23 research outputs found

    Search for lepton flavor violating decays of a heavy neutral particle in p-pbar collisions at root(s)=1.8 TeV

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    We report on a search for a high mass, narrow width particle that decays directly to e+mu, e+tau, or mu+tau. We use approximately 110 pb^-1 of data collected with the Collider Detector at Fermilab from 1992 to 1995. No evidence of lepton flavor violating decays is found. Limits are set on the production and decay of sneutrinos with R-parity violating interactions.Comment: Figure 2 fixed. Reference 4 fixed. Minor changes to tex

    Momentum distribution of charged particles in jets in dijet events in p(p)over-bar collisions at root s=1.8 TeV and comparisons to perturbative QCD predictions

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    Inclusive momentum distributions of charged particles in restricted cones around jet axes were measured in dijet events with invariant dijet masses in the range 80 to 600 GeV/c(2). Events were produced at the Fermilab Tevatron in p (p) over bar collisions with a center of mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The results were compared to perturbative QCD calculations carried out in the framework of the modified leading log approximation (MLLA) and assuming local parton-hadron duality. It was shown that the data follow theoretical predictions quite well over the whole range of the jet energies included in this analysis. We extracted the MLLA cutoff scale Q(eff) and found a value of 230+/-40 MeV. The theoretical prediction of E(jet)sin theta(c) scaling, where theta(c) is the cone opening angle, was experimentally observed for the first time. From the MLLA fits to the data, two more parameters were extracted: the ratio of parton multiplicities in gluon and quark jets, r=N-partons(g-jet)/N-partons(q-jet)=1.9+/-0.5, and the ratio of the number of charged hadrons to the number of predicted partons in a jet, K-LPHD(charged)=N-hadrons(charged)/N-partons=0.56+/-0.10

    Search for associated production of Upsilon and vector boson in p(p)over-bar collisions at root(s)over-bar=1.8 TeV

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    We present a search for associated production of the Y(1S) and a vector boson in 83 pb(-1) of p (p) over bar collisions at roots=1.8 TeV collected by the CDF experiment in 1994-1995. We find no evidence of the searched signal in the data, and set upper limits to the production cross sections

    Search for a W(') boson decaying to a top and bottom quark pair in 1.8 TeV p(p)over-bar collisions

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    We report the results of a search for a W(') boson produced in p (p) over bar collisions at a center-of-mass energy of 1.8 TeV using a 106 pb(-1) data sample recorded by the Collider Detector at Fermilab. We observe no significant excess of events above background for a W(') boson decaying to a top and bottom quark pair. In a model where this boson would mediate interactions involving a massive right-handed neutrino (nu(R)) and have standard model strength couplings, we use these data to exclude a W(') boson with mass between 225 and 536 GeV/c(2) at 95\% confidence level for M(W)(')>M(nuR) and between 225 and 566 GeV/c(2) at 95\% confidence level for M(W)(')<M(nuR)

    Search for the supersymmetric partner of the top quark in dilepton events from p(p)over-bar collisions at root s=1.8 TeV

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    We have searched for the supersymmetric partner of the top quark (stop) in 107 pb^{-1} of p-pbar collisions at \sqrt{s}= 1.8 TeV collected by the Collider Detector at Fermilab (CDF). Within the framework of the Minimal Supersymmetric extension of the Standard Model (MSSM) each of the pair-produced stops is assumed to decay into a lepton, bottom quark and supersymmetric neutrino. Such a scenario would give rise to events with two leptons, two hadronic jets, and a substantial imbalance of transverse energy. No evidence of such a stop signal has been found. We calculate a 95% confidence level (C.L.) upper limit on the stop production cross section, which excludes stop masses in the region (80<m_{\stop}<135 GeV/c^2) in the mass plane of stop versus sneutrino.Comment: 7 pages, 5 figures. Submitted to Physical Review Letter

    Central pseudorapidity gaps in events with a leading antiproton at the Fermilab tevatron (p)over-barp collider

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    We report a measurement of the fraction of events with a large pseudorapidity gap Deltaeta within the pseudorapidity region available to the proton dissociation products X in (p) over bar +p--&gt;(p) over bar +X. For a final state (p) over bar of fractional momentum loss xi((p) over bar) and 4-momentum transfer squared t((p) over bar) within 0.063 is found to be 0.246+/-0.001 (stat)+/-0.042 (syst) [0.184+/-0.001 (stat)+/-0.043 (syst)]. Our results are compared with gap fractions measured in minimum bias (p) over barp collisions and with theoretical expectations

    Search for a W(') boson decaying to a top and bottom quark pair in 1.8 TeV p(p)over-bar collisions

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    We report the results of a search for a W(') boson produced in p (p) over bar collisions at a center-of-mass energy of 1.8 TeV using a 106 pb(-1) data sample recorded by the Collider Detector at Fermilab. We observe no significant excess of events above background for a W(') boson decaying to a top and bottom quark pair. In a model where this boson would mediate interactions involving a massive right-handed neutrino (nu(R)) and have standard model strength couplings, we use these data to exclude a W(') boson with mass between 225 and 536 GeV/c(2) at 95% confidence level for M(W)(')>M(nuR) and between 225 and 566 GeV/c(2) at 95% confidence level for M(W)(')<M(nuR)

    Management of dyslipidaemia in patients with coronary heart disease: Results from the ESC-EORP EUROASPIRE V survey in 27 countries

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    Background and aims: One of the objectives of the ESC-EORP EUROASPIRE V survey is to determine how well European guidelines on the management of dyslipidaemias are implemented in coronary patients. Methods: Standardized methods were used by trained technicians to collect information on 7824 patients from 130 centers in 27 countries, from the medical records and at a visit at least 6 months after hospitalization for a coronary event. All lipid measurements were performed in one central laboratory. Patients were divided into three groups: on high-intensity LDL-C-lowering-drug therapy (LLT), on low or moderate-intensity LLT and on no LLT. Results: At the time of the visit, almost half of the patients were on a high-intensity LLT. Between hospital discharge and the visit, LLT had been reduced in intensity or interrupted in 20.8\% of the patients and had been started or increased in intensity in 11.7\%. In those who had interrupted LLT or had reduced the intensity, intolerance to LLT and the advice of their physician were reported as the reason why in 15.8 and 36.8\% of the cases, respectively. LDL-C control was better in those on a high-intensity LLT compared to those on low or moderate intensity LLT. LDL-C control was better in men than women and in patients with self-reported diabetes. Conclusions: The results of the EUROASPIRE V survey show that most coronary patients have a less than optimal management of LDL-C. More professional strategies are needed, aiming at lifestyle changes and LLT adapted to the need of the individual patient

    Recent photoproduction results from ZEUS

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    Recent results for inclusive jet cross sections, dijet cross sections and dijet angular distributions are compared with NLO perturbative QCD calculations. The observation of isolated high PT photons (prompt photons) is also reported

    Leading baryons at low x(L) in DIS and photoproduction at ZEUS

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    Results obtained by the ZEUS collaboration on leading baryon production in the proton fragmentation region are presented. The reaction gamma p --> NX, with N a proton or a neutron, is examined both at low and high photon virtuality
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