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The CDF Collaboration

Publications and source records attributed to The CDF Collaboration.

At least 91 records · Page 5Linked to original sources
arXiv2003

Measurement of Prompt Charm Meson Production Cross Sections in p anti-p Collisions at s**(1/2) = 1.96 TeV

We report on measurements of differential cross sections d sigma/d p_t for prompt charm meson production in p anti-p collisions at s**(1/2) = 1.96 TeV using 5.8 +/- 0.3 pb-1 of data from the CDF II detector at the Fermilab Tevatron. The data are collected with a new trigger that is sensitive to the long lifetime of hadrons containing heavy flavor. The charm meson cross sections are measured in the central rapidity region |y| \leq 1 in four fully reconstructed decay modes: D0 --> K- pi+, D*+ -> D0 pi+, D+ --> K- pi+ pi+, D+_s--> phi pi+, and their charge conjugates. The measured cross sections are compared to theoretical calculations.

hep-ex↗
arXiv2002

Search for radiative b-hadron decays in proton-antiproton collisions at sqrt(s) = 1.8 TeV

We have performed a search for radiative b-hadron decays using events produced in proton-antiproton collisions at sqrt(s) = 1.8 TeV and collected by the Collider Detector at Fermilab. The decays we considered were B_d -> K*0(-> K+ pi-) gamma, B_s -> phi(-> K+ K-) gamma, Lambda_b -> Lambda(-> p pi-) gamma, and their charge conjugates. Two independent methods to identify photons from such decays were employed. In the first method, the photon was detected in the electromagnetic calorimeter. In the second method, the photon was identified by an electron-positron pair produced through the external photon conversion before the tracking detector volume. By combining the two methods we obtain upper limits on the branching fractions for the B_d, B_s and Lambda_b radiative decays, which, at the 95% confidence level, are found to be B(B_d -> K*0 gamma) < 1.4 x 10^(-4), B(B_s -> phi gamma) < 1.6 x 10^(-4), and B(Lambda_b -> Lambda gamma) < 1.9 x 10^(-3).

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arXiv2002

Measurement of the Ratio of b Quark Production Cross Sections in Antiproton-Proton Collisions at 630 GeV and 1800 GeV

We report a measurement of the ratio of the bottom quark production cross section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom quarks with transverse momenta greater than 10.75 GeV identified through their semileptonic decays and long lifetimes. The measured ratio sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement with next-to-leading order (NLO) quantum chromodynamics (QCD).

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arXiv2001

Diffractive Dijet Production at sqrt(s)=630 and 1800 GeV at the Fermilab Tevatron

We report a measurement of the diffractive structure function $F_{jj}^D$ of the antiproton obtained from a study of dijet events produced in association with a leading antiproton in $\bar pp$ collisions at $\sqrt s=630$ GeV at the Fermilab Tevatron. The ratio of $F_{jj}^D$ at $\sqrt s=630$ GeV to $F_{jj}^D$ obtained from a similar measurement at $\sqrt s=1800$ GeV is compared with expectations from QCD factorization and with theoretical predictions. We also report a measurement of the $ξ$ ($x$-Pomeron) and $β$ ($x$ of parton in Pomeron) dependence of $F_{jj}^D$ at $\sqrt s=1800$ GeV. In the region $0.035<ξ<0.095$, $|t|<1$ GeV$^2$ and $β<0.5$, $F_{jj}^D(β,ξ)$ is found to be of the form $β^{-1.0\pm 0.1} ξ^{-0.9\pm 0.1}$, which obeys $β$-$ξ$ factorization.

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arXiv2001

Search for Gluinos and Scalar Quarks in $p\bar{p}$ Collisions at $\sqrt{s}=1.8$ TeV using the Missing Energy plus Multijets Signature

We have performed a search for gluinos ($\gls$) and squarks ($\sq$) in a data sample of 84 pb$^{-1}$ of \ppb collisions at $\sqrt{s}$ = 1.8 TeV, recorded by the Collider Detector at Fermilab, by investigating the final state of large missing transverse energy and 3 or more jets, a characteristic signature in R-parity-conserving supersymmetric models. The analysis has been performed `blind', in that the inspection of the signal region is made only after the predictions from Standard Model backgrounds have been calculated. Comparing the data with predictions of constrained supersymmetric models, we exclude gluino masses below 195 \gev (95% C.L.), independent of the squark mass. For the case $\msq \approx \mgls$, gluino masses below 300 \gev are excluded.

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arXiv2000

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 $t\bar{t}$ 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 $176.1\pm 6.6 \gevcc$.

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arXiv1999

Measurement of the Associated $γ+ μ^\pm$ Production Cross Section in $p \bar p$ Collisions at $\sqrt{s} = 1.8$ TeV

We present the first measurement of associated direct photon + muon production in hadronic collisions, from a sample of 1.8 TeV $p \bar p$ collisions recorded with the Collider Detector at Fermilab. Quantum chromodynamics (QCD) predicts that these events are primarily from the Compton scattering process $cg \to cγ$, with the final state charm quark producing a muon. Hence this measurement is sensitive to the charm quark content of the proton. The measured cross section of $29\pm 9 pb^{-1}$ is compared to a leading-order QCD parton shower model as well as a next-to-leading-order QCD calculation.

