S. Belforte

We establish the existence of the top quark using a 67 pb^-1 data sample of Pbar-P collisions at Sqrt(s) = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). Employing techniques similar to those we previously published, we observe a signal consistent with t-tbar decay to WW b-bbar, but inconsistent with the background prediction by 4.8 sigma. Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. We measure the top quark mass to be 176 +/-8(stat) +/- 10(sys.) GeV/c^2, and the t-tbar production cross section to be 6.8 +3.6 -2.4 pb.

We present a new measurement of the inclusive and differential production cross sections of $J/\psi$ mesons and $b$-hadrons in proton-antiproton collisions at $\sqrt{s}=1960$ GeV. The data correspond to an integrated luminosity of 39.7 pb$^{-1}$ collected by the CDF Run II detector. We find the integrated cross section for inclusive $J/\psi$ production for all transverse momenta from 0 to 20 GeV/$c$ in the rapidity range $|y|<0.6$ to be $4.08 \pm 0.02 (stat)^{+0.36}_{-0.33} (syst) \mu {\rm b}$. We separate the fraction of $J/\psi$ events from the decay of the long-lived $b$-hadrons using the lifetime distribution in all events with $p_T(J/\psi) > 1.25$ GeV/$c$. We find the total cross section for $b$-hadrons, including both hadrons and anti-hadrons, decaying to $J/\psi$ with transverse momenta greater than 1.25 GeV/$c$ in the rapidity range $|y(J/\psi)|<0.6$, is $ 0.330 \pm 0.005 (stat) ^{+0.036}_{-0.033} (syst) ~\mu{\rm b}$. Using a Monte Carlo simulation of the decay kinematics of $b$-hadrons to all final states containing a $J/\psi$, we extract the first measurement of the total single $b$-hadron cross section down to zero transverse momentum at $\sqrt{s}=1960$ GeV. We find the total single $b$-hadron cross section integrated over all transverse momenta for $b$-hadrons in the rapidity range $|y|<0.6$ to be $ 17.6 \pm 0.4 (stat)^{+2.5}_{-2.3} (syst) \mu{\rm b}$.

We report the observation of a narrow state decaying into $J/\ensuremath{\psi}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and produced in $220\text{ }{\mathrm{p}\mathrm{b}}^{\ensuremath{-}1}$ of $\stackrel{\ifmmode \bar{}\else \={}\fi{}}{p}p$ collisions at $\sqrt{s}=1.96\text{ }\mathrm{T}\mathrm{e}\mathrm{V}$ in the CDF II experiment. We observe $730\ifmmode\pm\else\textpm\fi{}90$ decays. The mass is measured to be $3871.3\ifmmode\pm\else\textpm\fi{}0.7(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t})\ifmmode\pm\else\textpm\fi{}0.4(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})\text{ }\mathrm{M}\mathrm{e}\mathrm{V}/{c}^{2}$, with an observed width consistent with the detector resolution. This is in agreement with the recent observation by the Belle Collaboration of the $X(3872)$ meson.

The Collider Detector at Fermilab (CDF) is a 5000 t magnetic detector built to study 2 TeV pp collisions at the Fermilab Tevatron. Event analysis is based on charged particle tracking, magnetic momentum analysis and fine-grained calorimetry. The combined electromagnetic and hadron calorimetry has approximately uniform granularity in rapidity-azimuthal angle and extends down to 2° from the beam direction. Various tracking chambers cover the calorimeter acceptance and extend charged particle tracking down to 2 mrad from the beam direction. Charged particle momenta are analyzed in a 1.5 T solenoidal magnetic field, generated by a superconducting coil which is 3 m in diameter and 5 m in length. The central tracking chamber measures particle momenta with a resolution better then δpT/pT2 = 2 × 10−3 (GeV/c)−1 in the region 40° < θ < 140° and δPT/pT2 ≤ 4 × 10−3 for 21° < θ < 40° and 140° < θ < 159°. The calorimetry, which has polar angle coverage from 2° to 178° and full azimuthal coverage, consists of electromagnetic shower counters and hadron calorimeters, and is segmented into about 5000 projective “towers” or solid angle elements. Muon coverage is provided by drift chambers in the region 56° < θ < 124°, and by large forward toroid systems in the range 3° < θ < 16° and 164° < θ < 177°. Isolated high momentum muons can be identified in the intermediate angular range by a comparison of the tracking and calorimeter information in many cases. A custom front-end electronics system followed by a large Fastbus network provides the readout of the approximately 100 000 detector channels. Fast Level 1 and Level 2 triggers make a detailed pre-analysis of calorimetry and tracking information; a Level 3 system of on-line processors will do parallel processing of events. This paper provides a summary of the aspects of the detector which are relevant to its physics capabilities, with references to more detailed descriptions of the subsystems.

We present the results of a search for the top quark in 19.3 pb−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+0.25−0.13 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+13−12 GeV/c2 for the top quark. The tt¯ cross section, using this top quark mass to compute the acceptance, is measured to be 13.9+6.1−4.8 pb.Received 25 April 1994DOI:https://doi.org/10.1103/PhysRevD.50.2966©1994 American Physical Society

We summarize a search for the top quark with the Collider Detector at Fermilab (CDF) in a sample of $\bar{p}p$ collisions at $\sqrt{s}$= 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 $t\bar{t}$ production. Under this assumption, constrained fits to individual events yield a top quark mass of $174 \pm 10^{+13}_{-12}$ GeV/c$^2$. The $t\bar{t}$ production cross section is measured to be $13.9^{+6.1}_{-4.8}$~pb. (Submitted to Physical Review Letters on May 16, 1994).

We report the observation of B0s−¯¯¯B0s oscillations from a time-dependent measurement of the B0s−¯¯¯B0s oscillation frequency Δms. Using a data sample of 1 fb−1 of p¯p collisions at √s=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron, we find signals of 5600 fully reconstructed hadronic Bs decays, 3100 partially reconstructed hadronic Bs decays, and 61 500 partially reconstructed semileptonic Bs decays. We measure the probability as a function of proper decay time that the Bs decays with the same, or opposite, flavor as the flavor at production, and we find a signal for B0s−¯¯¯B0s oscillations. The probability that random fluctuations could produce a comparable signal is 8×10−8, which exceeds 5σ significance. We measure Δms=17.77±0.10(stat)±0.07(syst) ps−1 and extract |Vtd/Vts|=0.2060±0.0007(Δms)+0.0081−0.0060(Δmd+theor).Received 18 September 2006DOI:https://doi.org/10.1103/PhysRevLett.97.242003©2006 American Physical Society

Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for the HL-LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that the efforts complement each other. In this spirit, this white paper describes the R&D activities required to prepare for this software upgrade.

We present a study of J/ψ and ψ(2S) production in p¯p collisions, at √s=1.8TeV with the CDF detector at Fermilab. The J/ψ and ψ(2S) mesons are reconstructed using their μ+μ− decay modes. We have measured the inclusive production cross section for both mesons as a function of their transverse momentum in the central region, |η|<0.6. We also measure the fraction of these events originating from b hadrons. We thus extract individual cross sections for J/ψ and ψ(2S) mesons from b-quark decays and prompt production. We find a large excess (approximately a factor of 50) of direct ψ(2S) production compared with predictions from the color singlet model.Received 3 February 1997DOI:https://doi.org/10.1103/PhysRevLett.79.572©1997 American Physical Society

We have observed bottom-charm mesons B_c via the decay mode Bc -&gt; J/psi lepton neutrino in 1.8 TeV p-bar p collisions using the CDF detector at the Fermilab Tevatron. A fit of background and signal contributions to the J/psi + lepton mass distribution yielded 20.4 +6.2 -5.5 events from B_c mesons. A fit to the same distribution with background alone was rejected at the level of 4.8 standard deviations. We measured the B_c mass to be 6.40 +- 0.39 +- 0.13 GeVc^2 and the B_c lifetime to be tau(B_c) = 0.46 +0.18 -0.16 +- 0.03 ps. We measured the production cross section times branching ratio for B_c -&gt; J/psi lepton neutrino relative to that for B+ -&gt; J/psi K to be 0.132 +0.041 -0.037 (stat) +- 0.031 (syst) +0.032 -0.020 (lifetime).

The production and event topology of three-jet events produced in p¯p collisions at √s=1.8 TeV have been studied with the Collider Detector at Fermilab at the Tevatron Collider. The distributions of the three-jet angular variables (ψ∗ and cosθ∗) and of the variables describing the energy sharing between jets (x3 and x4) 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.Received 3 September 1991DOI:https://doi.org/10.1103/PhysRevD.45.1448©1992 American Physical Society

We present a measurement of the $t\overline{t}$ production cross section using events with one charged lepton and jets from $p\overline{p}$ collisions at a center-of-mass energy of 1.96 TeV. In these events, heavy flavor quarks from top quark decay are identified with a secondary vertex tagging algorithm. From $162\text{ }\text{ }\mathrm{p}{\mathrm{b}}^{\ensuremath{-}1}$ of data collected by the Collider Detector at Fermilab, a total of 48 candidate events are selected, where $13.5\ifmmode\pm\else\textpm\fi{}1.8$ events are expected from background contributions. We measure a $t\overline{t}$ production cross section of ${5.6}_{\ensuremath{-}1.1}^{+1.2}(\mathrm{stat}.{)}_{\ensuremath{-}0.6}^{+0.9}(\mathrm{syst}.)\text{ }\text{ }\mathrm{pb}$.

