18,491 research outputs found

    Applications of Nonrelativistic Effective Field Theories to quarkonium systems with a small radius

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    We review some predictions of nonrelativistic effective field theories for heavy quark-antiquark systems with a small typical radius, r<1/\Lambda_QCD.Comment: 4 pages, uses espcrc2.sty, talk given at the BEACH2002 Conference, Vancouver, June 200

    Effective Field Theories for Heavy Quarkonium

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    We briefly review how nonrelativistic effective field theories give us a definition of the QCD potentials and a coherent field theory derived quantum mechanical scheme to calculate the properties of bound states made by two or more heavy quarks. In this framework heavy quarkonium properties depend only on the QCD parameters (quark masses and \als) and nonpotential corrections are systematically accounted for. The relation between the form of the nonperturbative potentials and the low energy QCD dynamics is also discussed.Comment: Invited Plenary talk at The 20th European Conference on Few-Body Problems in Physics. September 10-14 2007. Pisa, Italy. To be published on Few-Body System

    New results on inclusive quarkonium decays

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    I review some recent progress, leading to a substantial reduction in the number of non-perturbative parameters, in the calculation of inclusive quarkonium decay widths in the framework of non-relativistic effective field theories.Comment: 4 pages, 3 figures, to be published in the proceedings of the XXXVIIth Rencontres de Moriond (QCD and High Energy Hadronic Interactions), 16-23 March 2002, Les Arcs, Franc

    Three-body relativistic flux tube model from QCD Wilson-loop approach

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    First we review the derivation of the relativistic flux tube model for a quark-antiquark system from Wilson area law as we have given in a preceding paper. Then we extend the method to the three-quark case and obtain a Lagrangian corresponding to a star flux tube configuration. A Hamiltonian can be explicitly constructed as an expansion in 1/m21 / m^2 or in the string tension σ\sigma. In the first case it reproduces the Wilson loop three-quark semirelativistic potential; in the second one, very complicated in general, but it reproduces known string models for slowly rotating quarks.Comment: 14 pages, latex, uses elsart.sty, 2 figures available upon reques

    The qqˉq \bar{q} relativistic interaction in the Wilson loop approach

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    We study the qqˉq \bar{q} relativistic interaction starting from the Feynman-Schwinger representation of the gauge-invariant quark-antiquark Green function. We focus on the one-body limit and discuss the obtained non-perturbative interaction kernel of the Dirac equation.Comment: 5 pages, Latex (espcrc2.sty) To be published in the proceedings of High-Energy Physics International Euroconference on Quantum Chromodynamics:QCD97; 25th Anniversary of QCD, Montpellier, France, 3-9 July 199

    The non-perturbative QCD potential

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    The potential between heavy quarks can be rigorously defined in a QCD effective field theories framework. I discuss the general situation when the coupling constant may not be considered small and provide an explicit expression for the potential valid up to order 1/m^2. Spin dependent and spin independent terms are expressed in terms of Wilson loops, completing an ideal journey started twenty years ago with the classical work of Eichten and Feinberg.Comment: 8 pages, 1 figure, espcrc2.sty. Invited talk given at QCD00, 6-13 July, Montpellier, France and at the XIII International Workshop on the Fundamental Problems of High Energy Physics and Field Theory, 21-23 June, Protvino, Russia. To be published in Nucl. Phys. Proc. Supp

    Probing the QCD vacuum

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    Heavy quark bound states are used as significative probes of the QCD vacuum and the mechanism of confinement.Comment: 13 pages, sprocl.sty, 2 figures, Invited talk given at the XVIII Autumn School ``Topology of Strongly Correlated Systems'', Lisbon, Portugal, 8-13 October, 200

    Optical fibre nanowire technology and applications

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    A review of optical fibre nanowires and their applications is presented