Observation of top quarks in the dilepton decay channel t(anti t) (yields) e((mu))(upsilon)(sub e((mu))) (tau)(upsilon)(sub (tau)) b(anti b) using hadronic tau decays at CDF

摘要

We present a search for dilepton events from top decays with one electron or muon and a hadronically decaying (tau) lepton. The total acceptance x efficiency is (O.119 (+-) 0.014((ital stat)))% for (ital m(sub top)) = 175 GeV. In 110 pb(sup -1) of data we expect 1.1 (+-) 0. 3((ital stat)) signal events and a total background of 1.96 (+-) 0.35((ital stat)) events while observing 4 candidate events (2 (ital e)(tau) and 2 (mu)(tau)). Three events are (ital b)-tagged. If a tag is required, the probability for the estimated background (0.225 (+-) 0.011 events) to fluctuate to (>=) 3 events is 0.13% (3.0 (sigma)). A first measurement of the (ital t(anti t)) production cross section based on these events yields (sigma)(sub t(anti t)) = 15.6(sup +18. 6)(sub -13.2)((ital stat)) pb.