A strong signal for double parton (DP) scattering is observed in a $16{\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ sample of $\overline{p}p\ensuremath{\rightarrow}\ensuremath{\gamma}/{\ensuremath{\pi}}^{0}+3\mathrm{jets}+X$ data from the CDF experiment at the Fermilab Tevatron. In DP events, two separate hard scatterings take place in a single $\overline{p}p$ collision. We isolate a large sample of data $(\ensuremath{\sim}14000\mathrm{events})$ of which 53% are found to be DP. The process-independent parameter of double parton scattering, ${\ensuremath{\sigma}}_{\mathrm{eff}},$ is obtained without reference to theoretical calculations by comparing observed DP events to events with hard scatterings in separate $\overline{p}p$ collisions. The result ${\ensuremath{\sigma}}_{\mathrm{eff}}=(14.5\ifmmode\pm\else\textpm\fi{}{1.7}_{\ensuremath{-}2.3}^{+1.7})\mathrm{mb}$ represents a significant improvement over previous measurements, and is used to constrain simple models of parton spatial density. The Feynman $x$ dependence of ${\ensuremath{\sigma}}_{\mathrm{eff}}$ is investigated and none is apparent. Further, no evidence is found for kinematic correlations between the two scatterings in DP events.

Inclusive J/\ensuremath{\psi} and \ensuremath{\psi}(2S) production has been studied in p\ifmmode\bar\else\textasciimacron\fi{}p collisions at \ensuremath{\surd}s =1.8 TeV using 2.6\ifmmode\pm\else\textpm\fi{}0.2 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ 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/\ensuremath{\psi}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$ and \ensuremath{\psi}(2S)\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$. In the kinematic range ${\mathit{P}}_{\mathit{T}}$&gt;6 GeV/c and \ensuremath{\Vert}\ensuremath{\eta}\ensuremath{\Vert}\ensuremath{\le}0.5 we get \ensuremath{\sigma}(p\ifmmode\bar\else\textasciimacron\fi{}p\ensuremath{\rightarrow}J/\ensuremath{\psi} X)B(J/\ensuremath{\psi}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$) =6.88\ifmmode\pm\else\textpm\fi{}0.23(stat${)}_{\mathrm{\ensuremath{-}}1.08}^{+0.93}$(syst) nb, and \ensuremath{\sigma}(p\ifmmode\bar\else\textasciimacron\fi{}p\ensuremath{\rightarrow}\ensuremath{\psi}(2S)X)B(\ensuremath{\psi}(2S)\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$) =0.232\ifmmode\pm\else\textpm\fi{}0.051(stat${)}_{\mathrm{\ensuremath{-}}0.032}^{+0.029}$(syst)nb. From these values we calculate the inclusive b-quark production cross section.

We have measured the fraction of $J/\ensuremath{\psi}$ mesons originating from ${\ensuremath{\chi}}_{c}$ meson decays in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$. The fraction, for ${P}_{T}^{J/\ensuremath{\psi}}&gt;4.0\mathrm{GeV}/c$ and $|{\ensuremath{\eta}}^{J/\ensuremath{\psi}}|&lt;0.6$, not including contributions from $b$ flavored hadrons, is $29.7%\ifmmode\pm\else\textpm\fi{}1.7%(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}5.7%(\mathrm{syst})$. We have determined the cross sections for $J/\ensuremath{\psi}$ mesons originating from ${\ensuremath{\chi}}_{c}$ decays and for directly produced $J/\ensuremath{\psi}$ mesons. We have found that direct $J/\ensuremath{\psi}$ production is in excess of the prediction of the color singlet model by the same factor found for direct $\ensuremath{\psi}(2S)$ production.

We report the first measurements of inclusive W and Z boson cross sections times the corresponding leptonic branching ratios for p pbar collisions at sqrt{s} = 1.96 TeV based on the decays of the W and Z bosons into electrons and muons. The data were recorded with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 72.0 +/- 4.3 pb-1. We test e-mu lepton universality in W decays by measuring the ratio of the W->mu nu to W->e nu cross sections and determine a value of 0.991 +/- 0.004(stat.) +/- 0.011(syst.) for the ratio of W-l-nu couplings (g_mu/g_e). Since there is no sign of non-universality, we combine our cross section measurements in the different lepton decay modes and obtain sigma*BR(W->lnu) = 2.749 +/- 0.010(stat.) +/- 0.053(syst.) +/- 0.165(lum.) nb and sigma*BR(gamma*/Z->ll)=254.9 +/- 3.3(stat.) +/- 4.6(syst.) +/- 15.2(lum.) pb for dilepton pairs in the mass range between 66 GeV/c^2 and 116 GeV/c^2. We compute the ratio R of the W->lnu to Z->ll cross sections taking all correlations among channels into account and obtain R=10.84 +/- 0.15(stat.) +/- 0.14(syst.) including a correction for the virtual photon exchange component in our measured gamma*/Z->ll cross section. Based on the measured value of R, we extract values for the W leptonic branching ratio, BR(W->lnu) =0.1082 +/- 0.0022; the total width of the W boson, Gamma(W) =2092 +/- 42 MeV; and the ratio of W and Z boson total widths, Gamma(W)/Gamma(Z) = 0.838 +/- 0.017. In addition, we use our extracted value of Gamma(W) whose value depends on various electroweak parameters and certain CKM matrix elements to constrain the V_CS CKM matrix element, |V_CS| = 0.976 +/- 0.030.

The inclusive jet differential cross section has been measured for jet transverse energies, ET, from 15 to 440 GeV, in the pseudorapidity region 0.1≤|η|≤0.7. The results are based on 19.5pb−1 of data collected by the CDF Collaboration at the Fermilab Tevatron collider. The data are compared with QCD predictions for various sets of parton distribution functions. The cross section for jets with ET>200GeV is significantly higher than current predictions based on O(αs3) perturbative QCD calculations. Various possible explanations for the high- ET excess are discussed.Received 25 January 1996DOI:https://doi.org/10.1103/PhysRevLett.77.438©1996 American Physical Society

We report the observation of bottom-charmed mesons ${B}_{c}$ in 1.8 TeV $p\overline{p}$ collisions using the CDF detector at the Fermilab Tevatron. The ${B}_{c}$ mesons were found through their semileptonic decays, ${B}_{c}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}J/\ensuremath{\psi}{l}^{\ifmmode\pm\else\textpm\fi{}}X.$ A fit to the $J/\ensuremath{\psi}l$ mass distribution yielded ${20.4}_{\ensuremath{-}5.5}^{+6.2}$ events from ${B}_{c}$ mesons. A test of the null hypothesis, i.e., an attempt to fit the data with background alone, was rejected at the level of 4.8 standard deviations. By studying the quality of the fit as a function of the assumed ${B}_{c}$ mass, we determined ${M(B}_{c})=6.40\ifmmode\pm\else\textpm\fi{}0.39(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.13\mathrm{}(\mathrm{syst})\mathrm{}\mathrm{GeV}{/c}^{2}.$ From the distribution of trilepton intersection points in the plane transverse to the beam direction we measured the ${B}_{c}$ lifetime to be $\ensuremath{\tau}{(B}_{c}{)=0.46}_{\ensuremath{-}0.16}^{+0.18}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.03\mathrm{}(\mathrm{syst})\mathrm{}\mathrm{ps}.$ We also measured the ratio of production cross section times branching fraction for ${B}_{c}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}{l}^{+}\ensuremath{\nu}$ relative to that for ${B}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{+}$ to be $\frac{\ensuremath{\sigma}{(B}_{c})\ifmmode\times\else\texttimes\fi{}{B(B}_{c}\ensuremath{\rightarrow}J/\ensuremath{\psi}l\ensuremath{\nu})}{\ensuremath{\sigma}(B)\ifmmode\times\else\texttimes\fi{}B(\stackrel{\ensuremath{\rightarrow}}{B}J/\ensuremath{\psi}K)}{=0.132}_{\ensuremath{-}0.037}^{+0.041}{(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.031\mathrm{}(\mathrm{syst})}_{\mathrm{\ensuremath{-}}0.020}^{+0.032}(\mathrm{lifetime}).$

We have measured the polarization of J/psi and psi(2S) mesons produced in pp collisions at sqrt[s] = 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992-1995. The polarization of promptly produced J/psi [psi(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4 [5.5]<P(T)<20 GeV/c and |y|<0.6. For P(T) greater than or approximately equal 12 GeV/c we do not observe significant polarization in the prompt component.

We present an analysis of angular distributions and correlations of the X(3872) particle in the exclusive decay mode X(3872)->J/psi pi+ pi- with J/psi->mu+ mu-. We use 780 pb -1 of data from ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We derive constraints on spin, parity, and charge conjugation parity of the X(3872) particle by comparing measured angular distributions of the decay products with predictions for different JPC hypotheses. The assignments JPC = 1++ and 2-+ are the only ones consistent with the data.

We present measurements of the pseudorapidity (η) distribution of charged particles (dNchdη) produced within |η|≤3.5 in proton-antiproton collisions at √s of 630 and 1800 GeV. We measure dNchdη at η=0 to be 3.18±0.06(stat)±0.10(syst) at 630 GeV, and 3.95±0.03 (stat)±0.13(syst) at 1800 GeV. Many systematic errors in the ratio of dNchdη at the two energies cancel, and we measure 1.26±0.01±0.04 for the ratio of dNchdη at 1800 GeV to that at 630 GeV within |η|≤3. Comparing to lower-energy data, we observe an increase faster than ln(s) in dNchdη at η=0.Received 2 October 1989DOI:https://doi.org/10.1103/PhysRevD.41.2330©1990 American Physical Society

Measurements of inclusive transverse-momentum spectra for charged particles produced in proton-antiproton collisions at \ensuremath{\surd}2 of 630 and 1800 GeV are presented and compared with data taken at lower energies.

