The top-quark pair production cross section in 7 TeV center-of-mass energy proton–proton collisions is measured using data collected by the CMS detector at the LHC. The measurement uses events with one jet identified as a hadronically decaying τ lepton and at least four additional energetic jets, at least one of which is identified as coming from a b quark. The analyzed data sample corresponds to an integrated luminosity of 3.9 fb−1 recorded by a dedicated multijet plus hadronically decaying τ trigger. A neural network has been developed to separate the top-quark pairs from the W+jets and multijet backgrounds. The measured value of σtt¯ = 152 ± 12 (stat.) ± 32 (syst.) ±3 (lum.) pb is consistent with the standard model predictions.
CMS Collaboration (2013). Measurement of the tt¯ production cross section in the τ +jets channel in pp collisions at √s =7 TeV. European Physical Journal C, 73(4), . https://doi.org/10.1140/epjc/s10052-013-2386-x