Measurement of forward Z → e + e − production at s = 8 TeV

A measurement of the cross-section for Z-boson production in the forward region of pp collisions at 8 TeV centre-of-mass energy is presented. The measurement is based on a sample of Z → e + e − decays reconstructed using the LHCb detector, corresponding to an integrated luminosity of 2.0 fb −1 . The acceptance is defined by the requirements 2.0 < η < 4.5 and p T > 20 GeV for the pseudorapidities and transverse momenta of the leptons. Their invariant mass is required to lie in the range 60-120 GeV. The cross-section is determined to be σ pp → Z → e + e − = 93.81 ± 0.41 stat ± 1.48 syst ± 1.14 lumi p b , where the first uncertainty is statistical and the second reflects all systematic effects apart from that arising from the luminosity, which is given as the third uncertainty. Differential cross-sections are presented as functions of the Z-boson rapidity and of the angular variable ϕ ∗ , which is related to the Z-boson transverse momentum.