The kinematic properties of t t events are studied in the Wϩmultijet channel using data collected with the CDF detector during the 1992-1995 runs at the Fermilab Tevatron collider corresponding to an integrated luminosity of 109 pb Ϫ1 . Distributions of a variety of kinematic variables chosen to be sensitive to different aspects of t t production are compared with those expected from Monte Carlo calculations. A sample of 34 events rich in t t pairs is obtained by requiring at least one jet identified by the silicon vertex detector ͑SVX͒ as having a displaced vertex consistent with the decay of a b hadron. The data are found to be in good agreement with predictions of the leading order t t matrix element with color coherent parton shower evolution. ͓S0556-2821͑99͒04007-2͔
We have observed bottom-charm mesons via the decay mode B-c(+/-) --> J/psi l(+/-)v in 1.8 TeV p (p) over bar collisions using the CDF detector at the Fermilab Tevatron. A fit of background and signal contributions to the J/psi l mass distribution yielded 20.4(-5.5)(+6.2) 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(stat) +/- 0.13(syst) GeV/c(2) and the B-c(+) lifetime to be 0.46(-0.16)(+0.18)(stat) +/- 0.03(syst) ps. Our measured yield (production cross section times branching ratio) for B-c(+) --> J/psi l(+)v relative to that for B+ --> J/psi K+ is 0.132(-0.037)(+0.041)(stat) +/- 0.031 (syst)(-0.020)(+0.032)(lifetime)
We report the observation of bottom-charmed mesons B(c) in 1.8 TeV collisions using the CDF detector at the Fermilab Tevatron. The B(c) mesons were found through their semileptonic decays, B(c)(+/-) --> J/psi l(+/-)X. A fit to the J/psi l mass distribution yielded 20.4(-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 +/- 0.39 (stat.)+/-0.13 (syst) 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 tau(B(c)) = 0.46(-0.16)(+0.18) (stat)+/-0.03 (syst) ps. We also measured the ratio of production cross section times branching fraction for Bc+ --> J/psi l(+) nu relative to that for B(+) --> J/psi K(+) to be sigma(B(c)) X B(B(c) --> J/psi l nu)/sigma(B) X B(B-->J/psi K) = 0.132(-0.037)(+0.041) (stat)+/-0.031 (syst)(-0.020)(+0.032)(lifetime)
We describe a measurement of the charge asymmetry of leptons from W-boson decays in the rapidity range 0 less-than [y(iota)] < 2.5 using W --> e nu, mu nu events from 110 +/- 7 pb(-1) of data collected by the CDF detector during 1992-1995. 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(W)(2). The asymmetry predictions that use parton distribution functions obtained from previously published CDF data in the central rapidity region (0.0 less-than [y(iota)] less-than 1.1) do not agree with the new data in the large rapidity region ([y(iota)] greater-than 1.1)
The average bottom-hadron and individual B+, B-0, and B-s(0) meson lifetimes have been determined using decays with a J/psi --> u(+)u(-) the final state. The data sample consists of 110 pb(-1) of pp collisions at root 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/(psi + X, we obtain [tau(b)] = 1.533 +/- 0.015(stat)(-0.031)(+0.035) (syst) ps. For the B+ and B-0 meson lifetimes, we determine tau(B+) = 1.68 +/- 0.07(stat) +/- 0.02(syst) ps, tau(B-0) = 1.58 +/- 0.09(stat) +/- 0.02(syst) ps, and tau(B+)/tau(B-0) = 1.06 +/- 0.07(stat) +/- 0.02(syst). For the B-s(0) meson lifetime, we find tau(B-s(0)) = 1.34(-0.19)(+0.23)(stat) +/- 0.05(syst) ps
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