P. de Barbaro

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.

The NuTeV Collaboration has extracted the electroweak parameter sin(2)theta(W) from the measurement of the ratios of neutral current to charged current nu and (-)nu cross sections. Our value, sin(2)theta((on-shell))(W) = 0.2277 +/- 0.0013(stat) +/- 0.0009(syst), is 3 standard deviations above the standard model prediction. We also present a model independent analysis of the same data in terms of neutral-current quark couplings.

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 results of an electron-beam-dump search for neutral particles with masses in the range 1 to 15 MeV and lifetimes \ensuremath{\tau} between ${10}^{\mathrm{\ensuremath{-}}14}$ and ${10}^{\mathrm{\ensuremath{-}}10}$ s. No evidence was found for such an object. We fule out the existence of any 1.8-MeV pseudoscalar boson with \ensuremath{\tau}>8.2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}15}$ s and an absorption cross section in matter less than 1 mb per nucleon, and exclude \ensuremath{\tau}>1\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}14}$ s were its cross section to equal 50 mb per nucleon. In conjunction with measurements of the electron's anomalous magnetic moment, this experiment shows that the narrow positron peaks observed in heavy-ion collisions at the Gessellschaft fu\ifmmode\ddot\else\textasciidieresis\fi{}r Schwerionenforschung are not due to an elementary pseudoscalar.

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 report measurements of the proton form factors GEp and GMp extracted from elastic scattering in the range 1≤Q2≤3 (GeV/c)2 with total uncertainties < 15% in GEp and < 3% in GMp. Comparisons are made to theoretical models, including those based on perturbative QCD, vector-meson dominance, QCD sum rules, and diquark constituents in the proton. The results for GEp are somewhat larger than indicated by most theoretical parametrizations, and the ratios of the Pauli and Dirac form factors Q2(F2pF1p) are lower in value and demonstrate a weaker Q2 dependence than those predictions. A global extraction of the elastic form factors from several experiments in the range 0.1 0.1<Q2<10 (GeV/c)2 is also presented.Received 4 November 1993DOI:https://doi.org/10.1103/PhysRevD.49.5671©1994 American Physical Society

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 present measurements of the semi-inclusive cross sections for νμ- and ν¯μ-nucleon deep inelastic scattering interactions with two oppositely charged muons in the final state. These events dominantly arise from the production of a charm quark during the scattering process. The measurement was obtained from the analysis of 5102 νμ-induced and 1458 ν¯μ-induced events collected with the NuTeV detector exposed to a sign-selected beam at the Fermilab Tevatron. We also extract a cross-section measurement from a reanalysis of 5030 νμ-induced and 1060 ν¯μ-induced events collected from the exposure of the same detector to a quad-triplet beam by the Chicago Columbia Fermilab Rochester (CCFR) experiment. The results are combined to obtain the most statistically precise measurement of neutrino-induced dimuon production cross sections to date. These measurements should be of broad use to phenomenologists interested in the dynamics of charm production, the strangeness content of the nucleon, and the Cabibbo-Kobayashi-Maskawa matrix element Vcd. Received 21 February 2001DOI:https://doi.org/10.1103/PhysRevD.64.112006©2001 American Physical Society

We present an improved determination of the proton structure functions F2 and xF3 from the Columbia-Chicago-Fermilab-Rochester Collaboration ν−Fe deep inelastic scattering experiment. Comparisons to corrected high-statistics charged-lepton scattering results for F2 from the NMC, E665, SLAC, and BCDMS experiments indicate good agreement for x>0.1 but some discrepancy at lower x. The Q2 evolution of both the F2 and xF3 structure functions yields a value of the strong coupling constant at the scale of mass of the Z boson of αs(M2Z)=0.119±0.002(expt)±0.004(theory). This is one of the most precise measurements of this quantity.Received 30 January 1997DOI:https://doi.org/10.1103/PhysRevLett.79.1213©1997 American Physical Society

