3,611 research outputs found

    CP and charge asymmetries at CDF

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    We present CDF results on the branching fractions and time-integrated direct CP asymmetries for B0 and B0s decay modes into pairs of charmless charged hadrons (pions or kaons). We report also the first observation of B0s->DsK mode and the measurement of its branching fraction.Comment: Proceedings of The 2007 Europhysics Conference on High Energy Physics Manchester, England 19-25 July 2007. To be published electronically by IoP Journals. FERMILAB-CONF-07-590-E. Nov 2007. 3p

    Observation of Orbitally Excited B_s Mesons

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    We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let

    Measurement of the Lifetime Difference Between B_s Mass Eigenstates

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    We present measurements of the lifetimes and polarization amplitudes for B_s --> J/psi phi and B_d --> J/psi K*0 decays. Lifetimes of the heavy (H) and light (L) mass eigenstates in the B_s system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time. Using 203 +/- 15 B_s decays, we obtain tau_L = (1.05 +{0.16}/-{0.13} +/- 0.02) ps and tau_H = (2.07 +{0.58}/-{0.46} +/- 0.03) ps. Expressed in terms of the difference DeltaGamma_s and average Gamma_s, of the decay rates of the two eigenstates, the results are DeltaGamma_s/Gamma_s = (65 +{25}/-{33} +/- 1)%, and DeltaGamma_s = (0.47 +{0.19}/-{0.24} +/- 0.01) inverse ps.Comment: 8 pages, 3 figures, 2 tables; as published in Physical Review Letters on 16 March 2005; revisions are for length and typesetting only, no changes in results or conclusion

    First Measurement of the W Boson Mass in Run II of the Tevatron

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    We present a measurement of the W boson mass using 200/pb of data collected in pbar p collisions at sqrt(s) = 1.96 TeV by the CDF II detector at Run II of the Fermilab Tevatron. With a sample of 63964 W -> e nu candidates and 51128 W -> mu nu candidates, we measure M_W = (80413 +- 34 (stat) +- 34 (syst) = 80413 +- 48) MeV/c^2. This is the most precise single measurement of the W boson mass to date.Comment: published version in PR

    Measurement of the mass and lifetime of the Ωb\Omega_b^- baryon

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    A proton-proton collision data sample, corresponding to an integrated luminosity of 3 fb1^{-1} collected by LHCb at s=7\sqrt{s}=7 and 8 TeV, is used to reconstruct 63±963\pm9 ΩbΩc0π\Omega_b^-\to\Omega_c^0\pi^-, Ωc0pKKπ+\Omega_c^0\to pK^-K^-\pi^+ decays. Using the ΞbΞc0π\Xi_b^-\to\Xi_c^0\pi^-, Ξc0pKKπ+\Xi_c^0\to pK^-K^-\pi^+ decay mode for calibration, the lifetime ratio and absolute lifetime of the Ωb\Omega_b^- baryon are measured to be \begin{align*} \frac{\tau_{\Omega_b^-}}{\tau_{\Xi_b^-}} &= 1.11\pm0.16\pm0.03, \\ \tau_{\Omega_b^-} &= 1.78\pm0.26\pm0.05\pm0.06~{\rm ps}, \end{align*} where the uncertainties are statistical, systematic and from the calibration mode (for τΩb\tau_{\Omega_b^-} only). A measurement is also made of the mass difference, mΩbmΞbm_{\Omega_b^-}-m_{\Xi_b^-}, and the corresponding Ωb\Omega_b^- mass, which yields \begin{align*} m_{\Omega_b^-}-m_{\Xi_b^-} &= 247.4\pm3.2\pm0.5~{\rm MeV}/c^2, \\ m_{\Omega_b^-} &= 6045.1\pm3.2\pm 0.5\pm0.6~{\rm MeV}/c^2. \end{align*} These results are consistent with previous measurements.Comment: 11 pages, 5 figures, All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-008.htm

    Search for New Particles Leading to Z+jets Final States in ppˉp\bar{p} Collisions at s=1.96\sqrt{s}=1.96 TeV

