Measurement of the tt¯ production cross section and top quark mass extraction using dilepton events in pp¯ collisions

We present a measurement of the top quark pair production cross section in pp¯ collisions at s=1.96TeV 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 τ lepton. For a mass of the top quark of 170 GeV, the measured cross section is 7.5−1.0+1.0(stat)−0.6+0.7(syst)−0.5+0.6(lumi)pb. Using ℓτ events only, we measure: σtt¯×B(tt¯→ℓτbb¯)=0.13−0.08+0.09(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 171.5−8.8+9.9GeV, in agreement with direct measurements.