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The CDF Collaboration

Publications and source records attributed to The CDF Collaboration.

At least 73 records · Page 4Linked to original sources

arXiv2009

Measurement of the top quark mass at CDF using the "neutrino $ϕ$ weighting" template method on a lepton plus isolated track sample

We present a measurement of the top quark mass with t-tbar dilepton events produced in p-pbar collisions at the Fermilab Tevatron $\sqrt{s}$=1.96 TeV and collected by the CDF II detector. A sample of 328 events with a charged electron or muon and an isolated track, corresponding to an integrated luminosity of 2.9 fb$^{-1}$, are selected as t-tbar candidates. To account for the unconstrained event kinematics, we scan over the phase space of the azimuthal angles ($ϕ_{ν_1},ϕ_{ν_2}$) of neutrinos and reconstruct the top quark mass for each $ϕ_{ν_1},ϕ_{ν_2}$ pair by minimizing a $χ^2$ function in the t-tbar dilepton hypothesis. We assign $χ^2$-dependent weights to the solutions in order to build a preferred mass for each event. Preferred mass distributions (templates) are built from simulated t-tbar and background events, and parameterized in order to provide continuous probability density functions. A likelihood fit to the mass distribution in data as a weighted sum of signal and background probability density functions gives a top quark mass of $165.5^{+{3.4}}_{-{3.3}}$(stat.)$\pm 3.1$(syst.) GeV/$c^2$.

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arXiv2009

Search for WW and WZ production in lepton plus jets final state at CDF

We present a search for WW and WZ production in final states that contain a charged lepton (electron or muon) and at least two jets, produced in sqrt(s) = 1.96 TeV ppbar collisions at the Fermilab Tevatron, using data corresponding to 1.2 fb-1 of integrated luminosity collected with the CDF II detector. Diboson production in this decay channel has yet to be observed at hadron colliders due to the large single W plus jets background. An artificial neural network has been developed to increase signal sensitivity, as compared with an event selection based on conventional cuts. We set a 95% confidence level upper limit of sigma_{WW}* BR(W->lnu,W->jets)+ sigma_{WZ}*BR(W->lnu,Z->jets) <2.88 pb, which is consistent with the standard model next to leading order cross section calculation for this decay channel of 2.09+-0.12 pb.

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arXiv2009

Search for High-Mass \boldmath$e^+e^-$ Resonances in \boldmath$p\bar{p}$ Collisions at \boldmath$\sqrt{s}=$1.96 TeV

A search for high-mass resonances in the $e^+e^-$ final state is presented based on 2.5 fb$^{-1}$ of $\sqrt{s}=$1.96 TeV $p\bar{p}$ collision data from the CDF II detector at the Fermilab Tevatron. The largest excess over the standard model prediction is at an $e^+e^-$ invariant mass of 240 GeV/$c^2$. The probability of observing such an excess arising from fluctuations in the standard model anywhere in the mass range of 150--1,000 GeV/$c^2$ is 0.6% (equivalent to 2.5 $σ$). We exclude the standard model coupling $Z'$ and the Randall-Sundrum graviton for $k/\overline{M}_{Pl}=0.1$ with masses below 963 and 848 GeV/$c^2$ at the 95% credibility level, respectively.

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arXiv2009

Search for the Decays ${B^0_{(s)}\to e^+μ^-}$ and ${B^0_{(s)}\to e^+e^-}$ in CDF Run II

We report results from a search for the lepton flavor violating decays $B^0_{(s)}\to e^+μ^-$, and the flavor-changing neutral-current decays $B^0_{(s)} \to e^+ e^-$. The analysis uses data corresponding to ${\rm 2 fb^{-1}}$ of integrated luminosity of $p \bar{p}$ collisions at $\sqrt{s}=1.96 {\rm TeV}$ collected with the upgraded Collider Detector (CDF II) at the Fermilab Tevatron. The observed number of $B^0_{(s)}$ candidates is consistent with background expectations. The resulting Bayesian upper limits on the branching ratios at 90% credibility level are $\mathcal{B}(B^0_s \to e^{+}μ^{-}) < 2.0 \times 10^{-7}$, $\mathcal{B}(B^0 \to e^{+}μ^{-})< 6.4 \times 10^{-8}$, $\mathcal{B}(B^0_s \to e^{+}μ^{-}) < 2.0 \times 10^{-7}$ and $\mathcal{B}(B^0 \to e^{+}μ^{-})< 6.4 \times 10^{-8}$. From the limits on $\mathcal{B} (B^0_{(s)}\to e^+μ^-)$, the following lower bounds on the Pati-Salam leptoquark masses are also derived: ${M_{LQ}}(B^0_s\to e^+ μ^-) > 47.8 {\rm TeV/c^2}$, and ${M_{LQ}}(B^0\to e^+ μ^-) > 59.3 {\rm TeV/c^2}$, at 90% credibility level.

