We present the results of a search for the top quark in 19.3 ${\mathrm{pb}}^{\mathrm{-}1}$ of p¯p 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 tt¯ decays to final states eeνν¯, eμνν¯, and μμνν¯ 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.${56}_{\mathrm{-}0.13}^{+0.25\mathrm{}}$ 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 tt¯ 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 tt¯, constrained fitting on a subset of the events yields a mass of 174±${10}_{\mathrm{-}12}^{+13\mathrm{}}$ GeV/${\mathit{c}}^2$ for the top quark. The tt¯ cross section, using this top quark mass to compute the acceptance, is measured to be 13.$9_{\mathrm{-}4.8}^{+6.1\mathrm{}}$ pb.

We summarize a search for the top quark with the Collider Detector at Fermilab (CDF) in a sample of p¯p collisions at √s =1.8 TeV with an integrated luminosity of 19.3 ${\mathrm{pb}}^{\mathrm{-}1}$. 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 tt¯ production. Under this assumption, constrained fits to individual events yield a top quark mass of 174±${10}_{\mathrm{-}12}^{+13\mathrm{}}$ GeV/${\mathit{c}}^2$. The tt¯ production cross section is measured to be 13.$9_{\mathrm{-}4.8}^{+6.1\mathrm{}}$ pb.

The production and event topology of three-jet events produced in $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{}$ TeV have been studied with the Collider Detector at Fermilab at the Tevatron Collider. The distributions of the three-jet angular variables (${\psi }^{*}$ and $cos{\theta }^{*}$) and of the variables describing the energy sharing between jets ($x_3$ and $x_4$) are found to agree well with tree-level QCD calculations. These distributions are predicted to have different shapes for different initial-state subprocesses (quark-antiquark, quark-gluon, and gluon-gluon). The data are consistent with the small expected contribution from quark-antiquark initial states, in agreement with theoretical expectations.

Kinematic properties of four-jet events produced in $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{}$ TeV have been studied using data with an integrated luminosity of 325 ${\mathrm{nb}}^{-1\mathrm{}}$ collected using the Collider Detector at Fermilab during the 1988-1989 Fermilab Collider run. The individual jet $p_T$ spectra and the angles between each jet pair are compared to the predictions of leading-order quantum chromodynamics for the double gluon bremsstrahlung process and good agreement is observed. In addition, a search for double parton scattering has been undertaken using variables sensitive to the topology of four-jet events. A small double parton content provides the best description of the data. We find $\frac{N_{\mathrm{DP}}}{N_{\mathrm{DB}}}={5.4}_{-2.0\mathrm{}}^{+1.6\mathrm{}}\%$, where $N$ represents the number of events attributed to each process. We measure ${\sigma }_{\mathrm{DP}}={63}_{-28\mathrm{}}^{+32\mathrm{}}$ nb for jets having $p_T>25\mathrm{}$ GeV/c in the pseudorapidity interval $\left|\eta \right|<\mathrm{}3.5\mathrm{}$.

Inclusive J/ψ and ψ(2S) production has been studied in p¯p collisions at √s =1.8 TeV using 2.6±0.2 ${\mathrm{pb}}^{\mathrm{-}1}$ of data taken with the Collider Detector at Fermilab. The products of production cross section times branching fraction were measured as functions of ${\mathit{P}}_{\mathit{T}}$ for J/ψ→${\mathrm{\mu }}^{+}$ ${\mathrm{\mu }}^{\mathrm{-}}$ and ψ(2S)→${\mathrm{\mu }}^{+}$ ${\mathrm{\mu }}^{\mathrm{-}}$. In the kinematic range ${\mathit{P}}_{\mathit{T}}$>6 GeV/c and ‖η‖≤0.5 we get σ(p¯p→J/ψ X)B(J/ψ→${\mathrm{\mu }}^{+}$ ${\mathrm{\mu }}^{\mathrm{-}}$) =6.88±0.23(stat${)}_{\mathrm{-}1.08}^{+0.93\mathrm{}}$(syst) nb, and σ(p¯p→ψ(2S)X)B(ψ(2S)→${\mathrm{\mu }}^{+}$ ${\mathrm{\mu }}^{\mathrm{-}}$) =0.232±0.051(stat${)}_{\mathrm{-}0.032}^{+0.029\mathrm{}}$(syst)nb. From these values we calculate the inclusive b-quark production cross section.