| We present the measurement of the tt¯ cross section in the lepton plus jets channel with ≥ 1 and ≥ 2 secondary vertex tags. We use the scalar sum of transverse energies of the event (H T) to discriminate tt¯ from the other backgrounds. We also use the transverse mass of the leptonic W-boson ( MWT ) to further reduce the Non-W backgrounds. We use a combination of data and Monte Carlo to estimate the backgrounds from electroweak processes, single top, fake leptons, W+ Light Flavor fake tags, and real W+ Heavy Flavor production.; We obtain a value of sigma≥1 = 8.7+0.9-0.9stat +1.2-0.9sys pb for the ≥ 1 tag cross section, and sigma≥2 = 8.7+1.8-1.6stat +1.9-1.3sys pb for the ≥ 2 tag cross section.; We also present a measurement of the tt¯ cross section by fitting the Njet spectrum. We combine the = 1 and ≥ 2 tag cross sections to obtain sigmatt¯ = 8.7+0.9-0.9stat +1.4-1.3syst pb. |
