27 research outputs found
Measurement of d sigma/dy of Drell-Yan e(+)e(-) pairs in the Z mass region from p(p)over-bar collisions at root s=1.96 TeV
No full textWe report on a CDF measurement of the total cross section and rapidity distribution, d sigma/dy, for gamma*/Z -\u3e e(+)e(-) events in the Z boson mass region (66 \u3c M-ee \u3c 116 GeV/c(2)) produced in p (p) over bar collisions at root s = 1.96 TeV with 2.1 fb(-1) of integrated luminosity. The measured cross section of 257 +/- 16 pb and d sigma/dy distribution are compared with Next-to-Leading-Order (NLO) and Next-to-Next-to-Leading-Order (NNLO) QCD theory predictions with CTEQ and MRST/MSTW parton distribution functions (PDFs). There is good agreement between the experimental total cross section and d sigma/dy measurements with theoretical calculations with the most recent NNLO PDFs. (C) 2010 Elsevier B.V. All rights reserved
Combination of CDF and D0 results on the W boson mass and width
No full textThe results based on 1992–95 data (Run 1) from the CDF and D0 experiments on the measurements of the W boson mass and width are presented, along with the combined results. We report a Tevatron collider average MW=80.456±0.059  GeV. We also report the Tevatron collider average of the directly measured W boson width ΓW=2.115±0.105  GeV. We describe a new joint analysis of the direct W mass and width measurements. Assuming the validity of the standard model, we combine the directly measured W boson width with the width extracted from the ratio of W and Z boson leptonic partial cross sections. This combined result for the Tevatron is ΓW=2.135±0.050  GeV. Finally, we use the measurements of the direct total W width and the leptonic branching ratio to extract the leptonic partial width Γ(W→eν)=224±13  MeV
Production of Λ[superscript 0], Λ̅ [superscript 0], Ξ[superscript ±], and Ω[superscript ±] hyperons in pp̅ collisions at √s=1.96 TeV
No full textWe report a set of measurements of inclusive invariant pT differential cross sections of Λ[superscript 0], Λ̅ [superscript 0], Ξ[superscript ±], and Ω[superscript ±] hyperons reconstructed in the central region with pseudorapidity |η|<1 and p[subscript T] up to 10 GeV/c. Events are collected with a minimum-bias trigger in pp̅ collisions at a center-of-mass energy of 1.96 TeV using the CDF II detector at the Tevatron Collider. As p[subscript T] increases, the slopes of the differential cross sections of the three particles are similar, which could indicate a universality of the particle production in p[subscript T]. The invariant differential cross sections are also presented for different charged-particle multiplicity intervals
Improved determination of the sample composition of dimuon events produced in p(p)over-bar collisions at root s=1.96 TeV
No full textWe use a new method to estimate with 5% accuracy the contribution of pion and kaon in-flight-decays to the dimuon data set acquired with the CDF detector. Based on this improved estimate, we show that the total number and the properties of the collected dimuon events are not yet accounted for by ordinary sources of dimuons which also include the contributions, as measured in the data, of heavy flavor, Υ{hooked}, and Drell-Yan production in addition to muons mimicked by hadronic punchthrough. The number of unaccounted events corresponds to (12.8±3.2)% of the bb̄ production. We find that (23±6)% of the unaccounted events contain additional muon candidates. For comparison, this fraction is (6.9±0.4)% for events due to bb̄ production. © 2011 The Author(s)
Observation of Bs0→J/ψK*(892)0 [B subscript s superscript 0 → J / psi K* (892) superscript 0] and Bs0→J/ψKS0 [B subscript s superscript 0 → J / psi K subscript s superscript 0 ] decays
No full textWe report the first observation of two Cabibbo-suppressed decay modes of the Bs0 [B subscript s superscript 0] meson. Using a sample of pp̅ collisions at √s=1.96 [square root of 1.96] TeV corresponding to 5.9 fb-1 [fb superscript -1] of integrated luminosity collected with the CDF II, the collider detector at the Fermilab Tevatron, we search for new Bs0 [B subscript s superscript 0] decay modes in a sample of events containing J/ψ→μ+μ- [J / psi→mu superscript + mu superscript -] decays. We reconstruct a Bs0→J/ψK*(892)0 [B subscript s superscript 0→J / psi K subscript s superscript 0] signal with K*(892)0→K+π- [K* (892) superscript 0 →K superscript + pi superscript -], observing a yield of 151±25 events with a statistical significance of 8.0σ [8.0 delta]. We also reconstruct a Bs0→J/ψKS0 [B subscript s superscript 0→J / psi K subscript s superscript 0] signal with KS0→π+π- [K subscript s superscript 0→ pi superscript + pi superscript -], observing a yield of 64±14 events with a statistical significance of 7.2σ [7.2 delta]. From these yields, we extract the branching ratios B(Bs0→J/ψK*(892)0)=(8.3±3.8)×10-5 [B (B subscript s superscript 0→J / psi K* (892) superscript 0) = (8.3±3.8) × 10 superscript -5] and B(Bs0→J/ψK0)=(3.5±0.8)×10-5 [B (B subscript s superscript 0→J / psi K superscript 0) = (3.5 ± 0.8) × 10 superscript -5], where statistical, systematic, and fragmentation-fraction uncertainties are included in the combined uncertainty.United States. Dept. of EnergyNational Science foundation (U.S.)Alfred P. Sloan Foundatio
