Measurement of the tt̅ production cross section in pp̅ collisions at √s=1.96 TeV using soft electron b-tagging

Abstract

We present a measurement of the top-quark pair-production cross section in pp̅ 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 tt̅ events in the lepton+jets channel, consisting of eν+jets and μν+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 σtt̅ =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 tt̅ cross section with soft electron tags in run II of the Tevatron.