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arXiv2008

Search for new particles decaying into dijets in proton-antiproton collisions at sqrt(s) = 1.96 TeV

We present a search for new particles whose decays produce two jets (dijets) using proton-antiproton collision data corresponding to an integrated luminosity of 1.13 fb-1 collected with the CDF II detector. The measured dijet mass spectrum is found to be consistent with next-to-leading-order perturbative QCD predictions, and no significant evidence of new particles is found. We set upper limits at the 95% confidence level on cross sections times the branching fraction for the production of new particles decaying into dijets with both jets having a rapidity magnitude |y| < 1. These limits are used to determine the mass exclusions for the excited quark, axigluon, flavor-universal coloron, E6 diquark, color-octet technirho, W', and Z'.

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arXiv2008

Search for new physics in the mu+mu+e/mu+met channel with a low-pT lepton threshold at the Collider Detector at Fermilab

A search for new physics using three-lepton (trilepton) data collected with the CDF II detector and corresponding to an integrated luminosity of 976 pb-1 is presented. The standard model predicts a low rate of trilepton events, which makes some supersymmetric processes, such as chargino-neutralino production, measurable in this channel. The mu+mu+l signature is investigated, where l is an electron or a muon, with the additional requirement of large missing transverse energy. In this analysis, the lepton transverse momenta with respect to the beam direction (pT) are as low as 5 GeV/c, a selection that improves the sensitivity to particles which are light as well as to ones which result in leptonically decaying tau leptons. At the same time, this low-p_T selection presents additional challenges due to the non-negligible heavy-quark background at low lepton momenta. This background is measured with an innovative technique using experimental data. Several dimuon and trilepton control regions are investigated, and good agreement between experimental results and standard-model predictions is observed. In the signal region, we observe one three-muon event and expect 0.4+/-0.1 mu+mu+l events

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arXiv2008

Search for Maximal Flavor Violating Scalars in Same-Charge Lepton Pairs in $p\bar{p}$ Collisions at $\sqrt{s} = 1.96$ TeV

Models of Maximal Flavor Violation (MxFV) in elementary particle physics may contain at least one new scalar SU$(2)$ doublet field $Φ_{FV} = (η^0,η^+)$ that couples the first and third generation quarks ($q_1,q_3$) via a Lagrangian term $\mathcal{L}_{FV} = ξ_{13} Φ_{FV} q_1 q_3$. These models have a distinctive signature of same-charge top-quark pairs and evade flavor-changing limits from meson mixing measurements. Data corresponding to 2 fb$^{-1}$ collected by the CDF II detector in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV are analyzed for evidence of the MxFV signature. For a neutral scalar $η^0$ with $m_{η^0} = 200$ GeV/$c^2$ and coupling $ξ_{13}=1$, $\sim$ 11 signal events are expected over a background of $2.1 \pm 1.8$ events. Three events are observed in the data, consistent with background expectations, and limits are set on the coupling $ξ_{13}$ for $m_{η^0} = 180-300$ GeV/$c^2$.

