We present a measurement of the inclusive top quark pair production cross
section in \ppbar collisions at (\sqrt{s}=1.96) TeV utilizing data
corresponding to an integrated luminosity of \lumi\ collected with the D0
detector at the Fermilab Tevatron Collider. We consider final states containing
one high-pT isolated electron or muon and at least two jets, and we
perform three analyses: one exploiting specific kinematic features of \ttbar
events, the second using b-jet identification, and the third using both
techniques to separate \ttbar\ signal from background. In the third case, we
determine simultaneously the ttˉ cross section and the ratio of the
production rates of W+heavy flavor jets and W+light flavor jets, which
reduces the impact of the systematic uncertainties related to the background
estimation. Assuming a top quark mass of 172.5 GeV, we obtain
σttˉ=7.78−0.64+0.77 pb. This result agrees with
predictions of the standard model.Comment: 19 pages, 6 figures, submitted to Phys. Rev.