49 research outputs found

    Analytic Methods in Nonperturbative QCD

    Full text link
    Recently developed analytic methods in the framework of the Field Correlator Method are reviewed in this series of four lectures and results of calculations are compared to lattice data and experiment. Recent lattice data demonstrating the Casimir scaling of static quark interaction strongly support the FCM and leave very little space for all other theoretical models, e.g. instanton gas/liquid model. Results of calculations for mesons, baryons, quark-gluon plasma and phase transition temperature demonstrate that new analytic methods are a powerful tool of nonperturbative QCD along with lattice simulations.Comment: LaTeX, 34 pages; Lectures given at the 13th Indian-Summer School "Understanding the Structure of Hadrons", August 28 - September 1, 2000, Prague, Czech Republi

    Measurement of RudsR_{\text{uds}} and RR between 3.12 and 3.72 GeV at the KEDR detector

    Get PDF
    Using the KEDR detector at the VEPP-4M e+e−e^+e^- collider, we have measured the values of RudsR_{\text{uds}} and RR at seven points of the center-of-mass energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or better than 3.3%3.3\% at most of energy points with a systematic uncertainty of about 2.1%2.1\%. At the moment it is the most accurate measurement of R(s)R(s) in this energy range

    New precise determination of the \tau lepton mass at KEDR detector

    Full text link
    The status of the experiment on the precise τ\tau lepton mass measurement running at the VEPP-4M collider with the KEDR detector is reported. The mass value is evaluated from the τ+τ−\tau^+\tau^- cross section behaviour around the production threshold. The preliminary result based on 6.7 pb−1^{-1} of data is mτ=1776.80−0.23+0.25±0.15m_{\tau}=1776.80^{+0.25}_{-0.23} \pm 0.15 MeV. Using 0.8 pb−1^{-1} of data collected at the ψâ€Č\psi' peak the preliminary result is also obtained: ΓeeBττ(ψâ€Č)=7.2±2.1\Gamma_{ee}B_{\tau\tau}(\psi') = 7.2 \pm 2.1 eV.Comment: 6 pages, 8 figures; The 9th International Workshop on Tau-Lepton Physics, Tau0

    Measurement of \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-) and \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)

    Get PDF
    The products of the electron width of the J/\psi meson and the branching fraction of its decays to the lepton pairs were measured using data from the KEDR experiment at the VEPP-4M electron-positron collider. The results are \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-)=(0.3323\pm0.0064\pm0.0048) keV, \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)=(0.3318\pm0.0052\pm0.0063) keV. Their combinations \Gamma_{ee}\times(\Gamma_{ee}+\Gamma_{\mu\mu})/\Gamma=(0.6641\pm0.0082\pm0.0100) keV, \Gamma_{ee}/\Gamma_{\mu\mu}=1.002\pm0.021\pm0.013 can be used to improve theaccuracy of the leptonic and full widths and test leptonic universality. Assuming e\mu universality and using the world average value of the lepton branching fraction, we also determine the leptonic \Gamma_{ll}=5.59\pm0.12 keV and total \Gamma=94.1\pm2.7 keV widths of the J/\psi meson.Comment: 7 pages, 6 figure

    Search for narrow resonances in e+ e- annihilation between 1.85 and 3.1 GeV with the KEDR Detector

    Full text link
    We report results of a search for narrow resonances in e+ e- annihilation at center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR detector at the VEPP-4M e+ e- collider. The upper limit on the leptonic width of a narrow resonance Gamma(R -> ee) Br(R -> hadr) < 120 eV has been obtained (at 90 % C.L.)

    Measurement of main parameters of the \psi(2S) resonance

    Get PDF
    A high-precision determination of the main parameters of the \psi(2S) resonance has been performed with the KEDR detector at the VEPP-4M e^{+}e^{-} collider in three scans of the \psi(2S) -- \psi(3770) energy range. Fitting the energy dependence of the multihadron cross section in the vicinity of the \psi(2S) we obtained the mass value M = 3686.114 +- 0.007 +- 0.011 ^{+0.002}_{-0.012} MeV and the product of the electron partial width by the branching fraction into hadrons \Gamma_{ee}*B_{h} = 2.233 +- 0.015 +- 0.037 +- 0.020 keV. The third error quoted is an estimate of the model dependence of the result due to assumptions on the interference effects in the cross section of the single-photon e^{+}e^{-} annihilation to hadrons explicitly considered in this work. Implicitly, the same assumptions were employed to obtain the charmonium leptonic width and the absolute branching fractions in many experiments. Using the result presented and the world average values of the electron and hadron branching fractions, one obtains the electron partial width and the total width of the \psi(2S): \Gamma_{ee} =2.282 +- 0.015 +- 0.038 +- 0.021 keV, \Gamma = 296 +- 2 +- 8 +- 3 keV. These results are consistent with and more than two times more precise than any of the previous experiments

    Heavy quarkonium: progress, puzzles, and opportunities

    Get PDF
    A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the BB-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

    New precision measurement of the J/ψJ/\psi- and ψâ€Č\psi' -meson masses

    Full text link
    A new high precision measurement of the J/ψJ/\psi- and ψâ€Č\psi'-meson masses has been performed at the VEPP-4M collider using the KEDR detector. The resonant depolarization method has been employed for the absolute calibration of the beam energy. The following mass values have been obtained: MJ/ψ=3096.917±0.010±0.007M_{J/\psi} = 3096.917 \pm 0.010 \pm 0.007 MeV, Mψâ€Č=3686.111±0.025±0.009M_{\psi'} = 3686.111 \pm 0.025 \pm 0.009 MeV. The relative measurement accuracy has reached 4.10−64. 10^{-6} for J/ψJ/\psi and 7.10−67. 10^{-6} for ψâ€Č\psi', approximately 3 times better than in the previous precise experiments.Comment: 12 pages, 4 tables, 10 figure

    The dependence of the reproductive qualities of beef-cows on the Body Condition Scoring

    No full text
    A comparative assessment of the reproductive qualities of beef-cows of the Hereford and Kazakh white-headed breeds is given, depending on the Body Condition Scoring. In the scientific and economic experiment in three farms on 3 groups of cows of two breeds, the influence of Body Condition Scoring on the reproductive qualities of cows was studied. It was found that cows with a Body Condition Scoring of 6 points have a significantly shorter service period (by 10-13 days) and the interval between calving (by 6-9 days), with an increase in the duration of pregnancy by 2-4 days, compared with cows with a score of 3 points. The calf crop per 100 cows, in groups with 6 Body Condition Scoring points, was higher than in groups with 3 Body Condition Scoring points by 9.2, 8.3 and 5.1%
    corecore