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arXiv1999

Flavor Tagging and CP-Violation Measurements at the Tevatron

The CDF Collaboration has adapted several heavy flavor tagging techniques and employed them in analyses of time-dependent flavor asymmetries using data from the Tevatron Run I. The tagging algorithms were calibrated using low-P_t inclusive lepton and dilepton trigger data samples. The tagging techniques were applied to a sample of \sim 400 B^0_d/B-bar^0_d -> J/psi K^0_s decays and were used to measure the CP violation parameter, sin(2 Beta). Prospects for future improved measurements of the CP violation parameters at the Tevatron are briefly discussed.

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arXiv1998

Measurement of the lepton charge asymmetry in W-boson decays produced in p-pbar collisions

We describe a measurement of the charge asymmetry of leptons from W boson decays in the rapidity range 0<|y_l|<2.5 using W --> enu, munu events from 110+/-7 pb^{-1}of data collected by the CDF detector during 1992-95. The asymmetry data constrain the ratio of d and u quark momentum distributions in the proton over the x range of 0.006 to 0.34 at Q2 \approx M_W^2. The asymmetry predictions that use parton distribution functions obtained from previously published CDF data in the central rapidity region (0.0<|y_l|<1.1) do not agree with the new data in the large rapidity region (|y_l|>1.1).

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arXiv1998

Search for a Technicolor omega_T Particle in Events with a Photon and a b-quark Jet at CDF

If the Technicolor omega_T particle exists, a likely decay mode is omega_T -> gamma pi_T, followed by pi_T -> bb-bar, yielding the signature gamma bb-bar. We have searched 85 pb^-1 of data collected by the CDF experiment at the Fermilab Tevatron for events with a photon and two jets, where one of the jets must contain a secondary vertex implying the presence of a b quark. We find no excess of events above standard model expectations. We express the result of an exclusion region in the M_omega_T - M_pi_T mass plane.

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arXiv1995

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.

hep-ex↗
arXiv1995

Limits on $WWZ$ and $WWγ$ couplings from $WW$ and $WZ$ production in $p\overline{p}$ collisions at $\sqrt{s} = 1.8$ TeV

Direct limits are set on $WWZ$ and $WWγ$ three-boson couplings in a search for $WW$ and $WZ$ production with high transverse momentum in $p\overline{p}$ collisions at $\sqrt{s} = 1.8$ TeV, using the Collider Detector at Fermilab. The results are in agreement with the SU(2) $\times$ U(1) model of electroweak interactions. Assuming Standard Model $WWγ$ coupling, the the limits are interpreted as direct evidence for a non-zero $WWZ$ coupling at subprocess energies near 500 GeV. Alternatively, assumiong identical $WWZ$ and $WWγ$ couplings, bounds $-0.11 < κ< 2.27$ and $-0.81 < λ< 0.84$ are obtained at $95\%$ CL for a form factor scale 1000 GeV.

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arXiv1995

Measurement of the W Boson Mass

We present a measurement of the mass of the $W$ boson using data collected with the CDF detector during the 1992-93 collider run at the Fermilab Tevatron. A fit to the transverse mass spectrum of a sample of 3268 {\mbox{$W \rightarrow μν$}} events recorded in an integrated luminosity of 19.7 pb$^{-1}$ gives a mass $M_{W}^μ=80.310\pm0.205\mbox{~(stat.)}\pm0.130\mbox{~(syst.)} \ \mbox{GeV/c}^{2}$. A fit to the transverse mass spectrum of a sample of 5718 {\mbox{$W \rightarrow eν$}} events recorded in 18.2 pb$^{-1}$ gives a mass $M_{W}^{e}=80.490\pm0.145\mbox{~(stat.)}\pm0.175\mbox{~(syst.)} \ \mbox{GeV/c}^{2}$. Combining the electron and muon results, accounting for correlated uncertainties, yields a mass $M_{W}=80.410\pm0.180 \ \mbox{GeV/c}^{2}$.

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arXiv1995

Observation of Top Quark Production in Pbar-P Collisions

We establish the existence of the top quark using a 67 pb^-1 data sample of Pbar-P collisions at Sqrt(s) = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). Employing techniques similar to those we previously published, we observe a signal consistent with t-tbar decay to WW b-bbar, but inconsistent with the background prediction by 4.8 sigma. Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. We measure the top quark mass to be 176 +/-8(stat) +/- 10(sys.) GeV/c^2, and the t-tbar production cross section to be 6.8 +3.6 -2.4 pb.

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arXiv1994

Measurement of the Bs Meson Lifetime

The lifetime of the $B_s$ meson is measured using the semileptonic decay $B_s \to D_s^- \ell^+ νX$. The data sample consists of 19.3 pb$^{-1}$ of $p \bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992-1993. There are $76 \pm 8$ $\ell^{+} D_s^{-}$ signal events where the $D_s$ is identified via the decay $D_s^{-} \to ϕπ^{-}$,~$ϕ\to K^+ K^-$. Using these events, the $B_s$ meson lifetime is determined to be $τ_{s} = 1.42^{+ 0.27}_{- 0.23} {\rm (stat)} \pm 0.11 {\rm (syst)}$ ps. A measurement of the $B_s$ lifetime in a low statistics sample of exclusive $B_s \to J/ψϕ$ decays is also presented in this paper.

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