and CDF collaborations at the Tevatron. We demonstrate the importance of the quark component in parton evolution in description of the experimental data. This component is very significant also at the LHC energies.