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arXiv2007

Measurements of Inclusive W and Z Cross Sections in p-pbar Collisions at sqrt{s} =1.96 TeV

We report the first measurements of inclusive W and Z boson cross sections times the corresponding leptonic branching ratios for p pbar collisions at sqrt{s} = 1.96 TeV based on the decays of the W and Z bosons into electrons and muons. The data were recorded with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 72.0 +/- 4.3 pb-1. We test e-mu lepton universality in W decays by measuring the ratio of the W->mu nu to W->e nu cross sections and determine a value of 0.991 +/- 0.004(stat.) +/- 0.011(syst.) for the ratio of W-l-nu couplings (g_mu/g_e). Since there is no sign of non-universality, we combine our cross section measurements in the different lepton decay modes and obtain sigma*BR(W->lnu) = 2.749 +/- 0.010(stat.) +/- 0.053(syst.) +/- 0.165(lum.) nb and sigma*BR(gamma*/Z->ll)=254.9 +/- 3.3(stat.) +/- 4.6(syst.) +/- 15.2(lum.) pb for dilepton pairs in the mass range between 66 GeV/c^2 and 116 GeV/c^2. We compute the ratio R of the W->lnu to Z->ll cross sections taking all correlations among channels into account and obtain R=10.84 +/- 0.15(stat.) +/- 0.14(syst.) including a correction for the virtual photon exchange component in our measured gamma*/Z->ll cross section. Based on the measured value of R, we extract values for the W leptonic branching ratio, BR(W->lnu) =0.1082 +/- 0.0022; the total width of the W boson, Gamma(W) =2092 +/- 42 MeV; and the ratio of W and Z boson total widths, Gamma(W)/Gamma(Z) = 0.838 +/- 0.017. In addition, we use our extracted value of Gamma(W) whose value depends on various electroweak parameters and certain CKM matrix elements to constrain the V_CS CKM matrix element, |V_CS| = 0.976 +/- 0.030.

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arXiv2006

A search for top decay into tau, neutrino and quark in top-antitop production

We present a search for top-antitop events with a tau lepton in the final state. The data sample corresponds to an integrated luminosity of 194/pb collected with the CDF II detector from proton-antiproton collisions at a center of mass energy of 1.96 TeV. We observe two events with an expected signal of 1.0+/-0.2 events and a background of 1.3+/-0.3 events. We determine a 95% confidence level upper limit on r_tau, the ratio of the measured rate of top->tau nu quark to the expectation, of 5.2.

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arXiv2005

Measurement of the Inclusive Jet Cross Section using the Kt algorithm in pp-bar Collisions at sqrt(s) = 1.96 TeV

We report on a measurement of the inclusive jet production cross section in pp-bar collisions at sqrt{s} = 1.96 TeV using data collected with the upgraded Collider Detector at Fermilab in Run II (CDF II) corresponding to an integrated luminosity of 385 pb^-1. Jets are reconstructed using the kt algorithm. The measurement is carried out for jets with rapidity 0.1 < | yjet | < 0.7 and transverse momentum in the range 54 < ptjet < 700 GeV/c. The measured cross section is in good agreement with next-to-leading order perturbative QCD predictions after the necessary non-perturbative parton-to-hadron corrections are included.

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arXiv2005

Search for Bs -> mu+mu- and Bd -> mu+mu- Decays in ppbar Collisions with CDF II

We report on a search for Bs -> mu+mu- and Bd -> mu+mu- decays in ppbar collisions at sqrt(S) = 1.96 TeV using 364 pb-1 of data collected by the CDF II detector at the Fermilab Tevatron Collider. After applying all selection requirements, we observe no candidates inside the Bs or Bd mass windows, consistent with the background expectation. The resulting upper limits on the branching fractions are B(Bs -> mu+mu-) < 1.5E10-7 and B(Bd -> mu+mu-) < 3.9E-8 at 90% confidence level.

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arXiv2005

Direct Search for Dirac Magnetic Monopoles in p-pbar Collisions at sqrt(s) = 1.96 TeV

We search for pair-produced Dirac magnetic monopoles in 35.7 pb^-1 of proton-antiproton collisions at sqrt(s) = 1.96 TeV with the Collider Detector at Fermilab (CDF). We find no monopole candidates corresponding to a 95% confidence-level cross-section limit sigma < 0.2 pb for a monopole with mass between 200 and 700 GeV/c^2. Assuming a Drell-Yan pair production mechanism, we set a mass limit m>360 GeV/c^2.

