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

Abstract: 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 beσpp→Z→e+e−=93.81±0.41stat±1.48syst±1.14lumipb,$$ \sigma \left(\mathrm{pp}\to \mathrm{Z}\to {\mathrm{e}}^{+}{\mathrm{e}}^{-}\right)=93.81\pm 0.41\left(\mathrm{stat}\right)\pm 1.48\left(\mathrm{syst}\right)\pm 1.14\left(\mathrm{lumi}\right)\mathrm{p}\mathrm{b}, $$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.[Figure not available: see fulltext.]