113 research outputs found
Measurement of and Production in Collisions at = 1.96 TeV
The Standard Model predictions for and production are
tested using an integrated luminosity of 200 pb of \ppbar collision data
collected at the Collider Detector at Fermilab. The cross sections are measured
selecting leptonic decays of the and bosons, and photons with
transverse energy GeV that are well separated from leptons. The
production cross sections and kinematic distributions for the and
are compared to SM predictions.Comment: 7 pages, 4 figures, submitted to PR
Observation of Bs-Bsbar Oscillations
We report the observation of Bs-Bsbar oscillations from a time-dependent
measurement of the Bs-Bsbar oscillation frequency Delta ms. Using a data sample
of 1 fb^-1 of p-pbar collisions at sqrt{s}=1.96 TeV collected with the CDF II
detector at the Fermilab Tevatron, we find signals of 5600 fully reconstructed
hadronic Bs decays, 3100 partially reconstructed hadronic Bs decays, and 61500
partially reconstructed semileptonic Bs decays. We measure the probability as a
function of proper decay time that the Bs decays with the same, or opposite,
flavor as the flavor at production, and we find a signal for Bs-Bsbar
oscillations. The probability that random fluctuations could produce a
comparable signal is 8 X 10^-8, which exceeds 5 sigma significance. We measure
Delta ms = 17.77 +- 0.10 (stat) +- 0.07 (syst) ps^-1
and extract
|Vtd/Vts| = 0.2060 +- 0.0007 (exp) + 0.0081 - 0.0060 (theor).Comment: 9 pages, 5 figures, submitted to Physical Review Letter
Double Diffraction Dissociation at the Fermilab Tevatron Collider
We present results from a measurement of double diffraction dissociation in
collisions at the Fermilab Tevatron collider. The production cross
section for events with a central pseudorapidity gap of width
(overlapping ) is found to be [] at [630]
GeV. Our results are compared with previous measurements and with predictions
based on Regge theory and factorization.Comment: 10 pages, 4 figures, using RevTeX. Submitted to Physical Review
Letter
Measurement of the Ratio of Branching Fractions B(D0 -> K+ pi-)/B(D0 -> K- pi+) using the CDF II Detector
We present a measurement of R_B, the ratio of the branching fraction for the
rare decay D0 -> K+ pi- to that for the Cabibbo-favored decay D0 -> K- pi+.
Charge conjugate decays are implicitly included. A signal of 2005 +/- 104
events for the decay D0 -> K+ pi- is obtained using the CDF II detector at the
Fermilab Tevatron collider. The data set corresponds to an integrated
luminosity of 0.35 1/fb produced in p-bar/p collisions at sqrt{s}=1.96 TeV.
Assuming no mixing, we find R_B = [ 4.05 +/- 0.21 (stat) +/- 0.11 (syst) ] x
10(-3). This measurement is consistent with the world average, and comparable
in accuracy with the best measurements from other experiments.Comment: 7 pages, 3 figure
Measurement of the Meson Differential Cross Section, , in Collisions at TeV
This paper presents the first direct measurement of the meson
differential cross section, , in collisions at
TeV using a sample of pb accumulated by
the Collider Detector at Fermilab (CDF). The cross section is measured in the
central rapidity region GeV/ by fully
reconstructing the meson decays and , where and .
A comparison is made to the theoretical QCD prediction calculated at
next-to-leading order.Comment: 14 pages. Submitted to Phys. Rev. Lett. The postscript file is at
http://www-cdf.fnal.gov/physics/pub95/cdf2893_bexcl_xsection.p
Limits on and couplings from and production in collisions at TeV
Direct limits are set on and three-boson couplings in a
search for and production with high transverse momentum in
collisions at TeV, using the Collider Detector
at Fermilab. The results are in agreement with the SU(2) U(1) model of
electroweak interactions. Assuming Standard Model coupling, the the
limits are interpreted as direct evidence for a non-zero coupling at
subprocess energies near 500 GeV. Alternatively, assumiong identical and
couplings, bounds and are obtained at CL for a form factor scale 1000 GeV.Comment: 16 pages, submitted to PRL, URL:
http://www-cdf.fnal.gov/physics/pub95/cdf2951_vvprl.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
Measurement of the Top Quark Mass with the Collider Detector at Fermilab
This report describes a measurement of the top quark mass in \ppbar
collisions at a center of mass energy of 1.8 TeV. The data sample was collected
with the CDF detector during the 1992--95 collider run at the Fermilab
Tevatron, and corresponds to an integrated luminosity of 106 \pb. Candidate
events in the ``lepton+jets'' decay channel provide our most precise
measurement of the top quark mass. For each event a top mass is determined by
using energy and momentum constraints on the production of the \ttbar pair
and its subsequent decay. A likelihood fit to the distribution of reconstructed
masses in the data sample gives a top mass in the lepton+jets channel of
176.1\pm 5.1 (stat.)\pm 5.3 (syst.) \gevcc. Combining this result with
measurements from the ``all-hadronic'' and ``dilepton'' decay topologies yields
a top mass of 176.1\pm 6.6 \gevcc.Comment: 158 pages, 41 figure
Observation of B-s(0)-\u3e K+K- and measurements of branching fractions of charmless two-body decays of B-0 and B-s(0) mesons in pp collisions at root s=1.96 TeV
We search for decays of the type B-(s)(0)-\u3e h(+)h(\u27-) (where h,h(\u27)=K or pi) in 180 pb(-1) of (p) over barp collisions collected at the Tevatron by the upgraded Collider Detector at Fermilab. We report the first observation of the new mode B-s(0)-\u3e K+K- with a yield of 236 +/- 32 events, corresponding to (f(s)/f(d))xB(B-s(0)-\u3e K+K-)/B(B-0 -\u3e K+pi(-))=0.46 +/- 0.08(stat)+/- 0.07(syst), where f(s)/f(d) is the ratio of production fractions of B-s(0) and B-0. We find results in agreement with world averages for the B-0 modes, and set the following new limits at 90% C.L.: B(B-s(0)-\u3e K-pi(+))\u3c 5.6x10(-6) and B(B-s(0)-\u3epi(+)pi(-))\u3c 1.7x10(-6)
Measurement of the D+->pi(+) pi(0) and D+-> K+ pi(0) branching fractions
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