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CDF Collaboration

Publications and source records attributed to CDF Collaboration.

At least 73 records · Page 4Linked to original sources

arXiv2013

Measurement of the leptonic asymmetry in ttbar events produced in ppbar collisions at sqrt(s)=1.96 TeV

We measure the asymmetry in the charge-weighted rapidity of the lepton in semileptonic ttbar decays recorded with the CDF II detector using the full Tevatron Run II sample, corresponding to an integrated luminosity of 9.4/fb. A parametrization of the asymmetry as a function of the charge-weighted rapidity is used to correct for the finite acceptance of the detector and recover the production-level asymmetry. The result of afb(lep) = 0.094 +0.032 -0.029 is to be compared to the standard model next-to-leading-order prediction of afb(lep) = 0.038 +-0.003.

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arXiv2013

Combination of CDF and D0 W-Boson Mass Measurements

We summarize and combine direct measurements of the mass of the $W$ boson in $\sqrt{s} = 1.96 \text{TeV}$ proton-antiproton collision data collected by CDF and D0 experiments at the Fermilab Tevatron Collider. Earlier measurements from CDF and D0 are combined with the two latest, more precise measurements: a CDF measurement in the electron and muon channels using data corresponding to $2.2 \mathrm{fb}^{-1}$ of integrated luminosity, and a D0 measurement in the electron channel using data corresponding to $4.3 \mathrm{fb}^{-1}$ of integrated luminosity. The resulting Tevatron average for the mass of the $W$ boson is $\MW = 80\,387 \pm 16 \text{MeV}$. Including measurements obtained in electron-positron collisions at LEP yields the most precise value of $\MW = 80\,385 \pm 15 \text{MeV}$.

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arXiv2013

Measurement of the cross section for direct-photon production in association with a heavy quark in $p\bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV

We report on a measurement of the cross section for direct-photon production in association with a heavy quark using the full data set of $\sqrt{s}=1.96$ TeV proton-antiproton collisions corresponding to 9.1 fb$^{-1}$ of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron. The measurements are performed as a function of the photon transverse momentum, covering photon transverse momentum between 30 and 300 GeV, photon rapidities $|y^γ|<1.0$, heavy-quark-jet transverse momentum $p_{T}^{jet}>20$ GeV, and jet rapidities $|y^{jet}|<1.5$. The results are compared with several theoretical predictions.

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arXiv2013

A signature-based search for delayed photons in exclusive photon plus missing transverse energy events from $p \bar{p}$ collisions with $\sqrt{s} = 1.96$ TeV

We present the first signature-based search for delayed photons using an exclusive photon plus missing transverse energy final state. Events are reconstructed in a data sample from the CDF II detector corresponding to $6.3 \text{fb}^{-1}$ of integrated luminosity from $\sqrt{s}=1.96$ TeV proton-antiproton collisions. Candidate events are selected if they contain a photon with an arrival time in the detector larger than expected from a promptly-produced photon. The mean number of events from standard model sources predicted by the data-driven background model based on the photon timing distribution is $286 \pm 24$. A total of 322 events are observed. A $p$-value of 12% is obtained, showing consistency of the data with standard model predictions.

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arXiv2013

Searches for the Higgs boson decaying to W^{+} W^{-} -> l^{+}nu l^{-}nubar with the CDF II detector

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 $p\bar{p}$ 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/$c^2$.

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arXiv2013

Top-quark mass measurement in events with jets and missing transverse energy using the full CDF data set

We present a measurement of the top-quark mass using the full data set of Tevatron $\sqrt{s} = 1.96$ TeV proton-antiproton collisions recorded by the CDF II detector, corresponding to an integrated luminosity of \invfb{8.7}. The analysis uses events with one semileptonic $t$ or $\bar{t}$ decay, but without detection of the electron or muon. We select events with significant missing transverse energy and multiple jets. We veto events containing identified electrons or muons. We obtain distributions of the top-quark masses and the invariant mass of the two jets from $W$-boson decays from data and compare these to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with {\it in situ} calibration. A likelihood fit of the templates from signal and background events to the data yields the top-quark mass, $\mtop = \gevcc{\measStatSyst{173.93}{1.64}{0.87}}$. This result is the most precise measurement to date of the mass of the top quark in this event topology.