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 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 a measurement of neutrino tridents, muon pairs induced by neutrino scattering in the Coulomb field of a target nucleus, in the Columbia-Chicago-Fermilab-Rochester neutrino experiment at the Fermilab Tevatron. The observed number of tridents after geometric and kinematic corrections, 37.0\ifmmode\pm\else\textpm\fi{}12.4, supports the standard-model prediction of 45.3\ifmmode\pm\else\textpm\fi{}2.3 events. This is the first demonstration of the W-Z destructive interference from neutrino tridents, and rules out, at 99% C.L., the V-A prediction without the interference.

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

The NuTeV experiment at Fermilab has obtained a unique high statistics sample of neutrino and anti-neutrino interactions using its high-energy sign-selected beam. We present a measurement of the differential cross section for charged-current neutrino and anti-neutrino scattering from iron. Structure functions, F_2(x,Q^2) and xF_3(x,Q^2), are determined by fitting the inelasticity, y, dependence of the cross sections. This measurement has significantly improved systematic precision as a consequence of more precise understanding of hadron and muon energy scales.

We present new measurements of the inclusive forward-backward ttbar production asymmetry, AFB, and its dependence on several properties of the ttbar system. The measurements are performed with the full Tevatron data set recorded with the CDF II detector during ppbar collisions at sqrt(s) = 1.96 TeV, corresponding to an integrated luminosity of 9.4 fb^(-1). We measure the asymmetry using the rapidity difference Delta-y=y_(t)-y_(tbar). Parton-level results are derived, yielding an inclusive asymmetry of 0.164+/-0.047 (stat + syst). We observe a linear dependence of AFB on the top-quark pair mass M(ttbar) and the rapidity difference |Delta-y| at detector and parton levels. Assuming the standard model, the probabilities to observe the measured values or larger for the detector-level dependencies are 7.4*10^(-3) and 2.2*10^(-3) for M(ttbar) and |Delta-y| respectively. Lastly, we study the dependence of the asymmetry on the transverse momentum of the ttbar system at the detector level. These results are consistent with previous lower-precision measurements and provide additional quantification of the functional dependencies of the asymmetry.

We have measured the W-boson mass MW using data corresponding to 2.2/fb of integrated luminosity collected in proton-antiproton collisions at 1.96 TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470126 W->enu candidates and 624708 W->munu candidates yield the measurement MW = 80387 +- 12 (stat) +- 15 (syst) = 80387 +- 19 MeV. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined.

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.

A high-statistics study by the Columbia-Chicago-Fermilab-Rochester Collaboration of opposite-sign dimuon events induced by neutrino-nucleon scattering at the Fermilab Tevatron is presented. A sample of 5044 νμ and 1062 ν¯μ induced μ∓μ± events with Pμ1≥9 GeV/c, Pμ2≥5 GeV/c, 30≤Eν≤600 GeV, and 〈Q2〉=22.2 GeV2/c2 is observed. The data support the slow-rescaling model of charm production with a value of mc=1.31±0.24 GeV2/c2. The first measurement of the Q2 dependence of the nucleon strange quark distribution xs(x) is presented. The data yield the Cabibbo-Kobayashi-Maskawa matrix element ‖Vcd‖=0.209±0.012 and the nucleon fractional strangeness content ηs=0.064−0.007+0.008.Received 4 August 1992DOI:https://doi.org/10.1103/PhysRevLett.70.134©1993 American Physical Society

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.

A search for neutral heavy leptons (NHLs) has been performed using an instrumented decay channel at the NuTeV (E-815) experiment at Fermilab. The data were examined for NHLs decaying into muonic final states ( μμν, μeν, μπ, and μρ); no evidence has been found for NHLs in the 0.25–2.0 GeV mass range. This analysis places limits on the mixing of NHLs with standard light neutrinos at a level up to an order of magnitude more restrictive than previous search limits in this mass range.Received 4 August 1999DOI:https://doi.org/10.1103/PhysRevLett.83.4943©1999 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

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.

