We present a measurement of the forward-backward charge asymmetry of the process pp¯→Z0/γ+X,Z0/γ→e+e− at Mee>MZ, using 110pb−1 of data at s=1.8TeV collected at the Collider Detector at Fermilab. The measured charge asymmetries are 0.43±0.10 in the invariant mass region Mee>105GeV/c2, and 0.070±0.016 in the region 75<Mee<105GeV/c2. These results are consistent with the standard model values of 0.528±0.009 and 0.052±0.002, respectively.
The forward-backward asymmetry resuts from angular differential cross section : D(SIG)/D(COS(THETA*) = A*(1 + COS(THETA*)**2) + B*COS(THETA*), where THETA * is the emission angle of the E- relative to the quark momentum in the rest frame of the E+ E- pair.
We report on a measurement of the branching fraction of the Cabibbo-suppressed decay Bu+→J/ψπ+, where J/ψ→μ+μ−. The data were collected by the Collider Detector at Fermilab during 1992–1995 and correspond to an integrated luminosity of 110pb−1 in p¯p collisions at s=1.8TeV. A signal of 28−9+10 events is observed and we determine the ratio of branching fractions B(Bu+→J/ψπ+)/B(Bu+→J/ψK+) to be [5.0−1.7+1.9(stat)±0.1(syst)]%. Using the world average value for B(Bu+→J/ψK+), we calculate the branching fraction B(Bu+→J/ψπ+) to be (5.0−1.9+2.1)×10−5. We also search for the decay Bc+→J/ψπ+ and report a 95% confidence level limit on σ(Bc+)B(Bc+→J/ψπ+)/σ(Bu+)B(Bu+→J/ψK+) as a function of the Bc+ lifetime.
The ratio of the cross sections times the branching fraction.
We report on a study of the dijet invariant-mass distribution in events with one identified lepton, a significant imbalance in the total event transverse momentum, and two jets. This distribution is sensitive to the possible production of a new particle in association with a $W$ boson, where the boson decays leptonically. We use the full data set of proton-antiproton collisions at 1.96 TeV center-of-mass energy collected by the Collider Detector at the Fermilab Tevatron and corresponding to an integrated luminosity of 8.9 fb$^{-1}$. The data are found to be consistent with standard-model expectations, and a 95$\%$ confidence level upper limit is set on the cross section for a $W$ boson produced in association with a new particle decaying into two jets.
The extracted cross section assuming that the new contribution (the excess over the expected background) has the same acceptance as that for a 140 GeV Higgs boson produced in association with a W boson.
The extracted cross section measured with a restriction on DELTAR(JET1 JET2) and assuming that the new contribution (the excess over the expected background) has the same acceptance as that for a 140 GeV Higgs boson produced in association with a W boson.
The charmonium χ states are observed in both π− and p Be interactions near 200 GeV/c via their radiative decay into J/ψ. The χ(3510) and χ(3555) are produced with roughly equal cross sections in π− collisions while the χ(3555) dominates in p collisions. Simple gluon fusion can account for χ production with incident protons but additional mechanisms are needed for incident π−.
No description provided.
The dijet invariant mass distribution has been measured in the region between 120 and 1000 GeV/c2, in 1.8-TeV pp¯ collisions. The data sample was collected with the Collider Detector at Fermilab (CDF). Data are compared to leading order (LO) and next-to-leading order (NLO) QCD calculations using two different clustering cone radii R in the jet definition. A quantitative test shows good agreement of data with the LO and NLO QCD predictions for a cone of R=1. The test using a cone of R=0.7 shows less agreement. The NLO calculation shows an improvement compared to LO in reproducing the shape of the spectrum for both radii, and approximately predicts the cone size dependence of the cross section.
Observed cross section using R = 1.0. The second systematic error is the theoretical uncertainty and includes only the effect of the out-of-cone losses, the underlying event energy, and the contribution of multi-jet events.
Observed cross section using R = 0.7. The second systematic error is the theoretical uncertainty and includes only the effect of the out-of-cone losses, the underlying event energy, and the contribution of multi-jet events.
The first prompt photon measurement from the CDF experiment at the Fermilab pp¯ Collider is presented. Two independent methods are used to measure the cross section: one for high transverse momentum (PT) and one for lower PT. Comparisons to various theoretical calculations are shown. The cross section agrees qualitatively with QCD calculations but has a steeper slope at low PT.
