Electroweak vector boson production in high-energy ep collisions

Abstract

We present the results of a comprehensive study of W and Z production in high-energy ep collisions. The processes ep → eW ± X, ep → νW su− X, ep → eZ X and ep → νZ X are investigated. The region of small momentum transfer in eW and eZ production, with a fermion exchanged in the u-channel, is treated using the photon structure function approach, and carefully matched to the deep inelastic region. Low momentum photon exchange contributions to νW and eZ production, where the proton either stays intact or is transformed into a nucleon resonance, are calculated using form factors functions fitted directly to experimental data. These processes will be the source of rare but spectacular events. Total cross sections for W and Z production at HERA and at an ep collider in the LEP tunnel (LEP/LHC), and detailed results for the characteristics of eW, νW, eZ and νZ events are presented. In ep→eW X, eZ X the uncertainties of the quark densities in the proton and photon allow the total cross section predictions to vary by ±40% at HERA and ±15% at LEP/LHC.