5,617 research outputs found

    J/ψ\psi Production in p+p and d+Au Collisions at SNN\sqrt{S_{NN}} = 200 GeV at STAR

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    We present analysis of J/ψ\psi production over the range 1.0<η<4.2-1.0 < \eta < 4.2 in p+p and d+Au collisions using di-electron data taken during the 2008 run with the STAR experiment at Brookhaven National Laboratory. STAR's unique forward capabilities, especially the Forward Meson Spectrometer electromagnetic calorimeter, allow us the possibility of investigating the intrinsic charm components of the proton wave function using high-xFx_F forward particles produced in asymmetric partonic collisions. Mid-rapidity measurements in d+Au collisions extend our understanding of the mechanisms underlying heavy quarkonium production and its transport through cold nuclear matter.Comment: 4 pages, 3 figures, - to appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

    Measurement of the neutral pion cross section in proton-proton collisions at sqrt{s}=200GeV with PHENIX

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    The inclusive cross section for neutral pion production in the range 1<p_T<13GeV/c in |eta|<0.35 has been measured by the PHENIX experiment in proton-proton collisions at sqrt{s}=200GeV. An NLO pQCD calculation is, within the experimental and theoretical uncertainties, consistent with the measurement.Comment: 4 pages, 4 figures. Talk presented at Quark Matter 2002, Nantes, France, July 18-24, 2002. To appear in the proceedings (Nucl. Phys. A

    Hunting for CDF Multi-Muon "Ghost" Events at Collider and Fixed-Target Experiments

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    In 2008 the CDF collaboration discovered a large excess of events containing two or more muons, at least one of which seemed to have been produced outside the beam pipe. We investigate whether similar "ghost" events could (and should) have been seen in already completed experiments. The CDF di-muon data can be reproduced by a simple model where a relatively light X particle undergoes four-body decay. This model predicts a large number of ghost events in Fermilab fixed-target experiments E772, E789 and E866, applying the cuts optimized for analyses of Drell-Yan events. A correct description of events with more than two muons requires a more complicated model, where two X particles are produced from a very broad resonance Y. This model can be tested in fixed-target experiments only if the cut on the angles, or rapidities, of the muons can be relaxed. Either way, the UA1 experiment at the CERN ppbar collider should have observed O(100) ghost events.Comment: 15 pages, 9 figure

    Measurement of inclusive W and Z cross sections in pp collisions at √s = 7 TeV

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    Journal of High Energy Physics 2011.1 (2011): 080 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)Measurements of inclusive W and Z boson production cross sections in pp collisions at √s = 7 TeV are presented, based on 2.9 pb-1 of data recorded by the CMS detector at the LHC. The measurements, performed in the electron and muon decay channels, are combined to give σ(pp → WX) × B(W → lʋ) = 9.95 ± 0.07 (stat.) ± 0.28 (syst.) ± 1.09 (lumi.) nb and σ(pp → ZX) × B(Z → l +l-) = 0.931 ± 0.026 (stat.) ± 0.023 (syst.) ± 0.102 (lumi.) nb, where ℓ stands for either e or μ. Theoretical predictions, calculated at the next-to-next-to-leading order in QCD using recent parton distribution functions, are in agreement with the measured cross sections. Ratios of cross sections, which incur an experimental systematic uncertainty of less than 4%, are also reporte

    Access to diagnosis and treatment of Chagas disease/infection in endemic and non-endemic countries in the XXI century.

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    In this article, Médicos Sin Fronteras (MSF) Spain faces the challenge of selecting, piecing together, and conveying in the clearest possible way, the main lessons learnt over the course of the last seven years in the world of medical care for Chagas disease. More than two thousand children under the age of 14 have been treated; the majority of whom come from rural Latin American areas with difficult access. It is based on these lessons learnt, through mistakes and successes, that MSF advocates that medical care for patients with Chagas disease be a reality, in a manner which is inclusive (not exclusive), integrated (with medical, psychological, social, and educational components), and in which the patient is actively followed. This must be a multi-disease approach with permanent quality controls in place based on primary health care (PHC). Rapid diagnostic tests and new medications should be available, as well as therapeutic plans and patient management (including side effects) with standardised flows for medical care for patients within PHC in relation to secondary and tertiary level, inclusive of epidemiological surveillance systems

    New Physics in CP-Violating Observables for Beauty

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    After the present establishment of CP-Violation in BdB_{d}-physics, consistency tests of unitarity in the Standard Model and the search of new phenomena are compulsory. I illustrate the way to look for T-violation, without contamination of absorptive parts, in correlated decays in B-factories. BsB_{s}-mixing and penguin-mediated BsB_{s}-decays are of prime importance in hadronic machines to look for new physics.Comment: 10 pages, 4 figures, 3 tables; invited talk at "Beauty 2002", Santiago de Compostela, to appear in the proceeding

    On the B and J/Psi Cross Section Measurements at Ua1 and CDF

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    We analise the implications of the measurement of BB and J/ψJ/\psi inclusive \pt\ distributions performed in ppˉp\bar p collisions by the UA1 and CDF experiments.Comment: 16 pages + 8 topdrawer figs included at the end, Latex, IFUP-TH 2/9

    Low mass lepton pair production in hadron collisions

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    The hadroproduction of lepton pairs with mass QQ and transverse momentum QTQ_T can be described in perturbative QCD by the same partonic subprocesses as prompt photon production. We demonstrate that, like prompt photon production, lepton pair production is dominated by quark-gluon scattering in the region QT>Q/2Q_T>Q/2. This leads to sensitivity to the gluon density in kinematical regimes that are accessible both at collider and fixed target experiments while eliminating the theoretical and experimental uncertainties present in prompt photon production.Comment: Talk given by M. Klasen at the International Conference on the Structure and Interactions of the Photon, PHOTON 99, Freiburg i. Brsg., Germany, May 23-27, 1999. To be published in the proceedings. 6 pages, 6 postscript figure

    Transverse Lepton Polarization in Polarized W Decays

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    Calculations of transverse polarization of leptons in the decay WlνW\rightarrow l\nu with polarized WW's are presented. Planned accelerators will produce enough WW's for observation of the Standard Model contributions to this polarization. One loop corrections to the polarization are given; these are too small to be seen at presently available WW sources. The exchange of Majorons will contribute to these polarizations; these may provide limits on the couplings of these particles to leptons.Comment: 8 pages set in RevTex III and 4 uucompressed figures. This revised version studies polarization effects due to the exchange of charged Majoron doublet

    Multiplicity dependence of correlation functions in \bar{p}p reactions at sqrt(s) = 630 GeV

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    Discussions about Bose-Einstein correlations between decay products of coproduced W-bosons again raise the question about the behaviour of correlations if several strings are produced. This is studied by the multiplicity dependence of correlation functions of particle pairs with like-sign and opposite-sign charge in \bar{p}p reactions at sqrt{s} = 630 GeV.Comment: 11 pages latex, 4 figs, includes elsart.cls, submitted to Phys Lett
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