We report a measurement of the proton-antiproton total cross section, VT, at c.m.s.energies fi = 546 and .I800 GeV.Using the luminosity'independent method, we find Q=61.26&0.93 mb at ,/k546GeV and 80.03f2.24mb at fi = 1800 GeV.In this energy range, the ratio v,l/UT increases from 0.2lOkO.002to 0.246~0.004.

The growth and development of ``charged particle jets'' produced in proton-antiproton collisions at $1.8 \mathrm{TeV} $ are studied over a transverse momentum range from $0.5$ $\mathrm{GeV}/c$ to $50$ $\mathrm{GeV}/c.$ A variety of leading (highest transverse momentum) charged jet observables are compared with the QCD Monte Carlo models HERWIG, ISAJET, and PYTHIA. The models describe fairly well the multiplicity distribution of charged particles within the leading charged jet, the size of the leading charged jet, the radial distribution of charged particles and transverse momentum around the leading charged jet direction, and the momentum distribution of charged particles within the leading charged jet. The direction of the leading ``charged particle jet'' in each event is used to define three regions of $\ensuremath{\eta}\ensuremath{-}\ensuremath{\varphi}$ space. The ``toward'' region contains the leading ``charged particle jet,'' while the ``away'' region, on the average, contains the away-side jet. The ``transverse'' region is perpendicular to the plane of the hard $2$-to-$2$ scattering and is very sensitive to the ``underlying event'' component of the QCD Monte Carlo models. HERWIG, ISAJET, and PYTHIA with their default parameters do not describe correctly all the properties of the ``transverse'' region.

We present the first measurement of the Bs-Bsbar oscillation frequency Delta m_s. We use 1 fb^-1 of data from p-pbar collisions at sqrt{s}=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. The sample contains signals of 3,600 fully reconstructed hadronic Bs decays and 37,000 partially reconstructed semileptonic Bs decays. We measure the probability as a function of proper decay time that the Bs decays with the same, or opposite, flavor as the flavor at production, and we find a signal consistent with Bs-Bsbar oscillations. The probability that random fluctuations could produce a comparable signal is 0.2%. Under the hypothesis that the signal is due to Bs-Bsbar oscillations, we measure Delta m_s = 17.31^{+0.33}_{-0.18} (stat.) +- 0.07 (syst.) ps^-1 and determine |Vtd/Vts| = 0.208^{+0.001}_{-0.002} (exp.) ^{+0.008}_{-0.006} (theo.).

The CDF central and endwall hadron calorimeter covers the polar region between 30° and 150° and a full 2π in azimuth. It consists of 48 steel-scintillator central modules with 2.5 cm sampling and 48 steel-scintillator endwall modules with 5.0 cm sampling. A general description of the detector is given. Calibration techniques and performance are discussed. Some results of the test beam studies are shown.

Kinematic properties of four-jet events produced in p¯p collisions at √s=1.8 TeV have been studied using data with an integrated luminosity of 325 nb−1 collected using the Collider Detector at Fermilab during the 1988-1989 Fermilab Collider run. The individual jet pT 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 NDPNDB=5.4+1.6−2.0%, where N represents the number of events attributed to each process. We measure σDP=63+32−28 nb for jets having pT>25 GeV/c in the pseudorapidity interval |η|<3.5.Received 11 January 1993DOI:https://doi.org/10.1103/PhysRevD.47.4857©1993 American Physical Society

We report on measurements of differential cross sections dsigma/dp(T) for prompt charm meson production in ppmacr; collisions at sqrt[s]=1.96 TeV using 5.8+/-0.3 pb(-1) of data from the CDF II detector at the Fermilab Tevatron. The data are collected with a new trigger that is sensitive to the long lifetime of hadrons containing heavy flavor. The charm meson cross sections are measured in the central rapidity region |y|</=1 in four fully reconstructed decay modes: D0-->K-pi(+), D(*+)-->D0pi(+), D+-->K-pi(+)pi(+), D(+)(s)-->phipi(+), and their charge conjugates. The measured cross sections are compared to theoretical calculations.

A search for the top quark in p\ifmmode\bar\else\textasciimacron\fi{}p collisions at a center-of-mass energy of 1.8 TeV using the Collider Detector at Fermilab is described. A study of events selected by requiring an energetic electron, missing transverse energy, and two or more jets excludes at 95% confidence level the standard-model production and decay of tt\ifmmode\bar\else\textasciimacron\fi{} pairs if the top-quark mass is between 40 and 77 GeV/${c}^{2}$. The observed electron + multijet data are consistent with W-boson production.

We have searched for heavy neutral gauge bosons (Z′) in dielectron and dimuon decay modes using 110pb−1 of ¯pp collisions at √s=1.8TeV collected with the Collider Detector at Fermilab. We present a limit on the production cross section times branching ratio of a Z′ boson decaying into dileptons as a function of Z′ mass. For mass MZ′>600GeV/c2, the upper limit is 40 fb at 95% confidence level. We set the lower mass limits of 690, 590, 620, 595, 565, 630, and 600GeV/c2 for Z′SM, Zψ, Zη, Zχ, ZI, ZLR, and ZALRM, respectively.Received 6 May 1997DOI:https://doi.org/10.1103/PhysRevLett.79.2192©1997 American Physical Society

We have analyzed events with jets and large missing transverse energy produced in p\ifmmode\bar\else\textasciimacron\fi{}p colisions at \ensuremath{\surd}s =1.8 TeV. The observed event rate is consistent with standard model predictions. In a version of the supersymmetry (SUSY) model with a light photino (${\mathit{m}}_{\ensuremath{\gamma}}$\ifmmode \tilde{}\else \~{}\fi{}15 GeV/${\mathit{c}}^{2}$) and no cascade decays, we exclude at the 90% confidence level the existence of squarks and gluinos with masses less than 126 and 141 GeV/${\mathit{c}}^{2}$, respectively. The mass limits are lower with other choices of the SUSY parameters. An example is presented.

The Collider Detector at Fermilab (CDF) experiment's Silicon Vertex Trigger (SVT) is a system of 150 custom 9U VME boards that reconstructs axial tracks in the CDF silicon strip detector in a 15μs pipeline. SVT's 35μm impact parameter resolution enables CDF's Level 2 trigger to distinguish primary and secondary particles, and hence to collect large samples of hadronic bottom and charm decays. We review some of SVT's key design features. Speed is achieved with custom VLSI pattern recognition, linearized track fitting, pipelining, and parallel processing. Testing and reliability are aided by built-in logic state analysis and test-data sourcing at each board's input and output, a common interboard data link, and a universal “Merger” board for data fan-in/fan-out. Speed and adaptability are enhanced by use of modern FPGAs.

We report on measurements of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) differential cross sections (d(2)sigma/dp(T)dy)(/y/<0.4), as well as on the Upsilon(1S) polarization in p p macro collisions at square root of s = 1.8 TeV using a sample of 77+/-3 pb(-1) collected by the collider detector at Fermilab. The three resonances were reconstructed through the decay Upsilon-->mu(+)mu(-). The measured angular distribution of the muons in the Upsilon(1S) rest frame is consistent with unpolarized meson production.

We present results from searches for the top quark pp\ifmmode\bar\else\textasciimacron\fi{} collisions at the Fermilab Tevatron Collider. The data sample was collected during 1988--89 with the Collider Detector at Fermilab and has an integrated luminosity of 4.1 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$. Our previous search for e\ensuremath{\mu} final states for tt\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}e\ensuremath{\nu}b \ensuremath{\mu}\ensuremath{\nu}b\ifmmode\bar\else\textasciimacron\fi{} decays has been extended to include the ee and \ensuremath{\mu}\ensuremath{\mu} channels. In addition, we have searched in each event with a high-transverse-momentum lepton accompanied by hadron jets for a low-transverse-momentum muon as a tag of a bottom quark in tt\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}l\ensuremath{\nu}bqq\ifmmode\bar\else\textasciimacron\fi{}b\ifmmode\bar\else\textasciimacron\fi{} decays. A lower limit on the top-quark mass of 91 GeV/${\mathit{c}}^{2}$ is obtained at the 95% confidence level, assuming standard model decays.

This article presents a measurement of the top quark mass using the CDF II detector at Fermilab. Colliding beams of protons and anti-protons at Fermilab's Tevatron (sqrt{s}=1.96 TeV) produce top/anti-top pairs, which decay to W^+W^-bbbar; events are selected where one W decays to hadrons, and one W decays to either e or mu plus a neutrino. The data sample corresponds to an integrated luminosity of approximately 318 pb^-1. A total of 165 ttbar events are separated into four subsamples based on jet transverse energy thresholds and the number of b jets identified by reconstructing a displaced vertex. In each event, the reconstructed top quark invariant mass is determined by minimizing a chi-squared for the overconstrained kinematic system. At the same time, the mass of the hadronically decaying W boson is measured in the same event sample. The observed W boson mass provides an in situ improvement in the determination of the hadronic jet energy scale, JES. A simultaneous likelihood fit of the reconstructed top quark masses and the W boson invariant masses in the data sample to distributions from simulated signal and background events gives a top quark mass of 173.5 +3.7/-3.6 (stat.+JES) +/- 1.3 (other syst.) GeV/c^2, or 173.5 +3.9/-3.8 GeV/c^2.

