A study of the $Z$ production cross-section in $pp$ collisions at $s = 7$ TeV using tau final states

A measurement of the inclusive Z→ττ cross-section in pp collisions at s√=7 TeV is presented based on a dataset of 1.0 fb−1 collected by the LHCb detector. Candidates for Z→ττ decays are identified through reconstructed final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. The production cross-section for Z bosons, with invariant mass between 60 and 120 GeV/c2, which decay to τ leptons with transverse momenta greater than 20 GeV/c and pseudorapidities between 2.0 and 4.5, is measured to be σpp→Z→ττ=71.4±3.5±2.8±2.5 pb; the first uncertainty is statistical, the second uncertainty is systematic, and the third is due to the uncertainty on the integrated luminosity. The ratio of the cross-sections for Z→ττ to Z→μμ is determined to be 0.93±0.09, where the uncertainty is the combination of statistical, systematic, and luminosity uncertainties of the two measurements.
A measurement of the inclusive Z → ττ cross-section in pp collisions at is presented based on a dataset of 1.0 fb(−1) collected by the LHCb detector. Candidates for Z → τ τ decays are identified through reconstructed final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. The production cross-section for Z bosons, with invariant mass between 60 and 120 GeV/c (2), which decay to τ leptons with transverse momenta greater than 20 GeV/c and pseudorapidities between 2.0 and 4.5, is measured to be σ( )pp(→Z→)ττ( ) = 71.4 ± 3.5 ± 2.8 ± 2.5 pb, the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the integrated luminosity. The ratio of the cross-sections for Z → τ τ to Z → μμ is determined to be 0.93 ± 0.09, where the uncertainty is the combination of statistical, systematic, and luminosity uncertainties of the two measurements.