Top quark search with the D0 1992–1993 data sample

We present results on the search for the top quark in pp{} collisions at {}s =1.8 TeV with an integrated luminosity of 13.5±{}1.6 pb^-1. We have considered tt{} production in the standard model using electron and muon dilepton decay channels (tt{}{→}e{μ}+jets, ee+jets, and {μ}{μ}+jets) and single-lepton decay channels (tt{}{→}e+jets and {μ}+jets) with and without tagging of b quark jets. An analysis of these data optimized for top quark masses below 140 GeV/c² gives a lower top quark mass limit of 128 GeV/c². An analysis optimized for higher top quark masses yields 9 events with an expected background of 3.8±{}0.9. If we assume that the excess is due to tt{} production, and assuming a top quark mass of 180 GeV/c², we obtain a cross section of 8.2±{}5.1 pb.