Measurement of the Top Pair Production Cross Section in Lepton+Jets Final States at D\O\ Using Lifetime b-Tagging

Measurement of the top quark pair ($t\bar{t}$) production cross section at hadron colliders can be used to test perturbative QCD predictions. Within the Standard Model, the top quark almost always decays to a $W$~boson and a $b$~quark. We present a measurement of the $t\bar{t}$ production cross section at $\sqrt{s}=1.96$ TeV in $p\bar{p}$ collisions using approximately 230 pb$^{-1}$ of data collected by the D\O\ experiment during Run II of the Fermilab Tevatron collider. The $t\bar{t}$ production cross section is measured in lepton+jets final states based on the application of two different lifetime-tagging techniques.