Received 17 April 2003DOI:https://doi.org/10.1103/PhysRevLett.90.239902©2003 American Physical Society

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.

The CDF Plug Upgrade calorimeter, which fully exploits the tile–fiber technique, was tested at the Fermilab meson beamline. The calorimeter was exposed to positron, positively charged pion and positive muon beams with energies in the range of 5–230GeV. The energy resolution of the electromagnetic calorimeter to the positron beam is consistent with the design value of 16%/E⊕1%, where E is the energy in units of GeV and ⊕ represents sum in quadrature. The non-linearity for positrons is studied in an energy range of 11–181GeV. It is important to incorporate the response of the preshower detector, the first layer of the electromagnetic calorimeter which is readout separately, into that of the calorimeter to reduce the non-linearity to 1% or less. The energy scale is about 1.46pC/GeV with HAMAMATSU R4125 operated typically at a gain of 2.5×104. The response non-uniformity over the surface of a tower of the electromagnetic calorimeter is found to be about 2% with 57GeV positrons. Studies of several detailed detector characteristics are also presented.

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 present a new measurement of the difference between the nucleon strange and antistrange quark distributions from dimuon events recorded by the NuTeV experiment at Fermilab. This analysis is the first to use a complete next to leading order QCD description of charm production from neutrino scattering. Dimuon events in neutrino deep inelastic scattering allow direct and independent study of the strange and antistrange content of the nucleon. We find a positive strange asymmetry with a significance of 1.6σ. We also report a new measurement of the charm mass.Received 25 March 2007DOI:https://doi.org/10.1103/PhysRevLett.99.192001©2007 American Physical Society

We report a measurement of the difference (Delta Acp) between time-integrated CP--violating asymmetries in D0-> K+ K- and D0-> pi+pi- decays reconstructed in the full data set of proton-antiproton collisions collected by the Collider Detector at Fermilab, corresponding to 9.7 fb-1 of integrated luminosity. The strong decay D*+->D0 pi+ is used to identify the charm meson at production as D0 or anti-D0. We measure Delta Acp = [-0.62 +- 0.21 (stat) +- 0.10 (syst)] %, which differs from zero by 2.7 Gaussian standard deviations.This result supports similar evidence for CP violation in charm-quark decays obtained in proton-proton collisions.

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.

We report on a measurement of CP-violating asymmetries (Acp) in the Cabibbo-suppressed D0 --> pi+ pi- and D0 --> K+K- decays reconstructed in a data sample corresponding to 5.9 fb-1 of integrated luminosity collected by the upgraded Collider Detector at Fermilab. We use the strong decay D*+ --> D0 pi+ to identify the flavor of the charmed meson at production and exploit CP-conserving strong c-cbar pair-production in p-pbar collisions. High-statistics samples of Cabibbo-favored D0 --> K- p+ decays with and without a D* tag are used to correct for instrumental effects and significantly reduce systematic uncertainties. We measure Acp(D0 --> pi+ pi-) = (+0.22 +- 0.24 (stat) +- 0.11 (syst))% and Acp(D 0 --> K+ K-) = (-0.24 +- 0.22 (stat) +- 0.09 (syst))%, in agreement with CP conservation. These are the most precise determinations from a single experiment to date. Under the assumption of negligible direct CP violation in D0 --> pi+ pi- and D0 --> K+K- decays, the results provide an upper limit to the CP-violating asymmetry in D0 mixing, |Acp^{ind}(D0)|< 0.13% at the 90% confidence level.