We have determined mW=79.91±0.39 GeV/c2 from an analysis of W→eν and W→μν data from the Collider Detector at Fermilab in p¯p collisions at a c.m. energy of √s =1.8 TeV. This result, together with the world-average Z mass, determines the weak mixing angle to be sin2θW=0.232±0.008. Bounds on the top-quark mass are discussed.Received 13 August 1990DOI:https://doi.org/10.1103/PhysRevLett.65.2243©1990 American Physical Society

Antiproton-proton elastic scattering was measured at c.m.s. energies √s =546 and 1800 GeV in the range of four-momentum transfer squared 0.025<-t<0.29 GeV2. The data are well described by the exponential form ebt with a slope b=15.28±0.58 (16.98±0.25) GeV−2 at √s =546 (1800) GeV. The elastic scattering cross sections are, respectively, σel=12.87±0.30 and 19.70±0.85 mb.Received 5 August 1993DOI:https://doi.org/10.1103/PhysRevD.50.5518©1994 American Physical Society

We search for the flavor-changing neutral current decays of the top quark t→qγ and t→qZ (here q represents the c and u quarks) in ¯pp collisions at √s=1.8TeV. We use a dataset (∫Ldt∼110pb−1) collected during the 1992–1995 run of the Collider Detector at Fermilab. We set 95% confidence level limits on the branching fractions B(t→qγ)<3.2% and B(t→qZ)<33%, consistent with the standard model.Received 24 July 1997DOI:https://doi.org/10.1103/PhysRevLett.80.2525©1998 American Physical Society

We report on measurements of the inclusive jet production cross section as a function of the jet transverse momentum in pp¯ collisions at s=1.96 TeV, using the kT algorithm and a data sample corresponding to 1.0 fb−1 collected with the Collider Detector at Fermilab in run II. The measurements are carried out in five different jet rapidity regions with |yjet|<2.1 and transverse momentum in the range 54<pTjet<700 GeV/c. Next-to-leading order perturbative QCD predictions are in good agreement with the measured cross sections.4 MoreReceived 29 January 2007Publisher error corrected 25 May 2007DOI:https://doi.org/10.1103/PhysRevD.75.092006©2007 American Physical Society

The transverse momentum and total cross section of e^+e^- pairs in the Z-boson region of 66<M_{ee}<116 GeV$/c^2$ from $p\bar{p}$ collisions at $\sqrt{s}=1.8$ TeV are measured using 110 pb^{-1} of collisions taken by the Collider Detector at Fermilab during 1992-1995. The total cross section is measured to be $248 \pm 11$ pb. The differential transverse momentum cross section is compared with calculations that match quantum chromodynamics perturbation theory at high transverse momentum with the gluon resummation formalism at low transverse momentum.

This paper presents the first direct measurement of the $B$ meson differential cross section, $d\sigma/dp_T$, in $p\bar{p}$ collisions at $\sqrt{s}=1.8$ TeV using a sample of $19.3 \pm 0.7$ pb$^{-1}$ accumulated by the Collider Detector at Fermilab (CDF). The cross section is measured in the central rapidity region $|y| < 1$ for $p_T(B) > 6.0$ GeV/$c$ by fully reconstructing the $B$ meson decays $B^{+}\to J/\psi K^{+}$ and $B^{0}\to J/\psi K^{*0}(892)$, where $J/\psi \to \mu^+\mu^-$ and $K^{*0} \to K^+ \pi^-$. A comparison is made to the theoretical QCD prediction calculated at next-to-leading order.

We report the first measurements of inclusive W and Z cross sections times leptonic branching ratios for pp collisions at square root[s]=1.96 TeV, based on their decays to electrons and muons. The data correspond to an integrated luminosity of 72 pb(-1) recorded with the CDF detector at the Fermilab Tevatron. We test e-mu universality in W decays, and we measure the ratio of leptonic W and Z rates from which the leptonic branching fraction B(W-->lnu) can be extracted as well as an indirect value for the total width of the W and the Cabibbo-Kobayashi-Maskawa matrix element, |V(cs)|.

We measure the dipion mass spectrum in X(3872)--> J/psipi(+) pi(-) decays using 360 pb(-1) of pp collisions at square root s= 1.96 TeV collected with the CDF II detector. The spectrum is fit with predictions for odd C-parity ((3)S(1), (1)P(1), and (3)D(J)) charmonia decaying to J/psipi(+) pi(-), as well as even C-parity states in which the pions are from rho(0) decay. The latter case also encompasses exotic interpretations, such as a D(0)D(*0) molecule. Only the (3)S(1) and J/psirho hypotheses are compatible with our data. Since (3)S(1) is untenable on other grounds, decay via J/psirho is favored, which implies C= +1 for the X(3872). Models for J/psi - rho different angular momenta L are considered. Flexibility in the models, especially the introduction of rho - omega interference, enables good descriptions of our data for both L = 0 and 1.

We have used 106 pb^-1 of data collected with the Collider Detector at Fermilab to search for new particles decaying to dijets. We exclude at the 95% confidence level models containing the following new particles: axigluons and flavor universal colorons with mass between 200 and 980 GeV/c, excited quarks with mass between 80 and 570 GeV/c^2 and between 580 and 760 GeV/c^2, color octet technirhos with mass between 260 and 480 GeV/c^2, W' bosons with mass between 300 and 420 GeV/c^2, and E_6 diquarks with mass between 290 and 420 GeV/c^2.

An analysis of pp\ifmmode\bar\else\textasciimacron\fi{} collision events at \ensuremath{\surd}s =1.8 TeV with jets and large missing transverse energy finds no event with missing transverse energy &gt;40 GeV. This result yields a 90%-C.L. limit on the cross section for one-jet-event production of &lt;0.1 nb for events with the jet in the pseudorapidity range \ensuremath{\Vert}\ensuremath{\eta}\ensuremath{\Vert}&lt;1.0 and with jet ${E}_{T}$&gt;52 GeV. Limits on the masses of squarks and gluinos in a minimal supersymmetry model are also set. At the 90% C.L., ${m}_{q\ifmmode \tilde{}\else \~{}\fi{}}$&gt;74 GeV and ${m}_{g\ifmmode \tilde{}\else \~{}\fi{}}$&gt;73 GeV.

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.Received 26 July 1994DOI:https://doi.org/10.1103/PhysRevLett.73.2662©1994 American Physical Society

We report the results of a search for a charged Higgs boson in the decays of top quarks produced in pp collisions at a center-of-mass energy of 1.96 TeV. We use a data sample corresponding to an integrated luminosity of 193 pb-1 collected by the upgraded Collider Detector at Fermilab. No evidence for charged Higgs production is found, allowing 95% C.L. upper limits to be placed on BR(t-->H+b) for different charged Higgs decay scenarios. In addition, we present in the minimal supersymmetric standard model (mH+/-, tanbeta) plane the first exclusion regions with radiative and Yukawa coupling corrections.

We report results from a study of events with a leading antiproton of beam momentum fraction 0.905<x(F)<0.965 and 4-momentum transfer squared |t|<3 GeV2 produced in &pmacr;p collisions at sqrt[s] = 1800 GeV at the Fermilab Tevatron collider. Approximately 2% of the events contain two jets of transverse energy E(jet)(T)>7 GeV. Using the dijet events, we evaluate the diffractive structure function of the antiproton and compare it with expectations based on results obtained in diffractive deep inelastic scattering experiments at the DESY ep collider HERA.

A strong signal for double parton scattering (DP) is observed in a $16\mathrm{pb}{}^{\ensuremath{-}1}$ sample of $\overline{p}p\ensuremath{\rightarrow}\ensuremath{\gamma}+3\mathrm{jets}+X$ data from the CDF experiment at the Fermilab Tevatron. The process-independent DP parameter, ${\ensuremath{\sigma}}_{\mathrm{eff}}$, is obtained without reference to theoretical calculations by comparing observed DP events to events with hard scatterings at separate $\overline{p}p$ collisions. The result, ${\ensuremath{\sigma}}_{\mathrm{eff}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(14.5\ifmmode\pm\else\textpm\fi{}{1.7}_{\ensuremath{-}2.3}^{+1.7})\mathrm{mb}$, represents a significant improvement over previous measurements. For the first time, the Feynman $x$ dependence of the ${\ensuremath{\sigma}}_{\mathrm{eff}}$ parameter is investigated, and no dependence is seen.

This paper reports an updated measurement of the Standard Model CP violation parameter $\sin2\beta$ using the CDF Detector at Fermilab. The entire Run I data sample of 110 pb$^{-1}$ of proton antiproton collisions at $\sqrt{s}=1.8 TeV$ is used to identify a signal sample of $\sim 400$ $B \to J/\psi K^0_S$ events, where $J/\psi \to \mu^+\mu^-$ and $K_S^0 \to \pi^+\pi^-$. The flavor of the neutral B meson is identified at the time of production by combining information from three tagging algorithms: a same-side tag, a jet-charge tag, and a soft-lepton tag. A maximum likelihood fitting method is used to determine $\sin2\beta = 0.79 {+0.41\atop-0.44}$(stat+syst). This value of $\sin 2 \beta$ is consistent with the Standard Model prediction, based upon existing measurements, of a large positive CP violating asymmetry in this decay mode.

