244 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
Search for New Particles Decaying to Dijets at CDF
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.Comment: 18 pages, 4 figures, 1 table. Submitted to Physical Review D Rapid
Communications. Postscript file of paper is also available at
http://www-cdf.fnal.gov/physics/pub97/cdf3276_dijet_search_prd_rc.p
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
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
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
Further Properties of High-Mass Multijet Events at the Fermilab Proton-Antiproton Collider
The properties of high-mass multijet events produced at the Fermilab
proton-antiproton collider are compared with leading order QCD matrix element
predictions, QCD parton shower Monte Carlo predictions, and the predictions
from a model in which events are distributed uniformly over the available
multibody phase-space. Multijet distributions corresponding to (4N-4) variables
that span the N-body parameter space are found to be well described by the QCD
calculations for inclusive three-jet, four-jet, and five-jet events. The
agreement between data, QCD Matrix Element calculations, and QCD parton shower
Monte Carlo predictions suggests that 2 -> 2 scattering plus gluon radiation
provides a good first approximation to the full LO QCD matrix element for
events with three, four, or even five jets in the final state.Comment: 49 pages with 19 figures. Submitted to Phys. Rev. D. PostScript with
full resolution figures also available at
http://www-cdf.fnal.gov/physics/pub96/cdf3480_multijet_prd_draft3.p
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
Search For Charged Higgs Decays of the Top Quark Using Hadronic Decays of the Tau Lepton
This Letter describes a direct search for charged Higgs boson production in
proton-antiproton collisions at sqrt(s)=1.8 TeV recorded by the Collider
Detector at Fermilab. Two-Higgs-doublet extensions to the standard model
predict the existence of charged Higgs bosons. In such models, the branching
fraction for top quarks B(t --> H b --> tau nu b) can be large. This search
uses the hadronic decays of the tau lepton in this channel to significantly
extend previous limits on charged Higgs production.Comment: 6pages, 4 figures, 1 table; LaTeX; submitted to PR
Study of ttbar Production in ppbar Collisions Using Total Transverse Energy
We analyze a sample of W + jet events collected with the Collider Detector at
Fermilab (CDF) in ppbar collisions at sqrt(s) = 1.8 TeV to study ttbar
production. We employ a simple kinematical variable "H", defined as the scalar
sum of the transverse energies of the lepton, neutrino and jets. For events
with a W boson and four or more jets, the shape of the "H" distribution
deviates by 3.8 standard deviations from that expected from known backgrounds
to ttbar production. However this distribution agrees well with a linear
combination of background and ttbar events, the agreement being best for a top
mass of 180 GeV/c^2.Comment: Postscript file (gzip+uuencode). 5-page, two-column PRL format
(RevTex). Submitted to Phys. Rev. Lett. 09 June 199
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