71 research outputs found
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
Observation of the structure in the Mass Spectrum in cays
No full text7 pages, 2 figures, submited to Phys. Rev. LettInternational audienceThe observation of the structure in decays produced in collisions at \sqrt{s}=1.96~\TeV is reported with a statistical significance greater than 5 standard deviations. A fit to the mass spectrum is performed assuming the presence of a Breit-Wigner resonance. The fit yields a signal of resonance events, and resonance mass and width of 4143.4^{+2.9}_{-3.0}(\mathrm{stat})\pm0.6(\mathrm{syst})~\MeVcc and 15.3^{+10.4}_{-6.1}(\mathrm{stat})\pm2.5(\mathrm{syst})~\MeVcc respectively. The parameters of this resonance-like structure are consistent with values reported from an earlier CDF analysis
Measurements of Direct CP Violating Asymmetries in Charmless Decays of Strange Bottom Mesons and Bottom Baryons
No full textWe report measurements of direct CP-violating asymmetries in charmless decays of neutral bottom hadrons to pairs of charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using a data sample corresponding to 1 fb(-1) of integrated luminosity, we obtain the first measurements of direct CP violation in bottom strange mesons, A(CP)(B-s(0) -> K- pi(+)) = +0.39 + 0.15(stat) +/- 0.08(syst), and bottom baryons, A(CP)(Lambda(0)(b) -> p pi(-)) = 0.03 +/- 0.17(stat) +/- 0.05(syst) and A(CP)(Lambda(0)(b) -> pK(-)) = +0.37 +/- 0.17(stat) +/- 0.03dsyst_. In addition, we measure CP violation in B-0 -> K+ pi(-) decays with 3.5 sigma significance, A(CP)(B-0 -> K+ pi(-)) = -0.086 +/- 0.023(stat) +/- 0.009(syst), in agreement with the current world average. Measurements of branching fractions of B-s(0) -> K+K- and B-0 -> pi(+)pi- decays are also updated
Updated search for the flavor-changing neutral-current decay D0 -> mu+ mu- collisions at sqrt(s)=1.96 TeV
No full textWe report on a search for the flavor-changing neutral-current decay D0 \to {\mu}+ {\mu}- in pp collisions at \surd s = 1.96 TeV using 360 pb-1 of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. A displaced vertex trigger selects long-lived D0 candidates in the {\mu}+ {\mu}-, {\pi}+{\pi}-, and K-{\pi}+ decay modes. We use the Cabibbo-favored D0 \to K-{\pi}+ channel to optimize the selection criteria in an unbiased manner, and the kinematically similar D0 \to{\pi}+ {\pi}- channel for normalization. We set an upper limit on the branching fraction (D0 --> {\mu}+ {\mu}-)We report on a search for the flavor-changing neutral-current decay D0→μ+μ- in pp̅ collisions at √s=1.96 TeV using 360 pb-1 of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. A displaced vertex trigger selects long-lived D0 candidates in the μ+μ-, π+π-, and K-π+ decay modes. We use the Cabibbo-favored D0→K-π+ channel to optimize the selection criteria in an unbiased manner, and the kinematically similar D0→π+π- channel for normalization. We set an upper limit on the branching fraction B(D0→μ+μ-)<2.1×10-7(3.0×10-7) at the 90% (95%) confidence level.Peer reviewe
Measurement of b Hadron Lifetimes in Exclusive Decays Containing a J/Psi in p(p)over-bar Collisions at root s=1.96 TeV
No full textWe report on a measurement of b-hadron lifetimes in the fully reconstructed decay modes B+-> J/psi K+, B-0 -> J/psi K*(892)(0), B-0 -> J/psi K-s(0), and Lambda(0)(b)-> J/psi Lambda(0) using data corresponding to an integrated luminosity of 4.3 fb(-1), collected by the CDF II detector at the Fermilab Tevatron. The measured lifetimes are tau(B+)=[1.639 +/- 0.009(stat)+/- 0.009(syst)]ps, tau(B-0)=[1.507 +/- 0.010(stat)+/- 0.008(syst)]ps, and tau(Lambda(0)(b))=[1.537 +/- 0.045(stat)+/- 0.014(syst)]ps. The lifetime ratios are tau(B+)/tau(B-0)=[1.088 +/- 0.009(stat)+/- 0.004(syst)] and tau(Lambda(0)(b))/tau(B-0)=[1.020 +/- 0.030(stat)+/- 0.008(syst)]. These are the most precise determinations of these quantities from a single experiment
Measurements of branching fraction ratios and CP asymmetries in B±→DCPK± decays in hadron collisions