Cross section using profile method and an isolation cut of 2 GeV in a cone around the photon. There is an additional 27 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
Cross section using conversion method and an isolation cut of 2 GeV in a cone around the photon. There is an additional +32,-46 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
Cross section using profile method and an isolation cut of 15 pct of the photon PT in a cone around the photon. There is an additional 29 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
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.
Final results (systematic errors included).
Final results (systematic errors included).
Statistical errors only. Data supplied by S. Belforte.
A measurement of the QCD jet-broadening parameter 〈QT〉 is described for high-ET jet data in the central calorimeter of the Collider Detector at Fermilab. As an alternate approach to clustering analysis, this method involves the use of a global event parameter which is free from the ambiguities associated with the definition and separation of individual clusters. The parameter QT is defined as the scalar sum of the transverse momentum perpendicular to the transverse thrust axis. Parton-level QCD predictions are made for 〈QT〉 as a function of ET, the total transverse energy in the events, and suggest that a measurement would show a dependence on the running of the strong coupling constant αs. Comparisons are made to first-order QCD parton-level calculations, as well as to fully evolved and hadronized leading-log simulations. The data are well described by the QCD predictions.
A small asymmetry in the systematic uncertainty has been ignored. Given here are the average values.
The inclusive cross section for J/ψ production times the branching ratio B(J/ψ→μ+μ−) has been measured in the forward pseudorapidity region: B×dσ[p¯+p→J/ψ(pT>10GeV/c,2.1<|η|<2.6)+X]/dη=192±9(stat)±29(syst)pb. The results are based on 74.1±5.2pb−1 of data collected by the CDF Collaboration at the Fermilab Tevatron Collider. The measurements extend earlier measurements of the D0 Collaboration to higher pTJ/ψ. In the kinematic range where the experiments partially overlap, these data are in good agreement with previous measurements.
The integrated cross section for J/PSI --> MU+ MU- decay.
Cross section as a function of PT. Statistical errors only.
We present a new measurement of the inclusive and differential production cross sections of $J/\psi$ mesons and $b$-hadrons in proton-antiproton collisions at $\sqrt{s}=1960$ GeV. The data correspond to an integrated luminosity of 39.7 pb$^{-1}$ collected by the CDF Run II detector. We find the integrated cross section for inclusive $J/\psi$ production for all transverse momenta from 0 to 20 GeV/$c$ in the rapidity range $|y|<0.6$ to be $4.08 \pm 0.02 (stat)^{+0.36}_{-0.33} (syst) \mu {\rm b}$. We separate the fraction of $J/\psi$ events from the decay of the long-lived $b$-hadrons using the lifetime distribution in all events with $p_T(J/\psi) > 1.25$ GeV/$c$. We find the total cross section for $b$-hadrons, including both hadrons and anti-hadrons, decaying to $J/\psi$ with transverse momenta greater than 1.25 GeV/$c$ in the rapidity range $|y(J/\psi)|<0.6$, is $ 0.330 \pm 0.005 (stat) ^{+0.036}_{-0.033} (syst) ~\mu{\rm b}$. Using a Monte Carlo simulation of the decay kinematics of $b$-hadrons to all final states containing a $J/\psi$, we extract the first measurement of the total single $b$-hadron cross section down to zero transverse momentum at $\sqrt{s}=1960$ GeV. We find the total single $b$-hadron cross section integrated over all transverse momenta for $b$-hadrons in the rapidity range $|y|<0.6$ to be $ 17.6 \pm 0.4 (stat)^{+2.5}_{-2.3} (syst) \mu{\rm b}$.
Integrated J/PSI cross section shown both uncorrected and corrected for branching ratio (5.88+-0.10PCT) of J/PSI into mu+mu-. Systematic error includes pT-dependent and fully correlated errors added in quadrature.
Differential cross section times branching ratio (5.88+-0.10PCT) into mu+mu- as a function of transverse momentum for the rapidity range -0.6 to 0.6 at a centre-of-mass energy of 1960 GeV.
Integrated bottom-hadron prouction cross section shown both uncorrected andcorrected for branching ratio (5.88+-0.10PCT) of J/PSI into mu+mu-. Systematic error includes pT-dependent and fully correlated errors added in quadrature.
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