68 research outputs found

    Usefulness of the updated logistic clinical SYNTAX score after percutaneous coronary intervention in patients with prior coronary artery bypass graft surgery: Insights from the GLOBAL LEADERS trial

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    Objectives: We aimed to investigate the prognostic utility of the anatomical CABG SYNTAX and logistic clinical SYNTAX scores for mortality after percutaneous coronary intervention (PCI) in patients with prior coronary artery bypass grafts (CABG). Background: The anatomical SYNTAX score evaluated the anatomical complexity of coronary artery disease and helped predict the prognosis of patients undergoing PCI. The anatomical CABG SYNTAX score was derived from the anatomical SYNTAX score in patients with prior CABG, whilst the logistic clinical SYNTAX score was developed by incorporating clinical factors into the anatomical SYNTAX score. Methods: We calculated the anatomical CABG SYNTAX score and logistic clinical SYNTAX score in 205 patients in the GLOBAL LEADERS trial. The predictive abilities of these scores for 2-year all-cause mortality were evaluated. Results: Using the median scores as categorical thresholds between low and high score groups, the logistic clinical SYNTAX score was able to discriminate the risk of 2-year mortality, unlike the anatomical CABG SYNTAX score. The logistic clinical SYNTAX was significantly better at predicting 2-year mortality, compared to the anatomical CABG SYNTAX score, as evidenced by AUC values in receiver-operating characteristic curve analysis (0.806 vs. 0.582, p <.001) and integrated discrimination improvement (0.121, p <.001). Conclusions: The logistic clinical SYNTAX score was superior to the anatomical CABG SYNTAX score in predicting 2-year mortality

    First Measurement of the Strange Quark Asymmetry at the Z0Z^{0} Peak

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    Measurement of inclusive π0\pi^{0} production in hadronic Z0Z^{0} decays

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    An analysis is presented of inclusive \pi^0 production in Z^0 decays measured with the DELPHI detector. At low energies, \pi^0 decays are reconstructed by \linebreak using pairs of converted photons and combinations of converted photons and photons reconstructed in the barrel electromagnetic calorimeter (HPC). At high energies (up to x_p = 2 \cdot p_{\pi}/\sqrt{s} = 0.75) the excellent granularity of the HPC is exploited to search for two-photon substructures in single showers. The inclusive differential cross section is measured as a function of energy for {q\overline q} and {b \bar b} events. The number of \pi^0's per hadronic Z^0 event is N(\pi^0)/ Z_{had}^0 = 9.2 \pm 0.2 \mbox{(stat)} \pm 1.0 \mbox{(syst)} and for {b \bar b}~events the number of \pi^0's is {\mathrm N(\pi^0)/ b \overline b} = 10.1 \pm 0.4 \mbox{(stat)} \pm 1.1 \mbox{(syst)} . The ratio of the number of \pi^0's in b \overline b events to hadronic Z^0 events is less affected by the systematic errors and is found to be 1.09 \pm 0.05 \pm 0.01. The measured \pi^0 cross sections are compared with the predictions of different parton shower models. For hadronic events, the peak position in the \mathrm \xi_p = \ln(1/x_p) distribution is \xi_p^{\star} = 3.90^{+0.24}_{-0.14}. The average number of \pi^0's from the decay of primary \mathrm B hadrons is found to be {\mathrm N} (B \rightarrow \pi^0 \, X)/\mbox{B hadron} = 2.78 \pm 0.15 \mbox{(stat)} \pm 0.60 \mbox{(syst)}

    Search for Neutral Heavy Leptons Produced in Z Decays

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    Weak isosinglet Neutral Heavy Leptons (νm\nu_m) have been searched for using data collected by the DELPHI detector corresponding to 3.3×1063.3\times 10^{6} hadronic~Z0^{0} decays at LEP1. Four separate searches have been performed, for short-lived νm\nu_m production giving monojet or acollinear jet topologies, and for long-lived νm\nu_m giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(BR(Z0νmν)^0\rightarrow \nu_m \overline{\nu}) of about 1.3×1061.3\times10^{-6} at 95\% confidence level for νm\nu_m masses between 3.5 and 50 GeV/c2c^2. Outside this range the limit weakens rapidly with the νm\nu_m mass. %Special emphasis has been given to the search for monojet--like topologies. One event %has passed the selection, in agreement with the expectation from the reaction: %e+eˉννˉe^+e^- \rightarrow\ell \bar\ell \nu\bar\nu. The results are also interpreted in terms of limits for the single production of excited neutrinos