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arXiv2013

Search for Supersymmetry with Like-Sign Lepton-Tau Events at CDF

We present a search for chargino-neutralino associated production using like electric charge dilepton events collected by the CDF II detector at the Fermilab Tevatron in proton-antiproton collisions at $\sqrt{s} = 1.96$ TeV. One lepton is identified as the hadronic decay of a tau lepton, while the other is an electron or muon. In data corresponding to 6.0 fb$^{-1}$ of integrated luminosity, we obtain good agreement with standard model predictions, and set limits on the chargino-neutralino production cross section for simplified gravity- and gauge-mediated models. As an example, assuming that the chargino and neutralino decays to taus dominate, in the simplified gauge-mediated model we exclude cross sections greater than 300 fb at 95% credibility level for chargino and neutralino masses of 225 \gevcc. This analysis is the first to extend the LHC searches for electroweak supersymmetric production of gauginos to high $\tanβ$ and slepton next-to-lightest supersymmetric particle scenarios.

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arXiv2013

Combination of searches for the Higgs boson using the full CDF data set

We present a combination of searches for the standard model Higgs boson using the full CDF Run II data set, which corresponds to an integrated luminosity of 9.45--10.0 fb$^{-1}$ collected from $\sqrt{s}=1.96$ TeV $p{\bar{p}}$ collisions at the Fermilab Tevatron. The searches consider Higgs boson production from gluon-gluon fusion, vector-boson fusion, and associated production with either a $W$ or $Z$ boson or a $t{\bar{t}}$ pair. Depending on the production mode, Higgs boson decays to $W^+W^-$, $ZZ$, $b{\bar{b}}$, $τ^+τ^-$, and $γγ$ are examined. We search for a Higgs boson with masses ($m_H$) in the range 90--200 GeV/$c^2$. In the absence of a signal, we expect based on combined search sensitivity to exclude at the 95% credibility level the mass regions $90<m_H<94$ GeV/$c^2$, $96<m_H<106$ GeV/$c^2$, and $153<m_H<175$ GeV/$c^2$. The observed exclusion regions are $90<m_H<102$ GeV/$c^2$ and $149<m_H<172$ GeV/$c^2$. A moderate excess of signal-like events relative to the background expectation at the level of 2.0 standard deviations is present in the data for the $m_H=125$ GeV/$c^2$ search hypothesis. We also present interpretations of the data within the context of a fermiophobic model and an alternative standard model incorporating a fourth generation of fermions. Finally, for the hypothesis of a new particle with mass 125 GeV/$c^2$, we constrain the coupling strengths of the new particle to $W^\pm$ bosons, $Z$ bosons, and fermions.

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arXiv2013

Measurement of the top quark forward-backward production asymmetry and its dependence on event kinematic properties

We present new measurements of the inclusive forward-backward ttbar production asymmetry, AFB, and its dependence on several properties of the ttbar system. The measurements are performed with the full Tevatron data set recorded with the CDF II detector during ppbar collisions at sqrt(s) = 1.96 TeV, corresponding to an integrated luminosity of 9.4 fb^(-1). We measure the asymmetry using the rapidity difference Delta-y=y_(t)-y_(tbar). Parton-level results are derived, yielding an inclusive asymmetry of 0.164+/-0.047 (stat + syst). We observe a linear dependence of AFB on the top-quark pair mass M(ttbar) and the rapidity difference |Delta-y| at detector and parton levels. Assuming the standard model, the probabilities to observe the measured values or larger for the detector-level dependencies are 7.4*10^(-3) and 2.2*10^(-3) for M(ttbar) and |Delta-y| respectively. Lastly, we study the dependence of the asymmetry on the transverse momentum of the ttbar system at the detector level. These results are consistent with previous lower-precision measurements and provide additional quantification of the functional dependencies of the asymmetry.

