475 research outputs found

    Comparison of Nuclear Suppression Effects on Meson Production at High p_T and p_L

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    The medium effect on the pion distribution at high pTp_T in AAAA collisions is compared to that of the pion distribution at high pLp_L in pApA collisions. Both the suppression of the spectra and the energy losses of the measured pions are studied. Although the medium effect on pTp_T is larger than on pLp_L, the difference is found surprisingly to be not as big as one would naively expect.Comment: 8 RevTex pages with 5 figure

    Color mixing in high-energy hadron collisions

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    The color mixing of mesons propagating in a nucleus is studied with the help of a color-octet Pomeron partner present in the two-gluon model of the Pomeron. For a simple model with four meson-nucleon channels, color mixings are found to be absent for pointlike mesons and very small for small mesons. These results seem to validate the absorption model with two independent color components used in recent analyses of the nuclear absorption of J/ψJ/\psi mesons produced in nuclear reactions.Comment: 3 journal-style page

    Kinetic description of charmonium production in high-energy nuclear collisions

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    We study the evolution of charmonia as they collide with the constituents of the fireball produced in high-energy nucleus-nucleus collisions. The latter evolves in a manner controlled by the equation of state as given by lattice QCD, and is constructed in such a way that the observed hadronic spectra are correctly reproduced. A kinetic description of charmonium interactions with both quark-gluon and hadronic degrees of freedom allows to study in detail the evolution in different regimes, controlled by collision energy, kinematics and geometry. The data collected at the CERN-SPS accelerator are well described and new estimates for J/psi production at BNL-RHIC are presented.Comment: 19 pages, LaTeX, 13 .eps figure

    Charmonium Suppression by Comover Scattering in Pb+Pb Collisions

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    The first reports of ψ\psi and ψ\psi' production from experiment NA50 at the CERN SPS are compared to predictions based on a hadronic model of charmonium suppression. Data on centrality dependence and total cross sections are in good accord with these predictions.Comment: 9 pages, latex, 6 figures, epsf, figure added and text modified to clarify result

    Transverse energy distributions and J/ψJ/\psi production in Pb+Pb collisions

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    We have analyzed the latest NA50 data on transverse energy distributions and J/ψJ/\psi suppression in Pb+Pb collisions. The transverse energy distribution was analysed in the geometric model of AA collisions. In the geometric model, fluctuations in the number of NN collisions at fixed impact parameter are taken into account. Analysis suggests that in Pb+Pb collisions, individual NN collisions produces less , than in other AA collisions. The nucleons are more transparent in Pb+Pb collisions. The transverse energy dependence of the J/ψJ/\psi suppression was obtained following the model of Blaizot et al, where charmonium suppression is assumed to be 100% effective above a threshold density. With fluctuations in number of NN collisions taken into account, good fit to the data is obtained, with a single parameter, the threshold density.Comment: Revised version with better E_T fit. 4 pages, 2 figure

    Enhancement of gluonic dissociation of J/ψJ/\psi in viscous QGP

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    We have investigated the effect of viscosity on the gluonic dissociation of J/ψJ/\psi in an equilibrating plasma. Suppression of J/ψJ/\psi due to gluonic dissociation depend on the temperature and also on the chemical equilibration rate. In an equilibrating plasma, viscosity affects the temperature evolution and also the chemical equilibration rate, requiring both of them to evolve slowly compared to their ideal counter part. For Au+Au collisions at RHIC and LHC energies, gluonic dissociation of J/ψJ/\psi increases for a viscous plasma. Low PTP_T J/ψJ/\psi's are found to be more suppressed due to viscosity than the high PTP_T ones. Also the effect is more at LHC energy than at RHIC energy.Comment: 3 pages, 1 figur

    J/ΨJ/\Psi and Ψ\Psi ' Suppression in Heavy Ion Collisions

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    We study the combined effect of nuclear absorption and final state interaction with co-moving hadrons on the J/ΨJ/\Psi and Ψ\Psi ' suppression in proton-nucleus and nucleus-nucleus collisions. We show that reasonable description of the experimental data can be achieved with theoretically meaningful values of the cross-sections involved and without introducing any dicontinuity in the J/ΨJ/\Psi or Ψ\Psi ' survival probabilities.Comment: 10 pages, TeX, 2 Postscript figure

    J/Psi suppression in colliding nuclei: statistical model analysis

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    We consider the J/ΨJ/\Psi suppression at a high energy heavy ion collision. An ideal gas of massive hadrons in thermal and chemical equilibrium is formed in the central region. The finite-size gas expands longitudinally in accordance with Bjorken law. The transverse expansion in a form of the rarefaction wave is taken into account. We show that J/ΨJ/\Psi suppression in such an environment, when combined with the disintegration in nuclear matter, gives correct evaluation of NA38 and NA50 data in a broad range of initial energy densities.Comment: 14 pages, 13 figures. Accepted for publication in Phys. Rev.
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