Measurement of the top quark pair production cross section with ATLAS in pp collisions at sqrt{s}=7TeV in the single-lepton channel using semileptonic b decays

The cross section for top quark pair production in pp collisions at sqrt{s} = 7 TeV is measured using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected requiring a single high pT isolated electron or muon, missing transverse momentum and jets. Semileptonic b decays are identified by a lower momentum muon close to a jet, leading to substantially different sources of systematic uncertainty compared with other measurements. With a data sample corresponding to 4.66 fb^{-1} of integrated luminosity the top quark pair production cross section is measured to be sigma_{tar{t}} = 165 + 2(stat.) + 17(syst.) + 3(lumi.) pb In agreement with a theoretical prediction of 167 $pm$ 18 pb based on perturbative QCD and with other measurements which used different techniques or decay channels.