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)
This paper reports an updated measurement of the standard model CP violation parameter sin 2 using the CDF Detector at Fermilab. The entire run I data sample of 110 pb Ϫ1 of proton-antiproton collisions at ͱs ϭ1.8 TeV is used to identify a signal sample of ϳ400 B→J/ K S 0 events, where J/→ ϩ Ϫ and K S 0 → ϩ Ϫ. 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 sin 2ϭ0.79 Ϫ0.44 ϩ0.41 (statϩsyst). This value of sin 2 is consistent with the standard model prediction, based upon existing measurements, of a large positive CP-violating asymmetry in this decay mode.
T. AFFOLDER et al.PHYSICAL REVIEW D 65 052006
052006-2We have searched for evidence of physics beyond the standard model in events that include an energetic photon and an energetic b-quark jet, produced in 85 pb Ϫ1 of p p collisions at 1.8 TeV at the Tevatron Collider at Fermilab. This signature, containing at least one gauge boson and a third-generation quark, could arise in the production and decay of a pair of new particles, such as those predicted by supersymmetry, leading to a production rate exceeding standard model predictions. We also search these events for anomalous production of missing transverse energy, additional jets and leptons (e, and ), and additional b quarks. We find no evidence for any anomalous production of ␥b or ␥bϩX events. We present limits on two supersymmetric models: a model where the photon is produced in the decay 2 0 →␥ 1 0 , and a model where the photon is produced in the neutralino decay into the gravitino LSP, 1 0 →␥G . We also present our limits in a modelindependent form and test methods of applying model-independent limits.
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