We report a measurement of the diffraction dissociation differential cross section ${\mathit{d}}^{2}$${\mathrm{\ensuremath{\sigma}}}_{\mathrm{SD}}$/${\mathit{dM}}^{2}$dt for p\ifmmode\bar\else\textasciimacron\fi{}p\ensuremath{\rightarrow}p\ifmmode\bar\else\textasciimacron\fi{}X at \ensuremath{\surd}s =546 and 1800 GeV, ${\mathit{M}}^{2}$/s0.2 and 0\ensuremath{\le}-t\ensuremath{\le}0.4 ${\mathrm{GeV}}^{2}$. Our results are compared to theoretical predictions and to extrapolations from experimental results at lower energies.

A search for tt\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}e\ensuremath{\mu}+X in pp\ifmmode\bar\else\textasciimacron\fi{} collisions at s\ensuremath{\surd}\ifmmode\bar\else\textasciimacron\fi{} TeV is described. The production and decay of top-quark--antiquark pairs is considered in the context of the standard model. The analysis is based on data with an integrated luminosity of 4.4 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ recorded with the Collider Detector at Fermilab. An upper limit on the tt\ifmmode\bar\else\textasciimacron\fi{} cross section is obtained, and the top quark in the mass range 28--72 GeV/${c}^{2}$ is excluded at the 95% C.L. The same limits apply to a possible fourth-generation, charge -(1/3, b' quark, decaying via the charged current.

This Letter describes a direct search for charged Higgs boson production in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ recorded by the Collider Detector at Fermilab. Two-Higgs-double extensions to the standard model predict the existence of charged Higgs bosons $({H}^{\ifmmode\pm\else\textpm\fi{}})$. In such models, the branching fraction for top quarks $B(t\ensuremath{\rightarrow}{H}^{+}b\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}\ensuremath{\nu}b)$ can be large. This search uses the hadronic decays of the tau lepton in this channel to significantly extend previous limits on ${H}^{\ifmmode\pm\else\textpm\fi{}}$ production.

This paper presents a measurement of the mass of the W boson using data collected with the CDF detector during the 1992–1993 collider run at the Fermilab Tevatron. A fit to the transverse mass spectrum of a sample of 3268 W→μν events recorded in an integrated luminosity of 19.7 pb−1 gives MμW=80.310±0.205 (stat)±0.130 (syst) GeV/c2. A fit to the transverse mass spectrum of a sample of 5718 W→eν events recorded in 18.2 pb−1 gives MeW=80.490±0.145 (stat)±0.175 (syst) GeV/c2. Combining the muon and electron results, accounting for correlated uncertainties, yields MW=80.410±0.180 GeV/c2.Received 7 March 1995DOI:https://doi.org/10.1103/PhysRevD.52.4784©1995 American Physical Society

We measure the masses of $b$ hadrons in exclusively reconstructed final states containing a $J/\psi\to\mu^-\mu^+$ decay using $\rm 220 pb^{-1}$ of data collected by the CDF II experiment. We find: m(B^+) = 5279.10 \pm 0.41_{(stat.)} \pm 0.36_{(sys.)} MeVcc, m(B^0) = 5279.63 \pm 0.53_{(stat.)} \pm 0.33_{(sys.)} MeVcc, m(B^0_s) = 5366.01 \pm 0.73_{(stat.)} \pm 0.33_{(sys.)} MeVcc, m(\Lambda^0_b) = 5619.7 \pm 1.2_{(stat.)} \pm 1.2_{(sys.)} MeVcc. m(B^+) - m(B^0) = -0.53 \pm 0.67_{(stat.)} \pm 0.14_{(sys.)} MeVcc, m(B^0_s) - m(B^0) = 86.38 \pm 0.90_{(stat.)} \pm 0.06_{(sys.)} MeVcc m(\Lambda^0_b) - m(B^0) = 339.2 \pm 1.4_{(stat.)} \pm 0.1_{(sys.)} MeVcc. The measurements of the $B^0_s$, $\Lambda^0_b$ mass, $m(B^0_s)-m(B^0)$ and $m(\Lambda^0_b)-m(B^0)$ mass difference are of better precision than the current world averages.

We report the full reconstruction of ${\mathrm{\ensuremath{\chi}}}_{\mathit{c}}$ mesons through the decay chain ${\mathrm{\ensuremath{\chi}}}_{\mathit{c}}$\ensuremath{\rightarrow}J/\ensuremath{\psi} \ensuremath{\gamma}, J/\ensuremath{\psi}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$, using data obtained at the Collider Detector at Fermilab in 2.6\ifmmode\pm\else\textpm\fi{}0.2 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ of p\ifmmode\bar\else\textasciimacron\fi{}p collisions at \ensuremath{\surd}s =1.8 TeV. This exclusive ${\mathrm{\ensuremath{\chi}}}_{\mathit{c}}$ sample is used to measure the ${\mathrm{\ensuremath{\chi}}}_{\mathit{c}}$-meson production cross section times branching fractions. We obtain \ensuremath{\sigma}\ifmmode\times\else\texttimes\fi{}B=3.2\ifmmode\pm\else\textpm\fi{}0.4(stat${)}_{\mathrm{\ensuremath{-}}1.1}^{+1.2}$(syst) nb for ${\mathrm{\ensuremath{\chi}}}_{\mathit{c}}$ mesons decaying to J/\ensuremath{\psi} with ${\mathit{p}}_{\mathit{T}}$&gt;6.0 GeV/c and pseudorapidity \ensuremath{\Vert}\ensuremath{\eta}\ensuremath{\Vert}0.5. From this and the inclusive J/\ensuremath{\psi} cross section we calculate the inclusive b-quark cross section to be 12.0\ifmmode\pm\else\textpm\fi{}4.5 \ensuremath{\mu}b for ${\mathit{p}}_{\mathit{T}}^{\mathit{b}}$&gt;8.5 GeV/c and \ensuremath{\Vert}${\mathit{y}}^{\mathit{b}}$\ensuremath{\Vert}1.

We have determined mW=79.91±0.39 GeV/c2 from an analysis of W→eν and W→μν data from the Collider Detector at Fermilab in ¯pp collisions at √s=1.8 TeV. From this result and the world-average Z mass, the weak mixing angle is determined to be sin2θW=0.232±0.008. An upper bound on the top-quark mass derived from this result is discussed.Received 13 August 1990DOI:https://doi.org/10.1103/PhysRevD.43.2070©1991 American Physical Society

An analysis of ${Z}^{0}$\ensuremath{\rightarrow}${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ and ${Z}^{0}$\ensuremath{\rightarrow}${\ensuremath{\mu}}^{+}$${\ensuremath{\mu}}^{\mathrm{\ensuremath{-}}}$ data from the Collider Detector at Fermilab in p\ifmmode\bar\else\textasciimacron\fi{}p collisions at \ensuremath{\surd}s =1.8 TeV yields a mass of the ${Z}^{0}$ boson of ${M}_{Z}$=90.9\ifmmode\pm\else\textpm\fi{}0.3 (stat+syst)\ifmmode\pm\else\textpm\fi{}0.2 (scale) GeV/${c}^{2}$ and a width of ${\ensuremath{\Gamma}}_{z}$=3.8\ifmmode\pm\else\textpm\fi{}0.8\ifmmode\pm\else\textpm\fi{}1.0 GeV.

We report the first evidence for a fully reconstructed decay mode of the B±c meson in the channel B±c→J/ψπ±, with J/ψ→μ+μ−. The analysis is based on an integrated luminosity of 360 pb−1 in p¯p collisions at 1.96 TeV center of mass energy collected by the Collider Detector at Fermilab. We observe 14.6±4.6 signal events with a background of 7.1±0.9 events, and a fit to the J/ψπ± mass spectrum yields a B±c mass of 6285.7±5.3(stat)±1.2(syst) MeV/c2. The probability of a peak of this magnitude occurring by random fluctuation in the search region is estimated as 0.012%.Received 23 May 2005DOI:https://doi.org/10.1103/PhysRevLett.96.082002©2006 American Physical Society

For comparison of inclusive jet cross sections measured at hadron-hadron colliders to next-to-leading order (NLO) parton-level calculations, the energy deposited in the jet cone by spectator parton interactions must first be subtracted. The assumption made at the Tevatron is that the spectator parton interaction energy is similar to the ambient level measured in minimum bias events. In this paper, we test this assumption by measuring the ambient charged track momentum in events containing large transverse energy jets at $\sqrt{s}=1800$ GeV and $\sqrt{s}=630$ GeV and comparing this ambient momentum with that observed both in minimum bias events and with that predicted by two Monte Carlo models. Two cones in $\eta$--$\phi$ space are defined, at the same pseudo-rapidity, $\eta$, as the jet with the highest transverse energy ($E_T^{(1)}$), and at $\pm 90^o$ in the azimuthal direction, $\phi$. The total charged track momentum inside each of the two cones is measured. The minimum momentum in the two cones is almost independent of $E_T^{(1)}$ and is similar to the momentum observed in minimum bias events, whereas the maximum momentum increases roughly linearly with the jet $E_T^{(1)}$ over most of the measured range. This study will help improve the precision of comparisons of jet cross section data and NLO perturbative QCD predictions. %this is new The distribution of the sum of the track momenta in the two cones is also examined for five different $E_T^{(1)}$ bins. The HERWIG and PYTHIA Monte Carlos are reasonably successful in describing the data, but neither can describe completely all of the event properties.

