Measurement of thett¯production cross section in pp collisions ats=7TeVin dilepton final states containing aτ

The top quark pair production cross section is measured in dilepton events with one electron or muon, and one hadronically decaying $\ensuremath{\tau}$ lepton from the decay $t\overline{t}\ensuremath{\rightarrow}(\ensuremath{\ell}{\ensuremath{\nu}}_{\ensuremath{\ell}})({\ensuremath{\tau}}_{\mathrm{h}}{\ensuremath{\nu}}_{\ensuremath{\tau}})\mathrm{b}\overline{\mathrm{b}}$, ($\ensuremath{\ell}=e,\ensuremath{\mu}$). The data sample corresponds to an integrated luminosity of $2.0\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ for the electron channel and $2.2\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ for the muon channel, collected by the CMS detector at the LHC. This is the first measurement of the $t\overline{t}$ cross section explicitly including $\ensuremath{\tau}$ leptons in proton-proton collisions at $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$. The measured value ${\ensuremath{\sigma}}_{t\overline{t}}=143\ifmmode\pm\else\textpm\fi{}14(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}22(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}3(\mathrm{lumi})\text{ }\text{ }\mathrm{pb}$ is consistent with the standard model predictions.