Measurement of the tt Production Cross Section in pp Collisions at {radical}(s)=1.96 TeV

We measure the tt production cross section in pp collisions at {radical}(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{sup -1} of data collected by the D0 detector at the Fermilab Tevatron Collider, we measure {sigma}{sub tt}=7.62{+-}0.85 pb, assuming the current world average m{sub 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.