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Register a new userNew Results on Bottom Baryons with the CDF II Detector
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We present measurements of the masses and widths of four bottom baryon resonances, Sigma_b(*)+-, reconstructed in the Lambda_b pi+- hadron decay modes. The isospin mass splittings for the Sigma_b and Sigma_b* multiplets are extracted as well. The analysis is based on a data sample corresponding to an integrated luminosity of 6 fb^-1 .
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In this paper we review a selection of recent results obtained, in the area of QCD physics, from the CDF-II experiment that studies $pbar{p}$ collisions at $sqrt{s}$=1.96 TeV provided by the Fermilab Tevatron Collider. All results shown correspond to analysis performed using the Tevatron Run II data samples. In particular we will illustrate the progress achieved and the status of our studies on the following QCD processes: jet inclusive production, using different jet clustering algorithm, $W(to e u_e)+ $jets and $Z(to e^+ e^-)+ $jets production, $gamma+b-$jet production, dijet production in double pomeron exchange and finally exclusive $e^+e^-$ and $gamma gamma$ production. No deviations from the Standard Model have been observed so far.
We measure the time dependence of the ratio of decay rates for D0 -> K+ pi- to the Cabibbo-favored decay D0 -> K- pi+. The charge conjugate decays are included. A signal of 3.3 x 10^4 D*+ -> pi+ D0, D0 -> K+ pi- decays is obtained with D0 proper decay times between 0.75 and 10 mean D0 lifetimes. The data were recorded with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 9.6 fb-1 for p-pbar collisions at sqrt(s) = 1.96 TeV. Assuming CP conservation, we search for D0-D0bar mixing and measure the mixing parameters to be R_D = (3.51 +/- 0.35) x 10^{-3}, y = (4.3 +/- 4.3) x 10^{-3}, and x^2 = (0.08 +/- 0.18) x 10^{-3}. We report Bayesian probability intervals in the x^2 - y plane and find that the significance of excluding the no-mixing hypothesis is equivalent to 6.1 Gaussian standard deviations, providing the second observation of D0-D0bar mixing from a single experiment.
We report on a search for charged massive resonances decaying to top ($t$) and bottom ($b$) quarks in the full data set of proton-antiproton collisions at center-of-mass energy of $sqrt{s} = 1.96$ TeV collected by the CDF~II detector at the Tevatron, corresponding to an integrated luminosity of 9.5 $fb^{-1}$. No significant excess above the standard model (SM) background prediction is observed. We set 95% Bayesian credibility mass-dependent upper limits on the heavy charged particle production cross section times branching ratio to $t b$. Using a SM extension with a $W^{prime}$ and left-right-symmetric couplings as a benchmark model, we constrain the $W^{prime}$ mass and couplings in the 300 to 900 GeV/$c^2$ range. The limits presented here are the most stringent for a charged resonance with mass in the range 300 -- 600 GeV/$c^2$ decaying to top and bottom quarks.
We present a search for a standard model Higgs boson decaying to two $W$ bosons that decay to leptons using the full data set collected with the CDF II detector in $sqrt{s}=1.96$ TeV $pbar{p}$ collisions at the Fermilab Tevatron, corresponding to an integrated luminosity of 9.7 fb${}^{-1}$. We obtain no evidence for production of a standard model Higgs boson with mass between 110 and 200 GeV/$c^2$, and place upper limits on the production cross section within this range. We exclude standard model Higgs boson production at the 95% confidence level in the mass range between 149 and 172 GeV/$c^2$, while expecting to exclude, in the absence of signal, the range between 155 and 175 GeV/$c^2$. We also interpret the search in terms of standard model Higgs boson production in the presence of a fourth generation of fermions and within the context of a fermiophobic Higgs boson model. For the specific case of a standard model-like Higgs boson in the presence of fourth-generation fermions, we exclude at the 95% confidence level Higgs boson production in the mass range between 124 and 200 GeV/$c^2$, while expecting to exclude, in the absence of signal, the range between 124 and 221 GeV/$c^2$.
We present a measurement of the CP-violating parameter betas using approximately 6500 $BsJpsiPhi$ decays reconstructed with the CDF,II detector in a sample of $pbar p$ collisions at $sqrt{s}=1.96$ TeV corresponding to 5.2 fb$^{-1}$ integrated luminosity produced by the Tevatron Collider at Fermilab. We find the CP-violating phase to be within the range $betas in [0.02, 0.52] cup [1.08, 1.55]$ at 68% confidence level where the coverage property of the quoted interval is guaranteed using a frequentist statistical analysis. This result is in agreement with the standard model expectation at the level of about one Gaussian standard deviation. We consider the inclusion of a potential $S$-wave contribution to the $Bsto J/psi K^+K^-$ final state which is found to be negligible over the mass interval $1.009 < m(K^+K^-)<1.028 gevcc$. Assuming the standard model prediction for the CP-violating phase betas, we find the Bs decay width difference to be $deltaG = 0.075 pm 0.035,textrm{(stat)} pm 0.006,textrm{(syst)} ps$. We also present the most precise measurements of the Bs mean lifetime $tau(Bs) = 1.529 pm 0.025,textrm{(stat)} pm 0.012,textrm{(syst)}$ ps, the polarization fractions $|A_0(0)|^2 = 0.524 pm 0.013,textrm{(stat)} pm 0.015,textrm{(syst)}$ and $|A_{parallel}(0)|^2 = 0.231 pm 0.014,textrm{(stat)} pm 0.015,textrm{(syst)}$, as well as the strong phase $delta_{perp}= 2.95 pm 0.64,textrm{(stat)} pm 0.07,textrm{(syst)} textrm{rad}$. In addition, we report an alternative Bayesian analysis that gives results consistent with the frequentist approach.
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