Search for new heavy particles decaying to ZZ→llll, lljj in pp̅ collisions at √s=1.96 [square root of s=1.96] TeV
No full textWe report on a search for anomalous production of Z boson pairs through a massive resonance decay in data corresponding to 2.5–2.9 fb-1 [fb superscript -1] of integrated luminosity in pp̅ collisions at √s=1.96 [square root of s=1.96] TeV using the CDF II detector at the Fermilab Tevatron. This analysis, with more data and channels where the Z bosons decay to muons or jets, supersedes the 1.1 fb-1 [fb superscript -1] four-electron channel result previously published by CDF. In order to maintain high efficiency for muons, we use a new forward tracking algorithm and muon identification requirements optimized for these high signal-to-background channels. Predicting the dominant backgrounds in each channel entirely from sideband data samples, we observe four-body invariant mass spectra above 300 GeV/c2 [GeV / c superscript 2] that are consistent with background. We set limits using the acceptance for a massive graviton resonance that are 7–20 times stronger than the previously published direct limits on resonant ZZ diboson production.United States. Dept. of Energy.National Science Foundation (U.S.)Alfred P. Sloan Foundatio
Search for the rare radiative decay W→πγ in pp̅ collisions at √s=1.96 TeV
No full textWe present a search for the rare radiative decay W[superscript ±]→π[superscript ±]γ using data corresponding to an integrated luminosity of 4.3 fb[superscript -1] of proton-antiproton collisions at a center-of-mass energy of 1.96 TeV collected by the CDF experiment at Fermilab. As no statistically significant signal is observed, we set a 95%-confidence-level upper limit on the relative branching fraction Γ(W[superscript ±]→π[superscript ±]γ)/Γ(W[superscript ±]→e[superscript ±]ν) at 6.4×10[superscript -5], a factor of 10 improvement over the previous limit.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
Evidence for tt̅ γ production and measurement of σtt̅ γ/σtt
No full textUsing data corresponding to 6.0 fb[superscript -1] of pp̅ collisions at √s=1.96 TeV collected by the CDF II detector, we present a cross section measurement of top-quark pair production with an additional radiated photon in the central region with 10 GeV or more of transverse energy tt̅ γ. The events are selected by looking for a lepton (ℓ or μ), a photon (γ), significant transverse momentum imbalance (E̸T), large total transverse energy, and three or more jets, with at least one identified as containing a b quark (b). Using an event selection optimized for the tt̅ γ candidate sample, we also measure the cross section of tt̅ (σtt̅ ). We measure the tt̅ γ cross section (σtt̅ γ) to be 0.18±0.08 pb, and the ratio of σtt̅ γ to σtt̅ to be 0.024±0.009. We observe a probability of 0.0015 (3.0 standard deviations) of the background (non-tt̅ γ events alone producing 30 events or more.National Science Foundation (U.S.)United States. Dept. of Energ
Measurement of the Bs0 Lifetime in Fully and Partially Reconstructed Bs0→Ds-(ϕπ-)X Decays in p̅ p Collisions at √s=1.96 TeV
No full textWe present a measurement of the B[subscript s][superscript 0] lifetime in fully and partially reconstructed B[subscript s][superscript 0]→D[subscript s][superscript -](ϕπ[superscript -])X decays in 1.3 fb[superscript -1] collected in pp̅ collisions at √s=1.96 TeV by the CDF II detector at the Fermilab Tevatron. We measure τ(B[subscript s][superscript 0])=1.518±0.041(stat)±0.027(syst) ps. The ratio of this result and the world average B[superscript 0] lifetime yields τ(B[subscript s][superscript 0])/τ(B[superscript 0])=0.99±0.03, which is in agreement with recent theoretical predictions.National Science Foundation (U.S.)United States. Dept. of EnergyAlfred P. Sloan Foundatio
Measurements of the properties of Λc(2595), Λc(2625), Σc(2455), and Σc(2520) baryons
No full textWe report measurements of the resonance properties of Lambdac(2595)+ and Lambdac(2625)+ baryons in their decays to Lambdac+pi+- as well as Sigmac(2455)++,0 and Sigmac(2520)++,0 baryons in their decays to Lambdac+pi± final states. These measurements are performed using data corresponding to 5.2 f[superscript -1] of integrated luminosity from pp[over-bar] collisions at [sqrt]s=1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. Exploiting the largest available charmed baryon sample, we measure masses and decay widths with uncertainties comparable to the world averages for Sigmac states, and significantly smaller uncertainties than the world averages for excited Λc+ states.Alfred P. Sloan FoundationUnited States. Dept. of EnergyNational Science Foundation (U.S.