    Energy dependence of the differences between the quark and gluon jet fragmentation

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    Three jet events arising from decays of the Z boson, collected by the DELPHI detector, were used to measure differences in quark and gluon fragmentation. Gluon jets were anti-tagged by identifying b quark jets. Unbiased quark jets came from events with two jets plus one photon. Quark and gluon jet properties in different energy ranges were compared for the first time within the same detector. Quark and gluon jets of nearly the same energy in symmetric three jet event topologies were also compared. Using three independent methods, the average value of the ratio of the mean charged multiplicities of gluon and quark jets is =1.241±0.015 (stat.)±0.025 (syst.). =1.241\pm 0.015\ (stat.) \pm 0.025\ (syst.). Gluon jets are broader and produce fragments with a softer energy spectrum than quark jets of equivalent energy. The string effect has been observed in fully symmetric three jet events. The measured ratio R_{\gamma} of the charged particle flow in the q\overline{q} inter-jet region of the q\bar{q}g and q\bar{q}\gamma samples agrees with the perturbative QCD expectation. The dependence of the mean charged multiplicity on the hadronic center-of-mass energy was analysed in photon plus n-jet events. The value for \alpha_s(M_Z) determined from these data using a QCD prediction with corrections at leading and next-to-leading order is \[ \alpha_s(M_Z)=0.116 \pm 0.003\ (stat.) \pm 0.009\ (syst.). \

    Search for new phenomena using single photon events in the DELPHI detector at LEP

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    Data are presented on the reaction \epem~\into~\gamma + no other detected particle at center-of-mass energies, \sqs = 89.48 GeV, 91.26 GeV and 93.08 GeV. The cross section for this reaction is related directly to the number of light neutrino generations which couple to the \zz boson, and to several other phenomena such as excited neutrinos, the production of an invisible `X' particle, a possible magnetic moment of the tau neutrino, and neutral monojets. Based on the observed number of single photon events, the number of light neutrinos which couple to the \zz is measured to be N_\nu = 3.15 \pm 0.34. No evidence is found for anomalous production of energetic single photons, and upper limits at the 95\% confidence level are determined for excited neutrino production (BR < 4-9 \times 10^{-6}), production of an invisible `X' particle (\sigma < 0.1 pb), and the magnetic moment of the tau neutrino (< 5.2 \times 10^{-6} \mu_B). No event with the topology of a neutral monojet is found, and this corresponds to the limit \sigma < 0.044/\epsilon pb at the 95\% confidence level, where \epsilon is the unknown overall monojet detection efficiency

    Measurement of the Bd0^{0}_{d} oscillation frequency using kaons, leptons and jet charge

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    A measurement of the mass difference, \Delta m_d, between the two physical \mbox{B}^0_d states has been obtained from the analysis of the impact parameter distribution of a lepton emitted at large transverse momentum (p_t) relative to the jet axis and from the analysis of the flight distance distribution of secondary vertices tagged by either a high p_t lepton or an identified kaon. In the opposite hemisphere of the event, the charge of the initial quark has been evaluated using a high p_t lepton, a charged kaon or the mean jet charge. With 1.7 million hadronic Z^0 decays recorded by DELPHI between 1991 and 1993, \Delta m_d is found to be: \Delta m_d = 0.531^{+0.050}_{-0.046} ~(stat.) \pm 0.078 ~(syst.) ~ {\mathrm{ps}}^{-1} \,

    Search for Lepton Flavour Number violating Z0Z^0-Decays

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    A search for lepton flavour number violating Z0Z^0 decays in the channels \begin{center} Z0μτZ^0\rightarrow \mu\tau,\\ Z0eτZ^0\rightarrow e\tau, \\ Z0eμZ^0\rightarrow e\mu, \\ \end{center} using the DELPHI detector with data collected during the 1991--94 LEP runs, is described. No signal was found. Upper limits at 95\% confidence level for the respective branching fractions of 1.2×1051.2\times 10^{-5}, 2.2×1052.2\times 10^{-5}, and 0.25×1050.25\times 10^{-5}, were obtained
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