  We measure the ttbar production cross section in ppbar collisions at
sqrt{s}=1.96 TeV in the lepton+jets channel. Two complementary methods
discriminate between signal and background, b-tagging and a kinematic
likelihood discriminant. Based on 0.9 fb-1 of data collected by the D0 detector
at the Fermilab Tevatron Collider, we measure sigma_ttbar=7.62+/-0.85 pb,
assuming the current world average m_t=172.6 GeV. We compare our cross section
measurement with theory predictions to determine a value for the top quark mass
of 170+/-7 GeV.

High Energy Physics - Experiment