P. Azzi

In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in the same 100 km tunnel. The scientific capabilities of the integrated FCC programme would serve the worldwide community throughout the 21st century. The FCC study also investigates an LHC energy upgrade, using FCC-hh technology. This document constitutes the second volume of the FCC Conceptual Design Report, devoted to the electron-positron collider FCC-ee. After summarizing the physics discovery opportunities, it presents the accelerator design, performance reach, a staged operation scenario, the underlying technologies, civil engineering, technical infrastructure, and an implementation plan. FCC-ee can be built with today’s technology. Most of the FCC-ee infrastructure could be reused for FCC-hh. Combining concepts from past and present lepton colliders and adding a few novel elements, the FCC-ee design promises outstandingly high luminosity. This will make the FCC-ee a unique precision instrument to study the heaviest known particles (Z, W and H bosons and the top quark), offering great direct and indirect sensitivity to new physics.

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 review the physics opportunities of the Future Circular Collider, covering its e+e-, pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the synergy and complementarity of the different colliders, which will contribute to a uniquely coherent and ambitious research programme, providing an unmatchable combination of precision and sensitivity to new physics.

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries.

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).

A bstract The discovery by the ATLAS and CMS experiments of a new boson with mass around 125 GeV and with measured properties compatible with those of a Standard-Model Higgs boson, coupled with the absence of discoveries of phenomena beyond the Standard Model at the TeV scale, has triggered interest in ideas for future Higgs factories. A new circular e + e − collider hosted in a 80 to 100 km tunnel, TLEP, is among the most attractive solutions proposed so far. It has a clean experimental environment, produces high luminosity for top-quark, Higgs boson, W and Z studies, accommodates multiple detectors, and can reach energies up to the $$ \mathrm{t}\overline{\mathrm{t}} $$ threshold and beyond. It will enable measurements of the Higgs boson properties and of Electroweak Symmetry-Breaking (EWSB) parameters with unequalled precision, offering exploration of physics beyond the Standard Model in the multi-TeV range. Moreover, being the natural precursor of the VHE-LHC, a 100 TeV hadron machine in the same tunnel, it builds up a long-term vision for particle physics. Altogether, the combination of TLEP and the VHE-LHC offers, for a great cost effectiveness, the best precision and the best search reach of all options presently on the market. This paper presents a first appraisal of the salient features of the TLEP physics potential, to serve as a baseline for a more extensive design study.

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre-of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries.

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).

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.

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 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.

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

A silicon microstrip vertex detector has been constructed and installed in the Collider Detector at Fermilab. The device has been designed to operate at a hadron collider. It began collecting data in May of 1992 and has functioned within specification. Technical details are presented on all aspects of the system and its performance.

The CMS collaboration has developed a fast Monte Carlo simulation of the CMS detector with event production rates ∼100 times faster than the GEANT4-based simulation, with nonetheless comparable accuracy for most of the physics objects typically considered in the analyses. We discuss basic technical principles of the CMS Fast Simulation and their implementation in the different components of the detector: the silicon tracker, the electromagnetic calorimeter, the hadronic calorimeter, the muon system, the Level 1 and the High Level Trigger. A few comparisons of the Fast Simulation results both with the GEANT4-based Full Simulation and with the LHC data are shown.

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.

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.

The Intermediate Silicon Layers (ISL) detector is currently being built as part of the CDF II detector upgrade project. The ISL detector will significantly improve tracking in the central region and, together with the Silicon Vertex detector, provide stand-alone 3D track information in the forward/backward regions. In this article, we present the quality of the production sensors manufactured by Hamamatsu Photonics, which account for roughly half of the silicon sensors used in the ISL detector.

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

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 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.

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 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.

