1,629 research outputs found

    Statistical J/psi production and open charm enhancement in Pb+Pb collisions at CERN SPS

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    Production of open and hidden charm hadrons in heavy ion collisions is considered within the statistical coalescence model. Charmed quarks and antiquarks are assumed to be created at the initial stage of the reaction and their number is conserved during the evolution of the system. They are distributed among open and hidden charm hadrons at the hadronization stage in accordance with laws of statistical mechanics. The model is in excellent agreement with the experimental data on J/psi production in lead-lead collisions at CERN SPS and predicts strong enhancement of the open charm multiplicity over the standard extrapolation from nucleon-nucleon to nucleus-nucleus collisions. A possible mechanism of the charm enhancement is proposed.Comment: Presented at 6th International Conference on Strange Quarks in Matter, Frankfurt am Main, 2001. 4 pages, LaTeX, 1 PS-figur

    Evidence for psi' regeneration in heavy ion collisions

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    The study of hidden charm production is an important part of the heavy ion program. The standard approach to this problem [1] assumes that cÂŻc bound states are created only at the initial stage of the reaction and then partially destroyed at later stages due to interactions with the medium [2, 3, 4]

    The Breathing Modes of the B=2B=2 Skyrmion and the Spin-Orbit Interaction

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    The coupling of the breathing and rotational modes of the skyrmion-skyrmion system leads to a nucleon-nucleon spin-orbit interaction of short range, as well as to spin-orbit potentials for the transitions NN→N(1440)NNN \to N(1440)N, NN→NN(1440)NN \to NN(1440) and NN→N(1440)N(1440)NN \to N(1440)N(1440). The longest range behaviour of these spin-orbit potentials is calculated in closed form.Comment: Latex, figures not include
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