We present the results of a search for dark matter production in the monojet signature. We analyze a sample of Tevatron $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ corresponding to an integrated luminosity of $6.7\text{ }\text{ }\mathrm{f}{\mathrm{b}}^{\ensuremath{-}1}$ recorded by the CDF II detector. In events with large missing transverse energy and one energetic jet, we find good agreement between the standard model prediction and the observed data. We set 90% confidence level upper limits on the dark matter production rate. The limits are translated into bounds on nucleon-dark matter scattering rates which are competitive with current direct detection bounds on spin-independent interaction below a dark matter candidate mass of $5\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, and on spin-dependent interactions up to masses of $200\text{ }\text{ }\mathrm{GeV}/{c}^{2}$.

Using the full CDF Run II data sample, we report evidence for a new resonance, which we refer to as $B(5970)$, found simultaneously in the ${B}^{0}{\ensuremath{\pi}}^{+}$ and ${B}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ mass distributions with a significance of 4.4 standard deviations. We further report the first study of resonances consistent with orbitally excited ${B}^{+}$ mesons and an updated measurement of the properties of orbitally excited ${B}^{0}$ and ${B}_{s}^{0}$ mesons. We measure the masses and widths of all states, as well as the relative production rates of the ${B}_{1}$, ${B}_{2}^{*}$, and $B(5970)$ states and the branching fraction of the ${B}_{s2}^{*0}$ state to either ${B}^{*+}{K}^{\ensuremath{-}}$ and ${B}^{+}{K}^{\ensuremath{-}}$. Furthermore, we measure the production rates of the orbitally excited ${B}^{0,+}$ states relative to the ${B}^{0,+}$ ground state. The masses of the new $B(5970)$ resonances are $5978\ifmmode\pm\else\textpm\fi{}5(\text{stat})\ifmmode\pm\else\textpm\fi{}12(\text{syst})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ for the neutral state and $5961\ifmmode\pm\else\textpm\fi{}5(\text{stat})\ifmmode\pm\else\textpm\fi{}12(\text{syst})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ for the charged state, assuming that the resonance decays into $B\ensuremath{\pi}$ final states. The properties of the orbitally excited and the new $B(5970{)}^{0,+}$ states are compatible with isospin symmetry.

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.

The NuTeV Collaboration recently reported a value of ${\mathrm{sin}}^{2}{\ensuremath{\theta}}_{W}$ measured in neutrino-nucleon scattering that is 3 standard deviations above the standard model prediction. This result is derived assuming that (1) the strange sea is quark-antiquark symmetric, $s(x)=\overline{s}(x),$ and (2) up and down quark distributions are symmetric under the simultaneous interchange of $u\ensuremath{\leftrightarrow}d$ and $p\ensuremath{\leftrightarrow}n.$ We report the impact of violations of these symmetries on ${\mathrm{sin}}^{2}{\ensuremath{\theta}}_{W}$ and discuss the theoretical and experimental constraints on such asymmetries.

We report on the extraction of the structure functions F2 and DeltaxF(3) = xF(nu)(3)-xF(nu;)(3) from CCFR nu(mu)-Fe and nu;(mu)-Fe differential cross sections. The extraction is performed in a physics model-independent (PMI) way. This first measurement of DeltaxF(3), which is useful in testing models of heavy charm production, is higher than current theoretical predictions. The ratio of the F2 (PMI) values measured in nu(mu) and mu scattering is in agreement (within 5%) with the predictions of next-to-leading-order parton distribution functions using massive charm production schemes, thus resolving the long-standing discrepancy between the two sets of data.

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 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 report results on a precision measurement of the ratio R = uLIUT in deep inelastic electronnucleon scattering in the kinematic range 0.2 ~ x ~ 0.5 and 1 ~ Q 2 ~ 10 ( Ge VIc ) 2 • Our results show, for the first time, a clear falloff of R with increasing Q 2 • Our R results are in agreement with QCD predictions only when corrections for target mass effects and some additional higher twist effects are included.At small x, the data on R favor structure functions with a large gluon contribution.We also report results on the differences RA -RD and the cross section ratio uA I uD between Fe and Au nuclei and the deuteron.Our results for RA -RD are consistent with zero for all x, Q 2 indicating that possible contributions to R from nuclear higher twist effects and spin-0 constituents in nuclei are not different from those in nucleons.The ratios uA I uD from all recent experiments, at all x, Q 2 values, are now in agreement.

