  We report a new measurement of the ttbar production cross section in pbarp
collisions at a center-of-mass energy of 1.96 TeV using events with one charged
lepton (electron or muon), missing transverse energy, and jets. Using 425
pb^{-1} of data collected using the D0 detector at the Fermilab Tevatron
Collider, and enhancing the ttbar content of the sample by tagging b jets with
a secondary vertex tagging algorithm, the ttbar production cross section is
measured to be: 6.6 \pm 0.9 (stat+syst) \pm 0.4 (lum) pb. This cross section is
the most precise D0 measurement to date for ttbar production and is in good
agreement with standard model expectations.
