Measurement of the tt̄ production cross section in pp collisions at √s=7TeV in dilepton final states containing a τ

The top quark pair production cross section is measured in dilepton events with one electron or muon, and one hadronically decaying τ lepton from the decay tt̄→(ν)(τ hν τ)bb̄, (=e,μ). The data sample corresponds to an integrated luminosity of 2.0fb -1 for the electron channel and 2.2fb -1 for the muon channel, collected by the CMS detector at the LHC. This is the first measurement of the tt̄ cross section explicitly including τ leptons in proton-proton collisions at √s=7TeV. The measured value σ tt̄=143±14(stat)±22(syst)±3(lumi)pb is consistent with the standard model predictions. © 2012 CERN. Published by the American Physical Society.