No full textWe reconstruct B[superscript ±]→DK[superscript ±] decays in a data sample collected by the CDF II detector at the Tevatron collider corresponding to 1 fb[superscript -1] of integrated luminosity. We select decay modes where the D meson decays to either K-π+ (flavor eigenstate) or K[superscript -]K[superscript +], π[superscript -]π[superscript +] (CP-even eigenstates), and measure the direct CP asymmetry A[subscript CP+]=0.39±0.17(stat)±0.04(syst), and the double ratio of CP-even to flavor eigenstate branching fractions R[subscript CP+]=1.30±0.24(stat)±0.12(syst). These measurements will improve the determination of the Cabibbo-Kobayashi-Maskawa angle γ. They are performed here for the first time using data from hadron collisions.United States. Dept. of EnergyNational Science FoundationIstituto Nazionale di Fisica Nucleare of ItalyMinistry of Education, Culture, Sports, Science and Technology of JapanNatural Sciences and Engineering Research Council of CanadaNational Science Council of the Republic of ChinaSwiss National Science FoundationAlfred P. Sloan FoundationBundesministerium für Bildung und Forschung, GermanyKorean Science and Engineering FoundationKorean Research FoundationScience and Technology Facilities Council, United KingdomRoyal Society, United KingdomInstitut National de Physique Nucleaire et Physique des Particules/CNRSRussian Foundation for Basic ResearchMEC (Spain)Slovak R&D AgencyAcademy of Finlan
Search for Randall-Sundrum gravitons in the diphoton channel at CDF
No full textWe report on a search for new particles in the diphoton channel using a data sample of pp̅ collisions at √s=1.96 [square root of s-1.96] TeV collected by the CDF II detector at the Fermilab Tevatron, with an integrated luminosity of 5.4 fb-1 [fb superscript -1]. The diphoton invariant mass spectrum of the data agrees well with the standard model expectation. We set upper limits on the production cross section times branching ratio for the Randall-Sundrum graviton, as a function of diphoton mass. We subsequently derive lower limits on the graviton mass of 459 GeV/c2 [GeV/c superscript 2]and 963 GeV/c2 GeV/c superscript 2], at the 95% confidence level, for coupling parameters (k/M̅ Pl) [k/M̅ subscript P1] of 0.01 and 0.1, respectively.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
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)
Measurement of the cross section for t(t)over-bar production in p(p)over-bar collisions using the kinematics of lepton plus jets events
No full textWe present a measurement of the top pair production cross section in p (p) over bar collisions at root s=1.96 TeV. We collect a data sample with an integrated luminosity of 194 +/- 11 pb(-1) with the CDF II detector at the Fermilab Tevatron. We use an artificial neural network technique to discriminate between top pair production and background processes in a sample of 519 lepton+jets events, which have one isolated energetic charged lepton, large missing transverse energy and at least three energetic jets. We measure the top pair production cross section to be sigma(t (t) over bar)=6.6 +/- 1.1 +/- 1.5 pb, where the first uncertainty is statistical and the second is systematic
Study of multi-muon events produced in p (p)over-bar interactions at root s=1.96 TeV
No full textWe report the results of a study of multi-muon events produced at the Fermilab Tevatron collider and acquired with the CDF II detector using a dedicated dimuon trigger. The production cross section and kinematics of events in which both muon candidates are produced inside the beam pipe of radius 1.5 cm are successfully modeled by known processes which include heavy flavor production. In contrast, we are presently unable to fully account for the number and properties of the remaining events, in which at least one muon candidate is produced outside of the beam pipe, in terms of the same understanding of the CDF II detector, trigger, and event reconstruction
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