286 research outputs found
Search for charged Higgs decays of the top quark using hadronic tau decays
We present the result of a search for charged Higgs decays of the top quark,
produced in collisions at 1.8 TeV. When the charged
Higgs is heavy and decays to a tau lepton, which subsequently decays
hadronically, the resulting events have a unique signature: large missing
transverse energy and the low-charged-multiplicity tau. Data collected in the
period 1992-1993 at the Collider Detector at Fermilab, corresponding to
18.70.7~pb, exclude new regions of combined top quark and charged
Higgs mass, in extensions to the standard model with two Higgs doublets.Comment: uuencoded, gzipped tar file of LaTeX and 6 Postscript figures; 11 pp;
submitted to Phys. Rev.
Inclusive jet cross section in collisions at TeV
The inclusive jet differential cross section has been measured for jet
transverse energies, , from 15 to 440 GeV, in the pseudorapidity region
0.10.7. The results are based on 19.5 pb 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 GeV is significantly
higher than current predictions based on O() perturbative QCD
calculations. Various possible explanations for the high- excess are
discussed.Comment: 8 pages with 2 eps uu-encoded figures Submitted to Physical Review
Letter
Measurement of Dijet Angular Distributions at CDF
We have used 106 pb^-1 of data collected in proton-antiproton collisions at
sqrt(s)=1.8 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 (NLO) predictions of Quantum
Chromodynamics (QCD) in all dijet invariant mass regions. The data exclude at
95% confidence level (CL) a model of quark substructure in which only up and
down quarks are composite and the contact interaction scale is Lambda_ud(+) <
1.6 TeV or Lambda_ud(-) < 1.4 TeV. For a model in which all quarks are
composite the excluded regions are Lambda(+) < 1.8 TeV and Lambda(-) < 1. 6
TeV.Comment: 16 pages, 2 figures, 2 tables, LaTex, using epsf.sty. Submitted to
Physical Review Letters on September 17, 1996. Postscript file of full paper
available at http://www-cdf.fnal.gov/physics/pub96/cdf3773_dijet_angle_prl.p
Observation of charmless hadronic B decays
Four candidates for charmless hadronic B decay are observed in a data sample of four million hadronic Z decays recorded by the ALEPH detector at LEP. The probability that these events come from background sources is estimated to be less than 10(-6). The average branching of weakly decaying B hadrons (a mixture of B-d(0), B-s(0) and Lambda(b) weighted by their production The average branching ratio of weakly decaying B hadrons (a mixture of B-d(0) cross sections and lifetimes, here denoted B) into two long-lived charged hadrons (pions, kaons or protons) is measured to be Br(B-->h(+)h(-))=(1.7(-0.7)(+1.0)+/-0.2)x10(-5). The relative branching fraction Br(B-d(s)(0)-->pi(+)pi(-)(K-))/Br(B-d(s)(0)-->h(+)h(-)) is measured to be 1.0(-0.3-0.1)(+0.0+0.0). In addition, branching ratio upper limits are obtained for a variety of exclusive charmless hadronic two-body decays of B hadrons
Four-fermion production in collisions at centre-of-mass energies of 130 and 136 GeV
Four-fermion events have been selected in a data sample of 5.8 pb−1 collected with the aleph detector at centre-of-mass energies of 130 and 136 GeV. The final states , ℓ+ℓ−ℓ+ℓ−, , and have been examined. Five events are observed in the data, in agreement with the Standard Model predictions of 6.67±0.38 events from four-fermion processes and 0.14−0.05+0.19 from background processes
Search for New Particles Decaying to Dijets in p-pbar Collisions at sqrt(s)=1.8 TeV
We have used 19 pb**-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, excited quarks with mass between 80 and 570 GeV,
and color octet technirhos with mass between 320 and 480 GeV.Comment: Submitted to Physical Review Letters in December 199
Measurement of and in collisions at TeV
We present a measurement of and in proton - antiproton collisions at TeV
using a significantly improved understanding of the integrated luminosity. The
data represent an integrated luminosity of 19.7 pb from the 1992-1993
run with the Collider Detector at Fermilab (CDF). We find ~nb and ~nb.Comment: Uses Latex, Article 12 point, figure appended as uuencoded file The
full PostScript available via WWW at
http://www-cdf.fnal.gov/physics/pub95/cdf3312_sigma_1a_prl_v3.p
Ratios of bottom meson branching fractions involving J/psi mesons and determination of b quark fragmentation fractions
We report a measurement of the ratios of the decay rates of the B^+, B^0 and
B^0_s mesons into exclusive final states containing a J/psi meson. The final
states were selected from 19.6 pb^{-1} of p-pbar collisions recorded by the
Collider Detector at Fermilab. These data are interpreted to determine the
bquark fragmentation fractions f_u, f_d and f_s. We also determine the
branching fractions for the decay modes B^+ --> J/psi K^+, B^+ --> J/psi
K^*(892)^+, B^0 --> J/psi K^0, B^0 --> J/psi K^*(892)^0 and B_s^0 --> J/psi
phi(1020). We discuss the implications of these measurements to B meson decay
models.Comment: 40 pages with 5 figures. Submitted to Phys. Rev. D. PostScript also
available at http://www-cdf.fnal.gov/physics/pub96/cdf3609_bfrag_br_prd.p
Search for Higgs Bosons Decaying into b anti-b and Produced in Association with a Vector Boson in Proton-Antiproton Collisions at 1.8 TeV
We present a new search for production, where is a scalar
Higgs boson decaying into with branching ratio , and is a
boson decaying into , , or .
This search is then combined with previous searches for where is a
boson or a hadronically decaying . The data sample consists of
pb of collisions at TeV
accumulated by the Collider Detector at Fermilab. Observing no evidence of a
signal, we set 95% Bayesian credibility level upper limits on
. For masses of 90, 110 and 130
GeV/, the limits are 7.8, 7.2, and 6.6 pb respectively.Comment: 6 pages, 3 figures, to be submiited to PR
Measurement of dsigma/DM Forward-Backward Charge Asymmetry for High Mass Drell-Yan e+e- Pairs from p-pbar Collisions at sqrt(s)=1.8 TeV
We report on a measurement of the mass dependence of the forward-backward
charge asymmetry, A_FB, and production cross section dsigma/dM for e+e- pairs
with mass M_ee>40 GeV/c2. The data sample consists of 108 pb-1 of p-pbar
collisions at sqrt(s)=1.8 TeV taken by the Collider Detector at Fermilab during
1992-1995. The measured asymmetry and dsigma/dM are compared with the
predictions of the Standard Model and a model with an extra Z' gauge boson.Comment: 7 pages submitted to Phys. Rev. Lett. 1 figure, 2 Table
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