We measured the differences in $R=\frac{{\ensuremath{\sigma}}_{L}}{{\ensuremath{\sigma}}_{T}}$ and the cross-section ratio $\frac{{\ensuremath{\sigma}}^{A}}{{\ensuremath{\sigma}}^{D}}$ in deep-inelastic electron scattering from D, Fe, and Au nuclei in the kinematic range $0.2\ensuremath{\le}x\ensuremath{\le}0.5$ and $1\ensuremath{\le}{Q}^{2}\ensuremath{\le}5$ ${(\mathrm{G}\mathrm{e}\mathrm{v}/\mathit{c})}^{2}$. Our results for ${R}^{A}\ensuremath{-}{R}^{D}$ are consistent with zero for all $x$ and ${Q}^{2}$, indicating that possible contributions to $R$ from nuclear higher-twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The European Muon Collaboration effect is reconfirmed, and the low-$x$ data from all recent experiments, at all ${Q}^{2}$, are now in agreement.

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 report on the test beam results and calibration methods using high energy electrons, pions and muons with the CMS forward calorimeter (HF). The HF calorimeter covers a large pseudorapidity region ( $3\leq|\eta|\leq5$ ), and is essential for a large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels in Higgs production. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h≈5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as $\frac{a}{\sqrt{E}}\oplus{b}$ . The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%.

We present a precision measurement of the top-quark mass using the full sample of Tevatron $\sqrt{s}=1.96$ TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 $fb^{-1}$. Using a sample of $t\bar{t}$ candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the $W$ boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with {\it in situ} calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, $\mtop = 172.85 $\pm$ 0.71 (stat) $\pm$ 0.85 (syst) GeV/c^{2}.$

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 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 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 .

The CCFR Collaboration presents a measurement of scaling violations of the nonsinglet structure function and a comparison to the predictions of perturbative QCD. The value of ${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{QCD}}$, from the nonsinglet evolution with ${\mathit{Q}}^{2}$&gt;15 ${\mathrm{GeV}}^{2}$ and in the modified minimal-subtraction renormalization scheme, is found to be 210\ifmmode\pm\else\textpm\fi{}28(stat)\ifmmode\pm\else\textpm\fi{}41(syst) MeV.

We extract a set of values for the Gross–Llewellyn Smith sum rule at different values of 4-momentum transfer squared ( Q2), by combining revised CCFR neutrino data with data from other neutrino deep-inelastic scattering experiments for 1<Q2<15GeV2/c2. A comparison with the order α3s theoretical predictions yields a determination of αs at the scale of the Z-boson mass of 0.114±0.0090.012. This measurement provides a new and useful test of perturbative QCD at low Q2, because of the low uncertainties in the higher order calculations.Received 8 May 1998DOI:https://doi.org/10.1103/PhysRevLett.81.3595©1998 American Physical Society

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.

Limits on $\nu_\mu (\overline{\nu}_\mu) \to \nu_e (\overline{\nu}_e)$ oscillations based on a statistical separation of $\nu_e N$ charged current interactions in the CCFR detector at Fermilab are presented. $\nu_e$ interactions are identified by the difference in the longitudinal shower energy deposition pattern of $\nu_e N \rightarrow eX$ versus $\nu_\mu N \to \nu_\mu X$ interactions. Neutrino energies range from 30 to 600 GeV with a mean of 140 GeV, and $\nu_\mu$ flight lengths vary from 0.9 km to 1.4 km. The lowest 90% confidence upper limit in $sin^2 2\alpha$ of $1.1 \times 10^{-3}$ is obtained at $\Delta m^2 \sim 300 eV^2$. For $sin^2 2\alpha = 1$, $\Delta m^2 > 1.6 eV^2$ is excluded, and for $\Delta m^2 \gg 1000 eV^2$, $sin^2 2\alpha > 1.8 \times 10^{-3}$ is excluded. This result is the most stringent limit to date for $\Delta m^2 > 25 eV^2$ and it excludes the high $\Delta m^2$ oscillation region favoured by the LSND experiment. The $\nu_\mu$-to-$\nu_e$ cross-section ratio was measured as a test of $\nu_\mu (\bar\nu_\mu) \leftrightarrow \nu_e (\bar\nu_e)$ universality to be $1.026 \pm 0.055$.