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 present the results of a search for doubly charged Higgs bosons (H+/-+/-) decaying to dileptons (ll(')) using approximately 240 pb(-1) of pp collision data collected by the CDF II experiment at the Fermilab Tevatron. In our search region, given by same-sign ll(') mass m(ll('))>80 GeV/c(2) (100 GeV/c(2) for ee channel), we observe no evidence for H+/-+/- production. We set limits on sigma(pp -->H++H---->l(+)l('+)l(-)l('-)) as a function of the mass of the H+/-+/- and the chirality of its couplings. Assuming exclusive same-sign dilepton decays, we derive lower mass limits on H(+/-+/-)(L) of 133, 136, and 115 GeV/c(2) in the ee, mumu, and emu channels, respectively, and a lower mass limit of 113 GeV/c(2) on H(+/-+/-)(R) in the mumu channel, all at the 95% confidence level.

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.

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 a measurement of the top quark pair production cross section in p¯p collisions at √s=1.96 TeV using 318 pb−1 of data collected with the Collider Detector at Fermilab. We select t¯t decays into the final states eν+jets and μν+jets, in which at least one b quark from the t-quark decays is identified using a secondary vertex-finding algorithm. Assuming a top quark mass of 178 GeV/c2, we measure a cross section of 8.7±0.9(stat)+1.1−0.9(syst) pb. We also report the first observation of t¯t with significance greater than 5σ in the subsample in which both b quarks are identified, corresponding to a cross section of 10.1+1.6−1.4(stat)+2.0−1.3(syst) pb.Received 6 June 2006DOI:https://doi.org/10.1103/PhysRevLett.97.082004©2006 American Physical Society

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 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.

The Collider Detector at Fermilab (CDF) radiation hardened silicon vertex detector (SVX') is described. The new detector has several improvements over its predecessor such as better signal to noise and higher efficiency. It is expected to have a radiation tolerance in excess of 1 Mrad. It has been taking data for several months and some preliminary results are shown.

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 have performed a search for gluinos (g) and scalar quarks (q) in a data sample of 84 pb(-1) of pp collisions at square root[s] = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and three or more jets, a characteristic signature in R-parity-conserving supersymmetric models. The analysis has been performed "blind," in that the inspection of the signal region is made only after the predictions from standard model backgrounds have been calculated. Comparing the data with predictions of constrained supersymmetric models, we exclude gluino masses below 195 GeV/c2 (95% C.L.), independent of the squark mass. For the case m(q) approximately m(g), gluino masses below 300 GeV/c2 are excluded.

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 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 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 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.

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 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 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 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.

We report the first observation of dijet events with a double Pomeron exchange topology produced in &pmacr;p collisions at sqrt[s] = 1800 GeV. The events are characterized by a leading antiproton, two jets in the central pseudorapidity region, and a large rapidity gap on the outgoing proton side. We present results on jet kinematics and production rates, compare them with corresponding results from single diffractive and inclusive dijet production, and test factorization.

We present the results of a search for neutral Higgs bosons produced in association with b quarks in pp-->bb(phi)-->bbb final states with 91+/-7 pb(-1) of pp collisions at sqrt[s] = 1.8 TeV recorded by the Collider Detector at Fermilab. We find no evidence of such a signal and the data are interpreted in the context of the neutral Higgs sector of the minimal supersymmetric extension of the standard model. With basic parameter choices for the supersymmetric scale and the stop-quark mixing, we derive 95% C.L. lower mass limits for neutral Higgs bosons for tan(beta) values in excess of 35.

Direct limits are set on W W Z and W W three-boson couplings in a search for W W and W Z production with high transverse momentum in pp collisions at p s = 1:8 TeV, using the Collider Detector at Fermilab.The results are in agreement with the SU(2) U(1) model of electroweak interactions.Assuming Standard Model W W couplings, the limits are interpreted as direct evidence for a non-zero W W Z coupling at subprocess energies near 500 GeV.Alternatively, assuming identical W W Z and W W couplings, bounds