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    We present the results of a search for new particles that lead to a \Z boson plus jets in ppˉp\bar{p} collisions at s=1.96\sqrt{s}=1.96 TeV using the Collider Detector at Fermilab (CDF II). A data sample with a luminosity of 1.06 \ifb\ collected using \Z boson decays to eeee and μμ\mu\mu is used. We describe a completely data-based method to predict the dominant background from standard-model \Z+jet events. This method can be similarly applied to other analyses requiring background predictions in multi-jet environments, as shown when validating the method by predicting the background from WW+jets in \ttbar production. No significant excess above the background prediction is observed, and a limit is set using a fourth generation quark model to quantify the acceptance. Assuming BR(bbZ)=100BR(b' \to b\Z) = 100% and using a leading-order calculation of the bb' cross section, bb' quark masses below 268 \gev/c^2 are excluded at 95% confidence level.Comment: To be submitted to PR

    Measurement of σ(Λb)/σ(B0)×BR(ΛbΛcπ)/BR(B0D+π)\sigma(\Lambda_b)/\sigma(B^0) \times BR(\Lambda_b\to\Lambda_c\pi^-) / BR(B^0\to D^+\pi^-) in ppˉp\bar{p} Collisions at s=1.96\sqrt{s}=1.96 TeV

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    We present the first observation of the baryon decay ΛbΛcπ\Lambda_b\to\Lambda_c\pi^- followed by ΛcpKπ+\Lambda_c\to p K^-\pi^+ in 106 pb-1 of ppˉp\bar{p} collisions at s=1.96\sqrt{s} = 1.96 TeV in the CDF experiment. In order to reduce systematic error, the measured rate for Λb\Lambda_b decay is normalized to the kinematically similar meson decay B0D+πB^0\to D^+\pi^- followed by D+π+Kπ+D^+\to\pi^+K^-\pi^+. We report the ratio of production cross sections (σ\sigma) times the ratio of branching fractions (BR) for the momentum region integrated above pT>6p_T > 6 GeV/c and pseudorapidity range η<1.3|\eta| < 1.3: σ(ppˉΛbX)/σ(ppˉB0X)×BR(ΛbΛcπ)/BR(B0D+π)=0.82±0.08(stat)±0.11(syst)±0.22(BR(ΛcpKπ+))\sigma(p\bar{p}\to \Lambda_b X) / \sigma (p\bar{p}\to B^0 X) \times BR(\Lambda_b\to\Lambda_c\pi^-) / BR(B^0\to D^+\pi^-) = 0.82 \pm 0.08(stat) \pm 0.11(syst) \pm 0.22 (BR(\Lambda_c\to p K^-\pi^+)).Comment: Submitted to Phys.Rev.Let

    Aerosol deposition and origin in French mountains estimated with soil inventories of 210Pb and artificial radionuclides

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    Radionuclide inventories were measured in soils from different French mountainous areas: Chaîne des Puys (Massif Central), Eastern Corsica, Jura, Montagne Noire, Savoie, Vosges and Rhine Valley. 210Pb soil inventories were used to estimate long-term (>75 yr) deposition of submicron aerosols. Whereas 210Pb total deposition is explained partly by wet deposition, as demonstrated by increase of 210Pb inventory with annual rainfall; a part of 210Pb in the soils of higher altitude is caused by orographic depositions. Using measurements of radionuclides coming from nuclear aerial weapon tests (137Cs and Pu isotopes), we were able to estimate the origin of aerosols deposited in high-altitude sites and to confirm the importance of occult deposition and feeder–seeder mechanism. Using a simple mass balance model, we estimate that occult deposition and feeder–seeder mechanisms account to more than 50% of total deposition of 210Pb and associated submicron aerosols in French altitude sites

    Charmless b-hadrons decays at CDF

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    We present CDF results on the branching fractions and time-integrated direct CP asymmetries for Bd, Bs and Lb decay modes into pairs of charmless charged hadrons (pions, kaons and protons). The data-set for these measurements amounts to 1fb^{-1} of pbar-p collisions at a center of mass energy 1.96TeV. We report on the first observation of the Bs->Kpi, Lb-ppi and Lb->pK decay modes and on the measurement of their branching fractions and direct CP asymmetries.Comment: 4 pages, 1 figure, 2 tables, proceedings of ICHEP200
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