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.

We report a measurement of the Gross-Llewellyn Smith sum rule: ∫(1x)dx xF3(x, Q2=3 GeV2)=2.50±0.018(stat.) ±0.078(syst.).

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 report new results on a precision measurement of the ratio $R=\frac{{\ensuremath{\sigma}}_{L}}{{\ensuremath{\sigma}}_{T}}$ and the structure function ${F}_{2}$ for deep-inelastic electron-nucleon scattering in the kinematic range $0.2\ensuremath{\le}x\ensuremath{\le}0.5$ and $1\ensuremath{\le}{Q}^{2}\ensuremath{\le}10$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$. Our results show, for the first time, a clear falloff of $R$ with increasing ${Q}^{2}$. Our $R$ and ${F}_{2}$ results are in good agreement with QCD predictions only when corrections for target-mass effects are included.

The transverse momentum cross section of ${e}^{+}{e}^{\ensuremath{-}}$ pairs in the $Z$-boson mass region of $66--116\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ is precisely measured using Run II data corresponding to $2.1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity recorded by the Collider Detector at Fermilab. The cross section is compared with two quantum chromodynamic calculations. One is a fixed-order perturbative calculation at $\mathcal{O}({\ensuremath{\alpha}}_{s}^{2})$, and the other combines perturbative predictions at high transverse momentum with the gluon resummation formalism at low transverse momentum. Comparisons of the measurement with calculations show reasonable agreement. The measurement is of sufficient precision to allow refinements in the understanding of the transverse momentum distribution.

The angular distributions of muons from Υ(1S,2S,3S) → μ+ μ- decays are measured using data from pp collisions at sqrt[s] = 1.96 TeV corresponding to an integrated luminosity of 6.7 fb(-1) and collected with the CDF II detector at the Fermilab Tevatron. This analysis is the first to report the full angular distributions as functions of transverse momentum p(T) for Υ mesons in both the Collins-Soper and s-channel helicity frames. This is also the first measurement of the spin alignment of Υ(3S) mesons. Within the kinematic range of Υ rapidity |y|<0.6 and p(T) up to 40 GeV/c, the angular distributions are found to be nearly isotropic.

We report final measurements of direct $\mathit{CP}$--violating asymmetries in charmless decays of neutral bottom hadrons to pairs of charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using the complete $\sqrt{s}=1.96$ TeV proton-antiproton collisions data set, corresponding to 9.3 fb$^{-1}$ of integrated luminosity, we measure $\mathcal{A}(\Lambda^0_b \rightarrow p\pi^{-}) = +0.06 \pm 0.07\mathrm{(stat)} \pm 0.03\mathrm{(syst)}$ and $\mathcal{A}(\Lambda^0_b \rightarrow pK^{-}) = -0.10 \pm 0.08\mathrm{(stat)} \pm 0.04\mathrm{(syst)}$, compatible with no asymmetry. In addition we measure the $\mathit{CP}$--violating asymmetries in $B^0_s \rightarrow K^{-}\pi^{+}$ and $B^0 \rightarrow K^{+}\pi^{-}$ decays to be $\mathcal{A}(B^0_s \rightarrow K^{-}\pi^{+}) = +0.22 \pm 0.07\mathrm{stat)} \pm 0.02\mathrm{(syst)}$ and $\mathcal{A}(B^0 \rightarrow K^{+}\pi^{-}) = -0.083\pm 0.013 \mathrm{(stat)} \pm 0.004\mathrm{(syst)}$, respectively, which are significantly different from zero and consistent with current world averages.

