Measurement of the tt̅ production cross section and top quark mass extraction using Dilepton events in pp̅ collisions

Abstract

We present a measurement of the top quark pair production cross section in pp̅collisions at √s=1.96 TeV using approximately 1 fb^-1 collected with the DØ detector. We consider decay channels containing two high pT charged leptons where one lepton is identified as an electron or a muon while the other lepton can be an electron, a muon or a hadronically decaying t lepton. For a mass of the top quark of 170 GeV, the measured cross section is 7.5 ^+1.0_-1.0(stat)^+0.7._-0.6(syst) ^+0.6_-0.5(lumi) pb. Using ℓ_Τ events only, we measure: σ_tt̅×B(tt̅→ℓτbb̅)=0.13 ^+0.09_-0.08(stat) ^+0.06_-0.06(syst)^+0.02_-0.02(lumi) pb. Comparing the measured cross section as a function of the mass of the top quark with a partial next-to-next-to leading order Quantum Chromodynamics theoretical prediction, we extract a mass of the top quark of 171.5 ^+9.9_-8.8 GeV, in agreement with direct measurements.