We present the results of a search for third generation leptoquark (LQ) pairs in $110\ifmmode\pm\else\textpm\fi{}8{\mathrm{pb}}^{\ensuremath{-}1}$of $\overline{p}p$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ recorded by the Collider Detector at Fermilab. We assume third generation leptoquarks decay to a $\ensuremath{\tau}$ lepton and a $b$ quark with branching ratio $\ensuremath{\beta}$. We observe one candidate event, consistent with standard model background expectations. We place upper limits on $\ensuremath{\sigma}(\overline{p}p\ensuremath{\rightarrow}\mathrm{LQ}\overline{\mathrm{LQ}})\ifmmode \dot{}\else \.{}\fi{}{\ensuremath{\beta}}^{2}$ as a function of the leptoquark mass ${M}_{\mathrm{LQ}}$. We exclude at 95% confidence level scalar leptoquarks with ${M}_{\mathrm{LQ}}&lt;99\mathrm{GeV}{/c}^{2}$, gauge vector leptoquarks with ${M}_{\mathrm{LQ}}&lt;225\mathrm{GeV}{/c}^{2}$, and nongauge vector leptoquarks with ${M}_{\mathrm{LQ}}&lt;170\mathrm{GeV}{/c}^{2}$ for $\ensuremath{\beta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$.

We present a measurement of the ratio of top-quark branching fractions R=B(t→Wb)/B(t→Wq), where q can be a b, s, or a d quark, using lepton-plus-jets and dilepton data sets with an integrated luminosity of ∼162 pb−1 collected with the Collider Detector at Fermilab during Run II of the Tevatron. The measurement is derived from the relative numbers of t¯t events with different multiplicity of identified secondary vertices. We set a lower limit of R>0.61 at 95% confidence level.Received 27 May 2005DOI:https://doi.org/10.1103/PhysRevLett.95.102002©2005 American Physical Society

We report a search for the production of long-lived charged massive particles in a data sample of $90\text{ }{\mathrm{p}\mathrm{b}}^{\ensuremath{-}1}$ of $\sqrt{s}=1.8\text{ }\mathrm{T}\mathrm{e}\mathrm{V}$ $p\overline{p}$ collisions recorded by the Collider Detector at Fermilab. The search uses the muonlike penetration and anomalously high ionization energy loss signature expected for such a particle to discriminate it from backgrounds. The data are found to agree with background expectations, and cross section limits of $\mathcal{O}(1)$ pb are derived using two reference models, a stable quark and a stable scalar lepton.

A search for new particles (X) that decay to electron or muon pairs has been performed using approximately 200 pb**(-1) of pbarp collision data at sqrt(s)=1.96 TeV collected by the CDF II experiment at the Fermilab Tevatron. Limits on sigma(ppbar -> X)*BR(X -> ll) are presented as a function of dilepton invariant mass m(ll) > 150 GeV/c**2, for different spin hypotheses (0, 1, or 2). The limits are approximately 25 fb for m(ll) > 600 GeV/c**2. Lower mass bounds for X from representative models beyond the Standard Model including heavy neutral gauge bosons are presented.

We use the transverse momentum spectrum of leptons in the decay chain t-->bW with W-->lnu to measure the helicity of the W bosons in the top quark rest frame. Our measurement uses a t&tmacr; sample isolated in 106+/-4 pb(-1) of data collected in p&pmacr; collisions at sqrt[s] = 1.8 TeV with the CDF detector at the Fermilab Tevatron. Assuming a standard V-A weak decay, we find that the fraction of W's with zero helicity in the top rest frame is F0 = 0.91+/-0. 37(stat)+/-0.13(syst), consistent with the standard model prediction of F0 = 0.70 for a top mass of 175 GeV/c(2).

We report on a search for supersymmetric squark and gluino particles in a data sample of 19 pb−1 of pp¯ collisions at s=1.8 TeV recorded by the Collider Detector at Fermilab. We searched for events containing jets plus appreciable missing transverse energy (E/T). This signature is indicative of pair production and subsequent decay of squarks and/or gluinos. After all cuts, there are 18 events with E/T>60 GeV and three jets, and 6 events with E/T>60 GeV and four jets. These numbers of events are consistent with estimates of standard model processes plus detector-induced background sources. The analysis yields lower limits on gluino and squark masses, based on the predictions from the mnimal supersymmetric extension of the standard model. At the 95% confidence level, we find gluino and squark mass limits up to 216 GeV/c2, assuming equal gluino and squark masses, and gluino mass limits up to 173 GeV/c2, independent of squark mass.Received 11 February 1997DOI:https://doi.org/10.1103/PhysRevD.56.R1357©1997 American Physical Society

We present a search for first generation leptoquark with 110pb^1 of data collected with the CDF detector. We set 95% C.L. cross section limits as a function of the leptoquark mass.