We present the first observation of exclusive e+e− production in hadron-hadron collisions, using p¯p collision data at √s=1.96 TeV taken by the run II Collider Detector at Fermilab, and corresponding to an integrated luminosity of 532 pb−1. We require the absence of any particle signatures in the detector except for an electron and a positron candidate, each with transverse energy ET>5 GeV and pseudorapidity |η|<2. With these criteria, 16 events are observed compared to a background expectation of 1.9±0.3 events. These events are consistent in cross section and properties with the QED process p¯p→p+e+e−+¯p through two-photon exchange. The measured cross section is 1.6+0.5−0.3(stat)±0.3(syst) pb. This agrees with the theoretical prediction of 1.71±0.01 pb.Received 27 November 2006DOI:https://doi.org/10.1103/PhysRevLett.98.112001©2007 American Physical Society

We present a measurement of the tt¯ production cross section using events with one charged lepton and jets from pp¯ collisions at a center-of-mass energy of 1.96 TeV. A b-tagging algorithm based on the probability of displaced tracks coming from the event interaction vertex is applied to identify b quarks from top decay. Using 318 pb−1 of data collected with the CDF II detector, we measure the tt¯ production cross section in events with at least one restrictive (tight) b-tagged jet and obtain 8.9−1.0+1.0(stat)−1.0+1.1(syst) pb. The cross section value assumes a top quark mass of mt=178 GeV/c2 in the acceptance corrections. The dependence of the cross section on mt is presented in the paper. This result is consistent with other CDF measurements of the tt¯ cross section using different samples and analysis techniques, and has similar systematic uncertainties. We have also performed consistency checks by using the b-tagging probability function to vary the signal-to-background ratio and also using events that have at least two b-tagged jets.20 MoreReceived 21 July 2006DOI:https://doi.org/10.1103/PhysRevD.74.072006©2006 American Physical Society

We present a measurement of the Bc+ meson lifetime in the decay mode Bc+ --> J/Psie+nue using the Collider Detector at Fermilab II detector at the Fermilab Tevatron Collider. From a sample of about of 360 pb(-1) of pp collisions at square root of s = 1.96 TeV, we reconstruct J/Psie+ pairs with invariant mass in the kinematically allowed range 4< M(J/Psie) < 6 GeV/c2. A fit to the decay-length distribution of 238 signal events yields a measured Bc+ meson lifetime of 0.463(-0.065)(+0.073)(stat) +/- 0.036(syst) ps.

We present a measurement of the top quark mass using a sample of tt¯ decays into an electron or a muon, a neutrino, and four jets. The data were collected in pp¯ collisions at s=1.8TeV with the Collider Detector at Fermilab and correspond to an integrated luminosity of 109pb−1. We measure the top quark mass to be 175.9±4.8(stat)±4.9(syst)GeV/c2.Received 30 September 1997DOI:https://doi.org/10.1103/PhysRevLett.80.2767©1998 American Physical Society

We report the first observation of diffractively produced W bosons. In a sample of W -> e nu events produced in p-barp collisions at sqrt{s}=1.8 TeV, we find an excess of events with a forward rapidity gap, which is attributed to diffraction. The probability that this excess is consistent with non-diffractive production is 1.1 10^{-4} (3.8 sigma). The relatively low fraction of W+Jet events observed within this excess implies that mainly quarks from the pomeron, which mediates diffraction, participate in W production. The diffractive to non-diffractive W production ratio is found to be R_W=(1.15 +/- 0.55)%.

We present an analysis of dilepton events originating from top-antitop production in proton-antiproton collisions at sqrt{s}=1.8 TeV at the Fermilab Tevatron Collider. The sample corresponds to an integrated luminosity of 109+-7 pb^{-1}. We observe 9 candidate events, with an estimated background of 2.4+-0.5 events. We determine the mass of the top quark to be M_top = 161+-17(stat.)+-10(syst.) GeV/c^2. In addition we measure a top-antitop production cross section of 8.2+4.4-3.4 pb (where M_top = 175 GeV/c^2 has been assumed for the acceptance estimate).

We report on measurements of the $\ensuremath{\Upsilon}(1S)$, $\ensuremath{\Upsilon}(2S)$, and $\ensuremath{\Upsilon}(3S)$ differential, ${(\frac{{d}^{2}\ensuremath{\sigma}}{d{P}_{t}\mathrm{dy}})}_{y=0}$, and integrated cross sections in $p\overline{p}$ collisions at $\sqrt{s}=1.8$ TeV using a sample of 16.6 \ifmmode\pm\else\textpm\fi{} 0.6 ${\mathrm{pb}}^{\ensuremath{-}1}$ collected by the Collider Detector at Fermilab. The three resonances were reconstructed through the decay $\ensuremath{\Upsilon}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$. Comparison is made to a leading order QCD prediction.

We have used $106{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ by the Collider Detector at Fermilab to measure jet angular distributions in events with two jets in the final state. The angular distributions agree with next to leading order predictions of QCD in all dijet invariant mass regions. The data exclude at 95% CL a model of quark substructure in which only up and down quarks are composite and the contact interaction scale is ${\ensuremath{\Lambda}}_{\mathrm{ud}}^{+}\ensuremath{\le}1.6\mathrm{TeV}$ or ${\ensuremath{\Lambda}}_{\mathrm{ud}}^{\ensuremath{-}}\ensuremath{\le}1.4\mathrm{TeV}$. For a model in which all quarks are composite the excluded regions are ${\ensuremath{\Lambda}}^{+}\ensuremath{\le}1.8\mathrm{TeV}$ and ${\ensuremath{\Lambda}}^{\ensuremath{-}}\ensuremath{\le}1.6\mathrm{TeV}$.

We present results from the measurement of the inclusive jet cross section for jet transverse energies from 40 to 465 GeV in the pseudorapidity range $0.1&lt;|\ensuremath{\eta}|&lt;0.7.$ The results are based on 87 ${\mathrm{pb}}^{\ensuremath{-}1}$ of data collected by the CDF Collaboration at the Fermilab Tevatron collider. The data are consistent with previously published results. The data are also consistent with QCD predictions given the flexibility allowed from current knowledge of the proton parton distributions. We develop a new procedure for ranking the agreement of the parton distributions with data and find that the data are best described by QCD predictions using the parton distribution functions which have a large gluon contribution at high ${E}_{T}$ (CTEQ4HJ).

We describe a measurement of the charge asymmetry of leptons from W boson decays in the rapidity range 0 < |y l | < 2.5 using W → eν, µν events from 110 ± 7 pb -1 of data collected by the CDF detector during 1992-95.The asymmetry data constrain the ratio of d and u quark momentum distributions in the proton over the x range of 0.006 to 0.34 at Q 2 ≈ M 2 W .The asymmetry predictions that use parton distribution functions obtained from previously published CDF data in the central

We report on a study of jet shapes in inclusive jet production in p¯p collisions at √s=1.96 TeV using the upgraded collider detector at Fermilab in Run II (CDF II) and based on an integrated luminosity of 170 pb−1. Measurements are carried out on jets with rapidity 0.1<|Yjet|<0.7 and transverse momentum 37 GeV/c<PjetT<380 GeV/c. The jets have been corrected to the hadron level. The measured jet shapes are compared to leading-order QCD parton-shower Monte Carlo predictions as implemented in the PYTHIA and HERWIG programs. PYTHIA, tuned to describe the underlying event as measured in CDF Run I, provides a better description of the measured jet shapes than does PYTHIA or HERWIG with their default parameters.2 MoreReceived 9 May 2005DOI:https://doi.org/10.1103/PhysRevD.71.112002©2005 American Physical Society

We present a measurement of the mass of the W boson using data collected with the CDF detector during the 1992-93 collider run at the Fermilab Tevatron.A t to the transverse mass spectrum of a sample of 3268 W ! events recorded in an integrated luminosity of 19.7 pb 1 gives a mass M W = 80:310 0:205 (stat.)0:130 (syst.)GeV/c 2 .A t to the transverse mass spectrum of a sample of 5718 W ! e events recorded in 18.2 pb 1 gives a mass M e W = 80:490 0:145 (stat.)0:175 (syst.)GeV/c 2 .Combining the electron and muon results, accounting for correlated uncertainties, yields a mass M W = 80:410 0:180 GeV/c 2 .

We report a measurement of the forward-backward charge asymmetry of electrons from W boson decays in p anti-p collisions at s**(1/2) = 1.96 TeV using a data sample of 170 pb-1 collected by the Collider Detector at Fermilab. The asymmetry is measured as a function of electron rapidity and transverse energy and provides new input on the momentum fraction dependence of the u and d quark parton distribution within the proton.

Inclusive jet production at $\sqrt{s}=1.8$ TeV has been measured in the CDF detector at the Fermilab Tevatron $\overline{p}p$ Collider. Jets with transverse energies (${E}_{t}$) up to 250 GeV have been observed. The ${E}_{t}$ dependence of the inclusive jet cross section is consistent with leading-order quantum-chromodynamic calculations, and comparison with lower-energy data shows deviations from scaling consistent with QCD. A lower limit of 700 GeV (95% confidence level) is placed on the quark compositeness scale parameter ${\ensuremath{\Lambda}}_{c}$ associated with an effective contact interaction.

We present measurements of the ${B}^{+}$ meson total cross section and differential cross section $d\ensuremath{\sigma}{/dp}_{T}.$ The measurements use a $98\ifmmode\pm\else\textpm\fi{}4$ ${\mathrm{pb}}^{\ensuremath{-}1}$ sample of $p\overline{p}$ collisions at $\sqrt{s}=1.8 \mathrm{TeV}$ collected by the CDF detector. Charged B meson candidates are reconstructed through the decay ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{\ifmmode\pm\else\textpm\fi{}}$ with $J/\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\psi}}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}.$ The total cross section, measured in the central rapidity region $|y|&lt;1.0$ for ${p}_{T}(B)&gt;6.0 \mathrm{GeV}/c,$ is $3.6\ifmmode\pm\else\textpm\fi{}0.6(\mathrm{stat}\ensuremath{\bigoplus} \mathrm{syst}) \ensuremath{\mu}\mathrm{b}.$ The measured differential cross section is substantially larger than typical QCD predictions calculated to next-to-leading order.

