Measurement of the t(t)over-bar production cross section in p(p)over-bar collisions at root s=1.96 TeV using soft electron b-tagging

We present a measurement of the top-quark pair-production cross section in 𝑝⁢(bar)𝑝 collisions at √𝑠 =1.96  TeV using a data sample corresponding to 1.7  fb−1 of integrated luminosity collected with the Collider Detector at Fermilab. We reconstruct 𝑡⁢(bar)𝑡 events in the lepton+jets channel, consisting of 𝑒⁢𝜈 +jets and 𝜇⁢𝜈 +jets final states. The dominant background is the production of 𝑊 bosons in association with multiple jets. To suppress this background, we identify electrons from the semileptonic decay of heavy-flavor jets (“soft electron tags”). From a sample of 2196 candidate events, we obtain 120 tagged events with a background expectation of 51 ±3 events, corresponding to a cross section of 𝜎_𝑡⁢(bar)𝑡 =7.8 ±2.4⁢(stat) ±1.6⁢(syst) ±0.5⁢(lumi)  pb. We assume a top-quark mass of 175  GeV/𝑐2. This is the first measurement of the 𝑡⁢(bar)𝑡 cross section with soft electron tags in run II of the Tevatron.