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arXiv2013

Measurement of R = \boldmath${\mathcal{B}(t \rightarrow Wb)/\mathcal{B}(t \rightarrow Wq)} $ in Top--quark--pair Decays using Lepton+jets Events and the Full CDF Run II Data set

We present a measurement of the ratio of the top-quark branching fractions $R=\mathcal{B}(t\rightarrow Wb)/\mathcal{B}(t\rightarrow Wq)$, where $q$ represents quarks of type $b$, $s$, or $d$, in the final state with a lepton and hadronic jets. The measurement uses $\sqrt{s}$ = 1.96 TeV proton--antiproton collision data from 8.7 fb$^{-1}$ of integrated luminosity collected with the Collider Detector at Fermilab during Run II of the Tevatron. We simultaneously measure $R=0.94 \pm 0.09$ (stat+syst), the $t\bar{t}$ production cross section $σ_{t \bar t} = 7.5 \pm 1.0$ (stat+syst) pb. The magnitude of the Cabibbo-Kobayashi-Maskawa matrix element, $|V_{tb}| = 0.97 \pm 0.05$ (stat+syst) is extracted assuming three generations of quarks, and a lower limit of $|V_{tb}|>0.89$ at 95% credibility level is set.

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arXiv2013

Measurement of the cross section for prompt isolated diphoton production using the full CDF Run II data sample

This Letter reports a measurement of the cross section for producing pairs of central prompt isolated photons in proton-antiproton collisions at a total energy of 1.96 TeV using data corresponding to 9.5/fb integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. The measured differential cross section is compared to three calculations derived from the theory of strong interactions. These include a prediction based on a leading order matrix element calculation merged with parton shower, a next-to-leading order, and a next-to-next-to-leading order calculation. The first and last calculations reproduce most aspects of the data, thus showing the importance of higher-order contributions for understanding the theory of strong interaction and improving measurements of the Higgs boson and searches for new phenomena in diphoton final states.

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arXiv2013

Search for $B_s \rightarrow μ^{+}μ^{-}$ and $B_d \rightarrow μ^{+}μ^{-}$ decays with the full CDF Run II data set

We report on a search for \bsmm\ and \bdmm\ decays using proton-antiproton collision data at $\sqrt{s}=1.96$ TeV corresponding to $10 \fb$ of integrated luminosity collected by the CDF detector at the Fermilab Tevatron collider. The observed number of \bd\ candidates is consistent with background-only expectations and yields an upper limit on the branching fraction of $\brbdmm < 4.6\times 10^{-9}$ at 95% confidence level. We observe an excess of \bs\ candidates. The probability that the background processes alone could produce such an excess or larger is 0.94%. The probability that the combination of background and the expected standard model rate of \bsmm\ could produce such an excess or larger is 6.8%. These data are used to determine a branching fraction $\brbsmm = (1.3^{+0.9}_{-0.7}) \times 10^{-8} $ and provide an upper limit of $\brbsmm < 3.1\times 10^{-8}$ at 95% confidence level.

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arXiv2013

Search for pair-production of strongly-interacting particles decaying to pairs of jets in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV

We present a search for the pair-production of a non-standard-model strongly-interacting particle that decays to a pair of quarks or gluons, leading to a final state with four hadronic jets. We consider both non-resonant production via an intermediate gluon as well as resonant production via a distinct non-standard-model intermediate strongly-interacting particle. We use data collected by the CDF experiment in proton-antiproton collisions at $\sqrt{s}=1.96$ TeV corresponding to an integrated luminosity of 6.6 fb$^{-1}$. We find the data to be consistent with standard model predictions. We report limits on $σ(p\bar{p}\rightarrow$ {\it jjjj}$)$ as a function of the masses of the hypothetical intermediate particles. Upper limits on the production cross sections for non-standard-model particles in several resonant and non-resonant processes are also derived.