We measure the inclusive forward-backward asymmetry of the charged-lepton pseudorapidities from top-quark pairs produced in proton-antiproton collisions and decaying to final states that contain two charged leptons (electrons or muons). The data are collected with the Collider Detector at Fermilab and correspond to an integrated luminosity of 9.1 fb(-1). We measure the leptonic forward-backward asymmetry, A(FB)(ℓ), to be 0.072 ± 0.060 and the leptonic pair forward-backward asymmetry, A(FB)(ℓℓ), to be 0.076 ± 0.082. The measured values can be compared with the standard model predictions of A(FB)(ℓ) = 0.038 ± 0.003 and A(FB)(ℓℓ) = 0.048 ± 0.004, respectively. Additionally, we combine the A(FB)(ℓ) result with a previous determination from a final state with a single lepton and hadronic jets and obtain A(FB)(ℓ) = 0.090(-0.026)(+0.028).

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 $176.0\ifmmode\pm\else\textpm\fi{}6.5\mathrm{GeV}{/c}^{2}$.

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.

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 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.

The techniques used to calibrate and monitor the energy response of the CCFR (Lab E) iron-scintillator target calorimeter for a precision measurement of shower energies are described. Measurements on the energy response of the calorimeter to hadrons, electrons, and minimum ionizing muons (from range outs) are presented. The calorimeter's energy response and resolution for hadrons and electrons are obtained using a test beam with energies between 15 and 450 GeV.

Extensive measurements have been made with pions, electrons and muons on four production wedges of the compact muon solenoid (CMS) hadron barrel (HB) calorimeter in the H2 beam line at CERN with particle momenta varying from 20 to 300 GeV/c. The time structure of the events was measured with the full chain of preproduction front-end electronics running at 34 MHz. Moving-wire radioactive source data were also collected for all scintillator layers in the HB. The energy dependent time slewing effect was measured and tuned for optimal performance.

We present a measurement of the \CP-violating parameter \betas using approximately 6500 $\BsJpsiPhi$ decays reconstructed with the CDF\,II detector in a sample of $p\bar p$ collisions at $\sqrt{s}=1.96$ TeV corresponding to 5.2 fb$^{-1}$ integrated luminosity produced by the Tevatron Collider at Fermilab. We find the \CP-violating phase to be within the range $\betas \in [0.02, 0.52] \cup [1.08, 1.55]$ at 68% confidence level where the coverage property of the quoted interval is guaranteed using a frequentist statistical analysis. This result is in agreement with the standard model expectation at the level of about one Gaussian standard deviation. We consider the inclusion of a potential $S$-wave contribution to the $\Bs\to J/\psi K^+K^-$ final state which is found to be negligible over the mass interval $1.009 < m(K^+K^-)<1.028 \gevcc$. Assuming the standard model prediction for the \CP-violating phase \betas, we find the \Bs decay width difference to be $\deltaG = 0.075 \pm 0.035\,\textrm{(stat)} \pm 0.006\,\textrm{(syst)} \ps$. We also present the most precise measurements of the \Bs mean lifetime $\tau(\Bs) = 1.529 \pm 0.025\,\textrm{(stat)} \pm 0.012\,\textrm{(syst)}$ ps, the polarization fractions $|A_0(0)|^2 = 0.524 \pm 0.013\,\textrm{(stat)} \pm 0.015\,\textrm{(syst)}$ and $|A_{\parallel}(0)|^2 = 0.231 \pm 0.014\,\textrm{(stat)} \pm 0.015\,\textrm{(syst)}$, as well as the strong phase $\delta_{\perp}= 2.95 \pm 0.64\,\textrm{(stat)} \pm 0.07\,\textrm{(syst)} \textrm{rad}$. In addition, we report an alternative Bayesian analysis that gives results consistent with the frequentist approach.