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arXiv2005

Combination of CDF and D0 Results on the Top-Quark Mass

The results on the measurements of the top-quark mass, based on the data collected by the Tevatron experiments CDF and DØat Fermilab during {\RunI} from 1992 to 1996 and {\RunII} since 2001, are summarized. The combination of the published {\RunI} and preliminary {\RunII} results, taking correlated uncertainties properly into account, is presented. The resulting preliminary world average for the mass of the top quark is: $\MT=172.7\pm 2.9 \GeVc2$, where the total error consists of a statistical part of $1.7 \GeVc2$ and a systematic part of $2.4 \GeVc2$. Compared to the combination prepared for the LP 2005 conference, this combination for the EPS-HEP 2005 conference includes additional published {\RunI} and preliminary {\RunII} measurements.

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arXiv2005

Combination of CDF and D0 Results on the Top-Quark Mass

The results on the measurements of the top-quark mass, based on the data collected by the Tevatron experiments CDF and DØat Fermilab during Run I from 1992 to 1996, and Run II since 2001 are summarized. The combination of the published Run I and preliminary Run II results, taking correlated uncertainties properly into account, is presented. The resulting preliminary world average for the mass of the top quark is: $\MT=174.3 \pm 3.4 \GeVc2$, where the total error consists of a statistical part of $2.0 \GeVc2$ and a systematic part of $2.8 \GeVc2$.

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arXiv2005

Search for First-Generation Scalar Leptoquarks in $\bm{p \bar{p}}$ collisions at $\sqrt{s}$=1.96 TeV

We report on a search for pair production of first-generation scalar leptoquarks ($LQ$) in $p \bar{p}$ collisions at $\sqrt{s}$=1.96 TeV using an integrated luminosity of 203 $pb^{-1}$ collected at the Fermilab Tevatron collider by the CDF experiment. We observe no evidence for $LQ$ production in the topologies arising from $LQ \bar{LQ} \to eqeq$ and $LQ \bar{LQ} \to eq νq$, and derive 95% C.L. upper limits on the $LQ$ production cross section. %as a function of $β$, where $β$ is the branching fraction for $LQ \to eq$. The results are combined with those obtained from a separately reported CDF search in the topology arising from $LQ\bar{LQ} \to νq νq$ and 95% C.L. lower limits on the LQ mass as a function of $β= BR(LQ \to eq) $ are derived. The limits are 236, 205 and 145 GeV/c$^2$ for $β$ = 1, $β$ = 0.5 and $β$ = 0.1, respectively.

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arXiv2005

K_s^0 and Lambda^0 Production Studies in pbar-p Collisions at sqrt(s)=1800 and 630 GeV

We present a study of the production of K_s^0 and Lambda^0 in inelastic pbar-p collisions at sqrt(s)= 1800 and 630 GeV using data collected by the CDF experiment at the Fermilab Tevatron. Analyses of K_s^0 and Lambda^0 multiplicity and transverse momentum distributions, as well as of the dependencies of the average number and of K_s^0 and Lambda^0 on charged particle multiplicity are reported. Systematic comparisons are performed for the full sample of inelastic collisions, and for the low and high momentum transfer subsamples, at the two energies. The p_T distributions extend above 8 GeV/c, showing a higher than previous measurements. The dependence of the mean K_s^0(Lambda^0) p_T on the charged particle multiplicity for the three samples shows a behavior analogous to that of charged primary tracks.

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arXiv2005

Measurement of the Forward-Backward Charge Asymmetry from W --> e nu Production in p anti-p Collisions at s**(1/2) = 1.96 TeV

We report a measurement of the forward-backward charge asymmetry of electrons from W boson decays in p anti-p collisions at s**(1/2) = 1.96 TeV using a data sample of 170 pb-1 collected by the Collider Detector at Fermilab. The asymmetry is measured as a function of electron rapidity and transverse energy and provides new input on the momentum fraction dependence of the u and d quark parton distribution within the proton.

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arXiv2004

Combination of CDF and D0 Results on the Top-Quark Mass

The results on the measurements of the top-quark mass, based on the data collected by the Tevatron experiments CDF and DO at Fermilab during Run I from 1992 to 1996, are summarized. The combination of the published results, taking correlated uncertainties properly into account, is presented. The resulting world average for the mass of the top quark is: $M_t = 178.0 \pm 4.3 GeV/c^2$, where the total error of consists of a statistical part of $2.7 GeV/c^2$ and a systematic part of $3.3 GeV/c^2$.

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