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arXiv2013

Observation of the Production of a W Boson in Association with a Single Charm Quark

The first observation of the production of a $W$ boson with a single charm quark ($c$) jet in $p\bar{p}$ collisions at $\sqrt{s}=1.96 {\rm TeV}$ is reported. The analysis uses data corresponding to 4.3 fb$^{-1}$, recorded with the CDF II detector at the Fermilab Tevatron. Charm quark candidates are selected through the identification of an electron or muon from charm-hadron semileptonic decay within a hadronic jet, and a $Wc$ signal is observed with a significance of 5.7 standard deviations. The production cross section $σ_{Wc}(p_{Tc}>20 {\rm GeV}/c, |η_c|<1.5)\times B(W\rightarrow \ellν)$ is measured to be $13.6^{+3.4}_{-3.1} {\rm pb}$ and is in agreement with theoretical expectations. From this result the magnitude of the quark-mixing matrix element $V_{cs}$ is derived, $|V_{cs}|=1.08\pm0.16$ along with a lower limit of $|V_{cs}|>0.71$ at the 95% confidence level, assuming that the $Wc$ production through $c$ to $s$ quark coupling is dominant.

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arXiv2013

Measurement of W-Boson Polarization in Top-quark Decay using the Full CDF Run II Data Set

We measure the polarization of W bosons from top-quark (t) decays into final states with a charged lepton and jets, tt --> WbWb --> lvbqqb, using the full Run II data set collected by the CDF II detector. A model-independent method simultaneously determines the fraction of longitudinal (f_0) and right-handed (f_+) W bosons to yield f_0 = 0.726 +/- 0.066 (stat) +/- 0.067 (syst) and f_+ = -0.045 +/- 0.044 (stat) +/- 0.058 (syst) with a correlation coefficient of -0.69. Additional results are presented under various standard model assumptions. No significant discrepencies with the standard model are observed.

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arXiv2013

Updated search for the standard model Higgs boson in events with jets and missing transverse energy using the full CDF data set

We present an updated search for the Higgs boson produced in association with a vector boson in the final state with missing transverse energy and two jets. We use the full CDF data set corresponding to an integrated luminosity of 9.45 fb${}^{-1}$ at a proton-antiproton center-of-mass energy of $\sqrt{s}=1.96$ TeV. New to this analysis is the inclusion of a $b$-jet identification algorithm specifically optimized for $H\to b\bar{b}$ searches. Across the Higgs boson mass range $90 \le m_H \le 150$ GeV$/c^2$, the expected 95% credibility level upper limits on the $V H$ production cross section times the $H\to b\bar{b}$ branching fraction are improved by an average of 14% relative to the previous analysis. At a Higgs boson mass of 125 GeV$/c^2$, the observed (expected) limit is 3.06 (3.33) times the standard model prediction, corresponding to one of the most sensitive searches to date in this final state.

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arXiv2013

Measurement of the $B_c^{-}$ meson lifetime in the decay $B_{c}^{-} \rightarrow J/ψ~π^{-}$

The lifetime of the $B_c^{-}$ meson is measured using 272 exclusive $B_{c}^{-} \to J/ψ(\to μ^+μ^-) π^-$ decays reconstructed in data from proton-antiproton collisions corresponding to an integrated luminosity of 6.7 fb$^{-1}$ recorded by the CDF II detector at the Fermilab Tevatron. The lifetime of the $B_c^{-}$ meson is measured to be $τ$($B_c^{-}$) = 0.452 $\pm$ 0.048(stat) $\pm$ 0.027(syst) ps. This is the first measurement of the $B_c^{-}$ meson lifetime in a fully-reconstructed hadronic channel, and it agrees with previous results and has comparable precision.

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arXiv2012

Search for a two-Higgs-boson doublet using a simplified model in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV

We present a search for new particles in an extension to the standard model that includes a heavy Higgs boson ($H^0$), a lighter charged Higgs boson ($H^\pm$), and an even-lighter Higgs boson $h^0$, with decays leading to a $W$-boson pair and a bottom-antibottom quark pair in the final state. We use events with exactly one lepton, missing transverse momentum, and at least four jets in data corresponding to an integrated luminosity of 8.7 fb$^{-1}$ collected by the CDF II detector in proton-antiproton collisions at $\sqrt{s}=1.96$ TeV. We find the data to be consistent with standard model predictions and report the results in terms of a simplified Higgs-cascade-decay model, setting 95% confidence level upper limits on the product of cross-section and branching fraction from 1.3 pb to 15 fb as a function of $H^0$ and $H^\pm$ masses for $m_h^{0}=126$ GeV$/c^2$.

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