We search for annihilation decay modes of neutral $b$ mesons into pairs of charmless charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using a data sample corresponding to 6 fb$^{-1}$ of integrated luminosity, we obtain the first evidence for the $B^0_s \to \pi^+\pi^-$ decay, with a significance of $3.7\sigma$, and a measured branching ratio $\mathcal{B}(B^0_s \to \pi^+\pi^-)= (0.57 \pm 0.15 (stat) \pm 0.10 (syst))\times 10^{-6}$. A search for the $B^0 \to K^+K^-$ mode in the same sample yields a significance of $2.0\sigma$, and a central value estimate $\mathcal{B}(B^0 \to K^+K^-)= (0.23 \pm 0.10 (stat) \pm 0.10 (syst))\times 10^{-6}$.

Using data from proton-antiproton collisions at Ecms=1.96 TeV recorded by the CDF II detector at the Fermilab Tevatron, evidence for the excited resonance state Lambda_b* is presented in its Lambda_b0 pi+ pi- decay, followed by the Lambda_b0 -->Lambda_c+ (-->proton K- pi+) pi- decays. The analysis is based on a data sample corresponding to an integrated luminosity of 9.6/fb collected by an online event selection based on charged-particle tracks displaced from the proton-antiproton interaction point. The significance of the observed signal is 3.5 Gaussian sigmas. The mass of the observed state is found to be 5919.22 +- 0.76 MeV in agreement with similar findings in proton-proton collision experiments.

We present a measurement of the total decay width of the top quark using events with top-antitop-quark pair candidates reconstructed in the final state with one charged lepton and four or more hadronic jets. We use the full Tevatron Run II data set of $\sqrt{s} = 1.96$ TeV proton-antiproton collisions recorded by the CDF II detector. The top-quark mass and the mass of the hadronically-decaying $W$ boson are reconstructed for each event and compared with distributions derived from simulated signal and background samples to extract the top-quark width (\gmt) and the energy scale of the calorimeter jets with {\it in-situ} calibration. For a top-quark mass $\mtop = \gevcc{172.5}$, we find $1.10<\gmt<\gev{4.05}$ at 68% confidence level, which is in agreement with the standard-model expectation of \gev{1.3} and is the most precise direct measurement of the top-quark width to date.

This Letter reports a measurement of the cross section for producing pairs of central prompt isolated photons in proton-antiproton collisions at a total energy of 1.96 TeV using data corresponding to 9.5/fb integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. The measured differential cross section is compared to three calculations derived from the theory of strong interactions. These include a prediction based on a leading order matrix element calculation merged with parton shower, a next-to-leading order, and a next-to-next-to-leading order calculation. The first and last calculations reproduce most aspects of the data, thus showing the importance of higher-order contributions for understanding the theory of strong interaction and improving measurements of the Higgs boson and searches for new phenomena in diphoton final states.

We measure the asymmetry in the charge-weighted rapidity of the lepton in semileptonic ttbar decays recorded with the CDF II detector using the full Tevatron Run II sample, corresponding to an integrated luminosity of 9.4/fb. A parametrization of the asymmetry as a function of the charge-weighted rapidity is used to correct for the finite acceptance of the detector and recover the production-level asymmetry. The result of afb(lep) = 0.094 +0.032 -0.029 is to be compared to the standard model next-to-leading-order prediction of afb(lep) = 0.038 +-0.003.

We study charged particle production in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta-phi space; toward, away, and transverse. The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the underlying event. The transverse region is divided into a MAX and MIN transverse region, which helps separate the hard component (initial and final-state radiation) from the beam-beam remnant and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

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.