Measurement of the $t \bar t$ Production Cross Section in $pp$ Collisions at $\sqrt s = 8$ TeV in Dilepton Final States Containing One $\tau$ Lepton

The top-quark pair production cross section is measured in final states with one electron or muon and one hadronically decaying τ lepton from the process tt¯→(ℓνℓ)(τντ)bb¯ , where ℓ=e,μ . The data sample corresponds to an integrated luminosity of 19.6 fb −1 collected with the CMS detector in proton–proton collisions at s=8 TeV . The measured cross section σtt¯=257±3 (stat)±24 (syst)±7 (lumi) pb , assuming a top-quark mass of 172.5 GeV, is consistent with the standard model prediction.