Measurement of the tt¯ production cross section in pp collisions at ?s=7TeV in dilepton final states containing a ?

The top quark pair production cross section is measured in dilepton events with one electron or muon, and one hadronically decaying ? lepton from the decay tt¯›(?)(? h? ?)bb¯, (=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 tt¯ cross section explicitly including ? leptons in proton-proton collisions at ?s=7TeV. The measured value ? tt¯=143±14(stat)±22(syst)±3(lumi)pb is consistent with the standard model predictions. © 2012 CERN. Published by the American Physical Society