51ÁÔÆæÈë¿Ú

Abstract:

We present the results of a search for the top quark in 19.3 pb-1 of p̄p collisions at s =1.8 TeV. The data were collected at the Fermilab Tevatron collider using the Collider Detector at Fermilab (CDF). The search includes standard model tt̄ decays to final states eeνν̄, eμνν̄, and μμνν̄ as well as e+ν+jets or μ+ν+jets. In the (e,μ)+ν+jets channel we search for b quarks from t decays via secondary vertex identification and via semileptonic decays of the b and cascade c quarks. In the dilepton final states we find two events with a background of 0.56-0.13+0.25 events. In the e,μ+ν+jets channel with a b identified via a secondary vertex, we find six events with a background of 2.3±0.3. With a b identified via a semileptonic decay, we find seven events with a background of 3.1±0.3. The secondary vertex and semileptonic-decay samples have three events in common. The probability that the observed yield is consistent with the background is estimated to be 0.26%. The statistics are too limited to firmly establish the existence of the top quark; however, a natural interpretation of the excess is that it is due to tt̄ production. We present several cross-checks. Some support this hypothesis; others do not. Under the assumption that the excess yield over background is due to tt̄, constrained fitting on a subset of the events yields a mass of 174±10-12+13 GeV/c2 for the top quark. The tt̄ cross section, using this top quark mass to compute the acceptance, is measured to be 13.9-4.8+6.1 pb.

Abstract:

We summarize a search for the top quark with the Collider Detector at Fermilab (CDF) in a sample of p̄p collisions at s =1.8 TeV with an integrated luminosity of 19.3 pb-1. We find 12 events consistent with either two W bosons, or a W boson and at least one b jet. The probability that the measured yield is consistent with the background is 0.26%. Though the statistics are too limited to establish firmly the existence of the top quark, a natural interpretation of the excess is that it is due to tt̄ production. Under this assumption, constrained fits to individual events yield a top quark mass of 174±10-12+13 GeV/c2. The tt̄ production cross section is measured to be 13.9-4.8+6.1 pb. © 1994 The American Physical Society.

Abstract:

A prompt photon cross section measurement from the Collider Detector at Fermilab experiment is presented. Detector and trigger upgrades, as well as 6 times the integrated luminosity compared with our previous publication, have contributed to a much more precise measurement and extended PT range. As before, QCD calculations agree qualitatively with the measured cross section, but the data has a steeper slope than the calculations. © 1994 The American Physical Society.

Abstract:

We present the results of a search in p̄p collisions at s=1.8 TeV for the top quark decaying to a charged Higgs boson (H±). We search for dilepton final states from the decay chain tt̄→HH (or HW, or WW) + bb̄→ll+X. In a sample of 19.3 pb-1 collected during 1992-93 with the Collider Detector at Fermilab, we observe 2 events with a background estimation of 3.0 ± 1.0 events. Limits at 95% C.L. in the (Mtop,MH±) plane are presented. For the case Mtop