The average bottom-hadron and individual B+, B0, and Bs0 meson lifetimes have been determined using decays with a J/ψ→μ+μ− in the final state. The data sample consists of 110 pb−1 of p¯p collisions at s=1.8 TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992–1995. For the average lifetime of B hadrons decaying into J/ψ+X, we obtain 〈τb〉=1.533±0.015(stat)−0.031+0.035(syst)ps. For the B+ and B0 meson lifetimes, we determine τ(B+)=1.68±0.07(stat)±0.02(syst)ps, τ(B0)=1.58±0.09(stat)±0.02(syst)ps, and τ(B+)/τ(B0)=1.06±0.07(stat)±0.02(syst). For the Bs0 meson lifetime, we find τ(Bs0)=1.34−0.19+0.23(stat)±0.05(syst) ps. Received 27 October 1997DOI:https://doi.org/10.1103/PhysRevD.57.5382©1998 American Physical Society

Inclusive jet cross sections have been measured in p\ifmmode\bar\else\textasciimacron\fi{}p collisions at \ensuremath{\surd}s =546 and 1800 GeV, using the Collider Detector at Fermilab. The ratio of jet cross sections is compared to predictions from simple scaling and O(${\mathit{a}}_{\mathit{s}}^{3}$) QCD. Our data exclude scaling and lie (1.5--2.4)\ensuremath{\sigma} below a range of QCD predictions.

We have searched for anomalous production of missing ${E}_{T}(E{}_{T})$, jets, leptons $(e,\ensuremath{\mu},\ensuremath{\tau})$, $b\mathrm{quarks}$, or additional photons in events containing two isolated, central $(|\ensuremath{\eta}|&lt;1.0)$ photons with ${E}_{T}&gt;12\mathrm{GeV}$. The results are consistent with standard model expectations, with the possible exception of one event that has in addition to the two photons a central electron, a $\mathrm{high}\ensuremath{-}{E}_{T}$ electromagnetic cluster, and large $E{}_{T}$. We set limits using two specific supersymmetry scenarios for production of diphoton events with $E{}_{T}$.

We have searched for new, heavy, charged bosons ${W}^{\ensuremath{'}}$ through the decay ${W}^{\ensuremath{'}}\ensuremath{\rightarrow}e\ensuremath{\nu}$ in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8$ TeV. The data used in the search represent 19.7 p${\mathrm{b}}^{--1}$ collected by the Collider Detector at Fermilab. Limits are placed on $\ensuremath{\sigma}B(p\overline{p}\ensuremath{\rightarrow}{W}^{\ensuremath{'}}\ensuremath{\rightarrow}e\ensuremath{\nu})$ as a function of ${M}_{{W}^{\ensuremath{'}}}$. Assuming standard couplings of the ${W}^{\ensuremath{'}}$ to fermions, we establish the limit ${M}_{{W}^{\ensuremath{'}}}&gt;652$ GeV ${/c}^{2}$ (95% C.L.).

We search for standard model single-top-quark production in the W-gluon fusion and W* channels using 106 pb^-1 of data from p-pbar collisions at sqrt(s)=1.8 TeV collected with the Collider Detector at Fermilab. We set an upper limit at 95% C.L. on the combined W-gluon fusion and W* single-top cross section of 14 pb, roughly six times larger than the standard model prediction. Separate 95% C.L. upper limits in the W-gluon fusion and W* channels are also determined and are found to be 13 and 18 pb, respectively.

We report a measurement of the strong coupling constant, alpha(s)(MZ), extracted from inclusive jet production in pp collisions at square root[s] = 1800 GeV. The QCD prediction for the evolution of alpha(s) with jet transverse energy ET is tested over the range 40<ET<450 GeV using ET for the renormalization scale. The data show good agreement with QCD in the region below 250 GeV. The value of alpha(s) at the mass of the Z0 boson averaged over the range 40<ET<250 GeV is found to be alpha(s)(MZ) = 0.1178+/-0.0001(stat)+0.0081(-0.0095)(expt. syst). The associated theoretical uncertainties are mainly due to the choice of renormalization scale ((+6%)(-4%)) and input parton distribution functions (5%).

