UC Riverside

We perform a measurement of the top quark pair production cross section in pp collisions at a center-of-mass energy of 7 TeV at the Large Hadron Collider. The analysis is based on a 36 pb^-1 dataset collected with the CMS experiment in 2010. We study the kinematic characteristics of events with exactly one isolated muon in association with additional hard jets and exhibiting substantial missing transverse energy to distinguish the tt signal from the electroweak and QCD multijet backgrounds. The signal is extracted by simultaneously fitting the tri-jet invariant mass distributions in events with exactly three jets and at least four jets. The measured cross section is 157 ± 12(stat.) ⁺²⁸_-35(syst.) ± 6(lumi.) pb, which is consistent with the theoretical predictions.