We report the observation and measurement of the rate of diffractive dijet production at the Fermilab Tevatron $\overline{p}p$ collider at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$. In events with two jets of ${E}_{T}&gt;20\mathrm{GeV}$, $1.8&lt;|\ensuremath{\eta}|&lt;3.5$, and ${\ensuremath{\eta}}_{1}{\ensuremath{\eta}}_{2}&gt;0$, we find that the diffractive to nondiffractive production ratio is ${R}_{\mathrm{JJ}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}[0.75\ifmmode\pm\else\textpm\fi{}0.05(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.09(\mathrm{syst})]%$. By comparing this result, in combination with our measured rate for diffractive $W$ boson production reported previously, with predictions based on a hard partonic pomeron structure, we determine the pomeron gluon fraction to be ${f}_{g}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.7\ifmmode\pm\else\textpm\fi{}0.2$.

The dilepton mass spectrum in $p\overline{p}\ensuremath{\rightarrow}{l}^{+}{l}^{\ensuremath{-}}+X$ interactions is studied using dielectrons (ee) and dimuons (\ensuremath{\mu}\ensuremath{\mu}) in $110{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected with the Collider Detector at Fermilab. The data are consistent with standard model predictions. The mass spectrum, being a probe for new physics, is examined for new interactions of quarks and leptons from a common composite structure. Assuming a contact interaction with the conventional coupling ${g}_{0}^{2}/4\ensuremath{\pi}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$, limits on chiral quark-electron and quark-muon compositeness scales in the range of 2.5 to 4.2 TeV are obtained.

We present results of searches for the top quark in $p\overline{p}$ collisions at $\sqrt{s}=1.8$ TeV. The data sample was collected during 1988-1989 at the Fermilab Tevatron Collider and has an integrated luminosity of 4.1 ${\mathrm{pb}}^{\ensuremath{-}1}$. We have extended our previous search for $e\ensuremath{\mu}$ final states to include the $\mathrm{ee}$ and $\ensuremath{\mu}\ensuremath{\mu}$ channels. In addition, we have searched for a low-transverse-momentum muon as a tag of the bottom quark in top decay events with a lepton and at least two jets. We obtain a lower limit on the top-quark mass of 91 GeV/${\mathit{c}}^{2}$ at the 95% confidence level assuming standard-model charged-current decays.

We search for Z' bosons in dielectron events produced in ppbar collisions at sqrt{s}=1.96 TeV, using a 0.45 fb^(-1) dataset accumulated with the CDF II detector at the Fermilab Tevatron. To identify the Z' --> e^+e^- signal, both the dielectron invariant mass distribution and the angular distribution of the electron pair are used. No evidence of a signal is found, and 95% confidence level lower limits are set on the Z' mass for several models. Limits are also placed on the mass and gauge coupling of a generic Z', as well as on the contact interaction mass scales for different helicity structure scenarios.

We present a measurement of the b-quark cross section in 1.8 TeV p-p\ifmmode\bar\else\textasciimacron\fi{} collisions recorded with the Collider Detector at Fermilab using muonic b-quark decays. In the central rapidity region (\ensuremath{\Vert}${\mathit{y}}^{\mathit{b}}$\ensuremath{\Vert}1.0), the cross section is 295\ifmmode\pm\else\textpm\fi{}21\ifmmode\pm\else\textpm\fi{}75 nb (59\ifmmode\pm\else\textpm\fi{}14\ifmmode\pm\else\textpm\fi{}15 nb) for ${\mathit{p}}_{\mathit{T}}^{\mathit{b}}$&gt;21 GeV/c (29 GeV/c). Comparisons are made to previous measurements and next-to-leading order QCD calculations.

An analysis of high-transverse-momentum electrons using data from the Collider Detector at Fermilab (CDF) of ¯pp collisions at √s=1800 GeV yields values of the production cross section times branching ratio for W and Z0 bosons of σ(¯pp→WX→eνX)=2.19±0.04(stat)±0.21(syst) nb and σ(¯pp→Z0X→e+e−X)=0.209±0.013(stat)±0.017(syst) nb. Detailed descriptions of the CDF electron identification, background, efficiency, and acceptance are included. Theoretical predictions of the cross sections that include a mass for the top quark larger than the W mass, current values of the W and Z0 masses, and higher-order QCD corrections are in good agreement with these measured values.Received 13 November 1990DOI:https://doi.org/10.1103/PhysRevD.44.29©1991 American Physical Society

The first prompt photon measurement from the CDF experiment at the Fermilab $p\overline{p}$ Collider is presented. Two independent methods are used to measure the cross section: one for high transverse momentum (${P}_{T}$) and one for lower ${P}_{T}$. Comparisons to various theoretical calculations are shown. The cross section agrees qualitatively with QCD calculations but has a steeper slope at low ${P}_{T}$.

We present a search for neutral supersymmetric Higgs bosons decaying to $\ensuremath{\tau}$ pairs produced in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. The data, corresponding to $310\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ integrated luminosity, were collected with the Collider Detector at Fermilab in run II of the Tevatron. No significant excess above the standard model backgrounds is observed. We set exclusion limits on the production cross section times branching fraction to $\ensuremath{\tau}$ pairs for Higgs boson masses in the range from 90 to $250\text{ }\text{ }\mathrm{GeV}/{c}^{2}$.

We present a new measurement of the top quark mass in $t\overline{t}$ events in which both $W$ bosons from top quarks decay into leptons $(e\ensuremath{\nu},\ensuremath{\mu}\ensuremath{\nu})$. We use events collected by the CDF experiment from $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ at the Tevatron collider. We measure a top quark mass of $167.4\ifmmode\pm\else\textpm\fi{}10.3(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}4.8(\mathrm{syst})\phantom{\rule{0ex}{0ex}}\mathrm{GeV}{/c}^{2}$ from a sample of eight events. We combine this result with previous CDF measurements in other decay channels to obtain a final mass value of $176.0\ifmmode\pm\else\textpm\fi{}6.5\mathrm{GeV}{/c}^{2}$.

We present a measurement of the W boson mass using data collected with the CDF detector during the 1994-95 collider run at the Fermilab Tevatron. A fit to the transverse mass spectrum of a sample of 30,115 W -&gt; enu events recorded in an integrated luminosity of 84 pb^(-1) gives a mass Mw = 80.473 +- 0.065(stat.) +- 0.092(syst.) GeV/c^2. A fit to the transverse mass spectrum of a sample of 14,740 W -&gt; munu events from 80 pb^(-1) gives a mass Mw = 80.465 +- 0.100(stat.) +- 0.103(syst.) GeV/c^2. The dominant contributions to the systematic uncertainties are the uncertainties in the electron energy scale and the muon momentum scale, 0.075 GeV/c^2 and 0.085 GeV/c^2, respectively. The combined value for the electron and muon channel is Mw = 80.470 +- 0.089 GeV/c^2. When combined with previously published CDF measurements, we obtain Mw = 80.433 +- 0.079 GeV/c^2.

In $p\overline{p}$ collisions at $\sqrt{s}=1.8$ TeV we find jet events with a rapidity gap topology. The number of hadrons in the rapidity interval $\ensuremath{\Delta}{\ensuremath{\eta}}_{D}$ between leading-jet cones was sampled by charged tracks with ${P}_{T}&gt;400$ MeV/c. We find excess trackless events beyond that expected in a smooth multiplicity distribution. In a control region outside $\ensuremath{\Delta}{\ensuremath{\eta}}_{D}$ we see no excess. For $\ensuremath{\Delta}{\ensuremath{\eta}}_{D}&gt;0.8$, the fraction of excess trackless events, consistent with estimates based on exchange of color-singlet digluons, is $R(\mathrm{gap})=\frac{{\ensuremath{\sigma}}_{\mathrm{jet}}(\mathrm{gap})}{{\ensuremath{\sigma}}_{\mathrm{jet}}}=0.0085\ifmmode\pm\else\textpm\fi{}{0.0012(\mathrm{stat})}_{\ensuremath{-}0.0012}^{+0.0024}(\mathrm{syst})$.

We present measurements of correlated b¯b cross sections, μ−μ correlations, the average B0¯B0 mixing parameter ¯χ, and a limit on the CP-violating parameter εB. For these measurements, we use muon pairs from b¯b double semileptonic decays. The data used in this analysis were taken with the Collider Detector at Fermilab and represent an integrated luminosity of 17.4±0.6 pb−1. The results concerning b¯b production correlations are compared to predictions of next-to-leading order QCD computations.Received 12 August 1996DOI:https://doi.org/10.1103/PhysRevD.55.2546©1997 American Physical Society

We have measured the cross sections $d^2\sigma/dP_T d\eta$ for production of isolated direct photons in \pbarp collisions at two different center-of-mass energies, 1.8 TeV and 0.63 TeV, using the Collider Detector at Fermilab (CDF). The normalization of both data sets agree with the predictions of Quantum Chromodynamics (QCD) for photon transverse momentum ($P_T$) of 25 GeV/c, but the shapes versus photon $P_T$ do not. These shape differences lead to a significant disagreement in the ratio of cross sections in the scaling variable $x_T (\equiv 2P_T/\sqrt{s}$). This disagreement in the $x_T$ ratio is difficult to explain with conventional theoretical uncertainties such as scale dependence and parton distribution parameterizations.