The exclusive gammaE(T) signal has a small standard model cross section and is thus a channel sensitive to new physics. This signature is predicted by models with a superlight gravitino or with large extra spatial dimensions. We search for such signals at the Collider Detector at Fermilab, using 87 pb(-1) of data at square root [s]=1.8 TeV, and extract 95% C.L. limits on these processes. A limit of 221 GeV is set on the scale |F|(1/2) in supersymmetric models. For 4, 6, and 8 extra dimensions, model-dependent limits on the fundamental mass scale M(D) of 0.55, 0.58, and 0.60 TeV, respectively, are found. We also specify a "pseudo-model-independent" method of comparing the results to theoretical predictions.

We present a study of p¯p collisions at √s=1800 and 630 GeV collected using a minimum bias trigger by the CDF experiment in which the data set is divided into two classes corresponding to “soft” and “hard” interactions. For each subsample, the analysis includes measurements of the multiplicity, transverse momentum (pT) spectrum, and the average pT and event-by-event pT dispersion as a function of multiplicity. A comparison of results shows distinct differences in the behavior of the two samples as a function of the center of mass (c.m.) energy. We find evidence that the properties of the soft sample are invariant as a function of c.m. energy.Received 26 October 2001DOI:https://doi.org/10.1103/PhysRevD.65.072005©2002 American Physical Society

We present an analysis of data from p p\ifmmode\bar\else\textasciimacron\fi{} collisions at a center-of-mass energy of \ensuremath{\surd}s =1800 GeV. A measurement is made of the ratio R\ensuremath{\equiv}\ensuremath{\sigma}B(p p\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}W\ensuremath{\rightarrow}e\ensuremath{\nu})/\ensuremath{\sigma}B(p p\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}${\mathit{Z}}^{0}$\ensuremath{\rightarrow}ee). The data represent 19.6 ${\mathrm{pg}}^{\mathrm{\ensuremath{-}}1}$ collected by the Collider Detector at Fermilab during the 1992--1993 collider run of the Fermilab Tevatron. We find R=10.90\ifmmode\pm\else\textpm\fi{}0.32(stat)\ifmmode\pm\else\textpm\fi{}0.29(syst), and from this value we extract a measurement of the W\ensuremath{\rightarrow}e\ensuremath{\nu} branching ratio \ensuremath{\Gamma}(W\ensuremath{\rightarrow}e\ensuremath{\nu})/\ensuremath{\Gamma}(W)=0.1094\ifmmode\pm\else\textpm\fi{}0.0033(stat)\ifmmode\pm\else\textpm\fi{}0.0031(syst). From this branching ratio we set a limit on the top quark mass of ${\mathit{m}}_{\mathit{t}}$&gt;62 GeV/${\mathit{c}}^{2}$ at the 95% confidence level. In contrast with direct searches for the top quark, this limit makes no assumptions about the allowed decay modes of the top quark. In addition, we use a calculation of the leptonic width \ensuremath{\Gamma}(W\ensuremath{\rightarrow}e\ensuremath{\nu}) to obtain a value for the W total decay width: \ensuremath{\Gamma}(W)=2.064\ifmmode\pm\else\textpm\fi{}0.060(stat)\ifmmode\pm\else\textpm\fi{}0.059(syst) GeV.

We present a detailed description of a search for anomalous production of missing E T ( E T ), jets, leptons (e, µ, τ ), b-quarks, or additional photons in events containing two isolated, central (|η| < 1.0) photons with E T > 12 GeV.The results are consistent with standard model expectations, with the possible exception of one event that has in addition to the two photons a central electron, a high-E T electromagnetic cluster, and large E T .We set limits using two specific SUSY scenarios for production of diphoton events with E T .

