Measurement of the $t\bar t$ Production Cross Section in $p\bar p $ Collisions at $\sqrt{s}=1.96$ TeV Using Lepton Plus Jets Events with Soft Muon b-Tagging

We present a measurement of the $t\bar t$ production cross section in $\sim 200 \mathrm{pb^{-1}}$ of CDF Run 2 data using events with a high transverse momentum electron or muon, 3 or more jets, and missing $E_T$. Events consistent with $t\bar t$ decay are found by identifying jets containing candidate heavy- flavor semileptonic decays to muons. Backgrounds are computed from a combination of Run 2 data and simulation. Signal acceptance is determined from Run 2 $t \bar t$ PYTHIA Monte Carlo. Based on 20 candidate events with 3 or more jets and an expected background of 9.6 events, a production cross section of $5.2^{+2.9~+1.3}_{-1.9~-1.0}~\mathrm{pb}$ is measured.