We report a measurement of the ttbar production cross section using dilepton events with jets and missing transverse energy in ppbar collisions at a center-of-mass energy of 1.96 TeV. Using a 197 +/- 12 pb-1 data sample recorded by the upgraded Collider Detector at Fermilab, we use two complementary techniques to select candidate events. We compare the number of observed events and selected kinematical distributions with the predictions of the Standard Model and find good agreement. The combined result of the two techniques yields a ttbar production cross section of 7.0 +2.4/-2.1(stat.) +1.6/-1.1(syst.) +/- 0.4(lum.) pb.

We report a new measurement of dijet production by color-singlet exchange in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ at the Fermilab Tevatron. In a sample of events with two jets of transverse energy ${E}_{T}^{\mathrm{jet}}&gt;20\mathrm{GeV}$, pseudorapidity in the range $1.8&lt;|{\ensuremath{\eta}}^{\mathrm{jet}}|&lt;3.5$, and ${\ensuremath{\eta}}_{1}{\ensuremath{\eta}}_{2}&lt;0$, we find that a fraction $R\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}[1.13\ifmmode\pm\else\textpm\fi{}0.12(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.11(\mathrm{syst})]%$ has a pseudorapidity gap within $|\ensuremath{\eta}|&lt;1$ between the jets that can be attributed to color-singlet exchnage. The fraction $R$ shows no significant dependence on ${E}_{T}^{\mathrm{jet}}$ or on the pseudorapidity separation between the jets.

This report describes a measurement of the top quark mass in $p\overline{p}$ collisions at a center of mass energy of 1.8 TeV. The data sample was collected with the CDF detector during the 1992--1995 collider run at the Fermilab Tevatron, and corresponds to an integrated luminosity of 106 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$. Candidate $t\overline{t}$ events in the ``$\mathrm{l}\mathrm{e}\mathrm{p}\mathrm{t}\mathrm{o}\mathrm{n}+\mathrm{j}\mathrm{e}\mathrm{t}\mathrm{s}$'' decay channel provide our most precise measurement of the top quark mass. For each event a top quark mass is determined by using energy and momentum constraints on the production of the $t\overline{t}$ pair and its subsequent decay. A likelihood fit to the distribution of reconstructed masses in the data sample gives a top quark mass in the $\mathrm{l}\mathrm{e}\mathrm{p}\mathrm{t}\mathrm{o}\mathrm{n}+\mathrm{j}\mathrm{e}\mathrm{t}\mathrm{s}$ channel of $176.1\ifmmode\pm\else\textpm\fi{}5.1(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}5.3(\mathrm{syst})\mathrm{}\mathrm{GeV}{/c}^{2}.$ Combining this result with measurements from the ``all-hadronic'' and ``dilepton'' decay topologies yields a top quark mass of $176.1\ifmmode\pm\else\textpm\fi{}6.6\mathrm{GeV}{/c}^{2}.$

We present the first observation of the all hadronic decay of $t\overline{t}$ pairs. The analysis is performed using $109{\mathrm{pb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ collected with the Collider Detector at Fermilab. We observe an excess of events with five or more jets, including one or two $b$ jets, relative to background expectations. Based on this excess we evaluate the production cross section to be in agreement with previous results. We measure the top mass to be $186\ifmmode\pm\else\textpm\fi{}10\ifmmode\pm\else\textpm\fi{}12\mathrm{GeV}{/c}^{2}$.

We present a search for the flavor-changing neutral current decays B0d→μ+μ− and B0s→μ+μ− in p¯p collisions at √s=1.8 TeV, using 98pb−1 of data collected at the Collider Detector at Fermilab. We find one candidate event for these decays, which is consistent with the background estimates, and set upper limits on the branching fractions of B(B0d→μ+μ−)<8.6×10−7 and B(B0s→μ+μ−)<2.6×10−6 at 95% confidence level.Received 21 November 1997DOI:https://doi.org/10.1103/PhysRevD.57.R3811©1998 American Physical Society

We present a measurement of $\sigma \cdot B(W \to e \nu)$ and $\sigma \cdot B(Z^0 \to e^+e^-)$ in proton - antiproton collisions at $\sqrt{s} =1.8$ TeV using a significantly improved understanding of the integrated luminosity. The data represent an integrated luminosity of 19.7 pb$^{-1}$ from the 1992-1993 run with the Collider Detector at Fermilab (CDF). We find $\sigma \cdot B(W \to e \nu) = 2.49 \pm 0.12$~nb and $\sigma \cdot B(Z^0 \to e^+e^-) = 0.231 \pm 0.012$~nb.

We report on a search for B(0)(s)-->micro(+)micro(-) and B(0)(d)-->micro(+)micro(-) decays in pp collisions at square root of s=1.96 TeV using 171 pb(-1) of data collected by the CDF II experiment at the Fermilab Tevatron Collider. The decay rates of these rare processes are sensitive to contributions from physics beyond the standard model. One event survives all our selection requirements, consistent with the background expectation. We derive branching ratio limits of B(B(0)(s)-->micro(+)micro(-))<5.8x10(-7) and B(B(0)(d)-->micro(+)micro(-))<1.5x10(-7) at 90% confidence level.

We report on a study of $W+$ photon production in approximately 20 ${\mathrm{pb}}^{\ensuremath{-}1}$ of $p\ensuremath{-}\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8$ TeV recorded with the Collider Detector at Fermilab. Our results are in good agreement with standard model expectations and are used to obtain limits on anomalous $\mathrm{CP}$-conserving $\mathrm{WW}\ensuremath{\gamma}$ couplings of $\ensuremath{-}2.3&lt;\ensuremath{\Delta}\ensuremath{\kappa}&lt;2.2$ for $\ensuremath{\lambda}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ and $\ensuremath{-}0.7&lt;\ensuremath{\lambda}&lt;0.7$ for $\ensuremath{\Delta}\ensuremath{\kappa}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ at 95% C.L. We obtain the same limits for $\mathrm{CP}$-violating couplings. These results provide limits on the higher-order electromagnetic moments of the $W$ boson of $0.8&lt;{g}_{W}&lt;3.1$ for ${q}_{W}^{e}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$ and $\ensuremath{-}0.6&lt;{q}_{W}^{e}&lt;2.7$ for ${g}_{W}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2$ at 95% C.L.

The charge asymmetry has been measured using $19,039~W$ decays recorded by the CDF detector during the 1992-93 run of the Tevatron Collider. The asymmetry is sensitive to the ratio of $d$ and $u$ quark distributions to $x<0.01$ at $Q^2 \approx M_W^2$, where nonperturbative effects are minimal. It is found that of the two current sets of parton distributions, those of Martin, Roberts and Stirling (MRS) are favored over the sets most recently produced by the CTEQ collaboration. The $W$ asymmetry data provide a stronger constraints on $d/u$ ratio than the recent measurements of $F_2^{\mu n}/F_2^{\mu p}$ which are limited by uncertainties originating from deutron corrections.

We update the measurement of the $t\overline{t}$ production cross section using the CDF detector at the Fermilab Tevatron. This measurement uses $t\overline{t}$ decays to the final states $e+\ensuremath{\nu}+\mathrm{jets}$ and $\ensuremath{\mu}+\ensuremath{\nu}+\mathrm{jets}.$ We search for b quarks from t decays via secondary-vertex identification or the identification of semileptonic decays of the b and cascade c quarks. The background to the $t\overline{t}$ production is determined primarily through a Monte Carlo simulation. However, we calibrate the simulation and evaluate its uncertainty using several independent data samples. For a top quark mass of $175\mathrm{GeV}{/c}^{2},$ we measure ${\ensuremath{\sigma}}_{t\overline{t}}=5.1\ifmmode\pm\else\textpm\fi{}1.5\mathrm{pb}$ and ${\ensuremath{\sigma}}_{t\overline{t}}=9.2\ifmmode\pm\else\textpm\fi{}4.3\mathrm{pb}$ using the secondary vertex and the lepton tagging algorithms, respectively. Finally, we combine these results with those from other $t\overline{t}$ decay channels and obtain ${\ensuremath{\sigma}}_{t\overline{t}}{=6.5}_{\ensuremath{-}1.4}^{+1.7}\mathrm{pb}.$

We have used $19{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected with the Collider Detector at Fermilab to search for new particles decaying to dijets. We exclude at 95% confidence level models containing the following new particles: axigluons with mass between 200 and 870 GeV/ ${c}^{2}$, excited quarks with mass between 80 and 570 GeV/ ${c}^{2}$, and color octet technirhos with mass between 320 and 480 GeV/ ${c}^{2}$.

The results based on 1992-95 data (Run 1) from the CDF and DO experiments on the measurements of the W boson mass and width are presented, along with the combined results. We report a Tevatron collider average M_W = 80.456 +- 0.059 GeV. We also report the Tevatron collider average of the directly measured W boson width Gamma_W = 2.115 +- 0.105 GeV. We describe a new joint analysis of the direct W mass and width measurements. Assuming the validity of the standard model, we combine the directly measured W boson width with the width extracted from the ratio of W and Z boson leptonic partial cross sections. This combined result for the Tevatron is Gamma_W = 2.135 +- 0.050 GeV. Finally, we use the measurements of the direct total W width and the leptonic branching ratio to extract the leptonic partial width Gamma(W -> e nu) = 224 +- 13 MeV.