We report on a search for the flavor-changing neutral current decays B^+ -> mu^+ mu^- K^+ and B^0 -> mu^+ mu^- K^{*0} using 88 pb^{-1} of data from p-pbar collisions at \sqrt{s}=1.8 TeV, collected with the Collider Detector at Fermilab. Finding no evidence for these decays, we set upper limits on the branching fractions B(B^+ -> mu^+ mu^- K^+) < 5.2x10^{-6} and B(B^0 -> mu^+ mu^-K^{*0}) < 4.0x10^{-6} at the 90% confidence level.

The decay Λ0b→J/ψ Λ is observed in 110 pb−1 of pp¯ collisions taken at √s=1.8 TeV. These data are used to measure a Λ0b mass of 5621±4(stat)±3(syst) MeV/c2, and a mass difference between the Λ0b and the B0 of 340±5(stat)±1(syst) MeV/c2. The production cross-section times branching fraction for the decay Λ0b→J/ψ Λ relative to that for the decay B0→J/ψ K0S has been measured to be 0.27±0.12(stat)±0.05(syst).Received 30 August 1996DOI:https://doi.org/10.1103/PhysRevD.55.1142©1997 American Physical Society

We report on measurements of differential µ -b cross sections, where the muon is from a semi-leptonic b decay and the b is identified using precision track reconstruction in jets.The semi-differential correlated cross sections, dσ/dE b T , dσ/dp b T , and dσ/dδφ(µ -b) for p µ T > 9 GeV/c, |η µ | < 0.6, E b T > 10 GeV, |η b | < 1.5, are presented and compared to next-to-leading order QCD calculations.

We present a measurement of the B0 B0-bar oscillation frequency using a flavor tagging method based on correlations of B meson flavor with the charge of other particles produced in p p-bar collisions at sqrt{s} = 1.8 TeV. Such correlations are expected to arise from b quark hadronization and from B** decays. We partially reconstruct B mesons using the semileptonic decays B0 -> lepton D(*)- X. and B+ -> lepton D0-bar X$. From the oscillation frequency, we obtain the mass difference between the two B0 mass eigenstates, Delta m_d = 0.471 {+0.078} {-0.068}(stat) +- 0.034 (syst) hbar ps-1, and measure the efficiency and purity of this flavor tagging method for both charged and neutral B mesons.

We report limits on anomalous ZZγ and Zγγ couplings derived from an analysis of Z+photon production based upon approximately 20pb−1 of the p¯p collision data recorded by the Collider Detector at Fermilab. We observe good agreement with the standard model expectation that all Zγ couplings are zero. Confidence level intervals for individual couplings and contours for pairs of CP-conserving/violating ZZγ and Zγγ couplings are presented.Received 9 September 1994DOI:https://doi.org/10.1103/PhysRevLett.74.1941©1995 American Physical Society

We use 106 pb (-1) of data collected with the Collider Detector at Fermilab to search for narrow-width, vector particles decaying to a top and an antitop quark. Model independent upper limits on the cross section for narrow, vector resonances decaying to t&tmacr; are presented. At the 95% confidence level, we exclude the existence of a leptophobic Z' boson in a model of top-color-assisted technicolor with mass M(Z')<480 GeV/c(2) for natural width gamma = 0.012M(Z'), and M(Z')<780 GeV/c(2) for gamma = 0.04M(Z').

We present searches for quark-lepton compositeness and a heavy W' boson at high electron-neutrino transverse mass. We use approximately 110 pb(-1) of data collected in p p macro collisions at square root of [s] = 1.8 TeV by the CDF Collaboration during 1992-1995. The data are consistent with standard model expectations. Limits are set on the quark-lepton compositeness scale Lambda, the ratio of partial cross sections sigma(W'-->enu)/sigma(W-->enu), and the mass of a W' boson with standard model couplings. We exclude Lambda<2.81 TeV and a W' boson with mass below 754 GeV/c(2) at the 95% confidence level. Combining with our previously published limit obtained using the muon channel, we exclude a W' boson with mass below 786 GeV/c(2) at the 95% confidence level.

Inclusive momentum distributions of charged particles in restricted cones around jet axes were measured in dijet events with invariant dijet masses in the range 80 to 600GeV/c2. Events were produced at the Fermilab Tevatron in pp¯ collisions with a center of mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The results were compared to perturbative QCD calculations carried out in the framework of the modified leading log approximation (MLLA) and assuming local parton-hadron duality. It was shown that the data follow theoretical predictions quite well over the whole range of the jet energies included in this analysis. We extracted the MLLA cutoff scale Qeff and found a value of 230±40MeV. The theoretical prediction of Ejetsinθc scaling, where θc is the cone opening angle, was experimentally observed for the first time. From the MLLA fits to the data, two more parameters were extracted: the ratio of parton multiplicities in gluon and quark jets, r=Npartonsg−jet/Npartonsq−jet=1.9±0.5, and the ratio of the number of charged hadrons to the number of predicted partons in a jet, KLPHDcharged=Nhadronscharged/Npartons=0.56±0.10. Received 24 May 2002DOI:https://doi.org/10.1103/PhysRevD.68.012003©2003 American Physical Society

We present the first evidence of charmless decays of the $B_s^0$ meson, the decay \phiphi, and a measurement of the Branching Ratio $\BR(\phiphi)$ using $180 {\rm pb}^{-1}$ of data collected by the \cdfii experiment at the Fermilab Tevatron collider. In addition, the BR and direct CP asymmetry for the \phik\ decay are measured. We obtain: $\BR (\phiphi) = (14 \ase{6}{5}(stat.) \pm 6(syst.)) \times 10^{-6}$, $\BR (\phik) = (7.6 \pm 1.3(stat.) \pm 0.6(syst.)) \times 10^{-6}$, and $\ACP(\phik) = -0.07 \pm 0.17 (stat.) \ase{0.03}{0.02} (syst.)$. Both decays are governed in the Standard Model by second order (penguin) $b \myto s\bar{s}s$ amplitudes.

We present results of a search for ${W}^{+}{W}^{\ensuremath{-}}$ production through the leptonic decay channel ${W}^{+}{W}^{\ensuremath{-}}\ensuremath{\rightarrow}{l}^{+}{l}^{\ensuremath{-}}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ in $\overline{p}p$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$. In a $108{\mathrm{pb}}^{\ensuremath{-}1}$ data sample recorded with the Collider Detector at Fermilab, five ${W}^{+}{W}^{\ensuremath{-}}$ candidates are found with an expected standard model background of $1.2\ifmmode\pm\else\textpm\fi{}0.3$ events. The ${W}^{+}{W}^{\ensuremath{-}}$ production cross section is measured to be $\ensuremath{\sigma}(\overline{p}p\ensuremath{\rightarrow}{W}^{+}{W}^{\ensuremath{-}}){\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}10.2}_{\ensuremath{-}5.1}^{+6.3}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.6(\mathrm{syst})\mathrm{pb}$, in agreement with the standard model prediction. Limits on $\mathrm{WW}\ensuremath{\gamma}$ and $\mathrm{WWZ}$ anomalous couplings are presented.

We report on a search for supersymmetry using dilepton events which complements the classic missing ${E}_{T}$ plus multijet analyses. Using $19{\mathrm{pb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ recorded with the Collider Detector at Fermilab we have searched for squarks and gluinos decaying into charginos and producing events with two leptons. We observe one candidate event. In comparison, the expected number of background events from standard model processes is $2.39\ifmmode\pm\else\textpm\fi{}0.63(\mathrm{stat}{)}_{\ensuremath{-}0.42}^{+0.77}(\mathrm{syst})$. Hence we set limits on gluino and squark production based on predictions from the supergravity inspired minimal supersymmetric extension of the standard model.

We present results from a measurement of double diffraction dissociation in pp collisions at the Fermilab Tevatron collider. The production cross section for events with a central pseudorapidity gap of width Deltaeta(0)>3 (overlapping eta = 0) is found to be 4.43+/-0.02(stat)+/-1.18(syst) mb [ 3.42+/-0.01(stat)+/-1.09(syst) mb] at square root of (s) = 1800[630] GeV. Our results are compared with previous measurements and with predictions based on Regge theory and factorization.