6,172 research outputs found
In-Medium Effects on Charmonium Production in Heavy-Ion Collisions
Charmonium production in heavy-ion collisions is investigated within a
kinetic theory framework incorporating in-medium properties of open- and
hidden-charm states in line with recent QCD lattice calculations. A
continuously decreasing open-charm threshold across the phase boundary of
hadronic and quark-gluon matter is found to have important implications for the
equilibrium abundance of charmonium states. The survival of resonance
states above the transition temperature enables their recreation also in the
Quark-Gluon Plasma. Including effects of chemical and thermal off-equilibrium,
we compare our model results to available experimental data at CERN-SPS and
BNL-RHIC energies. In particular, earlier found discrepancies in the
ratio can be resolved.Comment: 4 pages RevTex including 4 eps-figures. v2: Minor modifications and
clarifications, typos corrected, Fig. 4 update
Medium Modifications of Charm and Charmonium in High-Energy Heavy-Ion Collisions
The production of charmonia in heavy-ion collisions is investigated within a
kinetic theory framework simultaneously accounting for dissociation and
regeneration processes in both quark-gluon plasma (QGP) and hadron-gas phases
of the reaction. In-medium modifications of open-charm states (c-quarks,
D-mesons) and the survival of J/psi mesons in the QGP are included as inferred
from lattice QCD. Pertinent consequences on equilibrium charmonium abundances
are evaluated and found to be especially relevant to explain the measured
centrality dependence of the psi'/psi ratio at SPS. Predictions for recent
In-In experiments, as well as comparisons to current Au-Au data from RHIC, are
provided.Comment: 4 Latex pages including 4 eps figures and IOP style files. Talk given
at the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus
Collisions, Quark Matter 2004, Oakland, CA USA, 11-17 Jan 2004. To appear in
J. Phys.
A Schematic Model For Density-Dependent Vector Meson Masses
A schematic two-level model consisting of a "collective" bosonic state and an
"elementary" meson is constructed that provides interpolation from a hadronic
description (a la Rapp/Wambach) to B/R scaling for the description of
properties of vector mesons in dense medium. The development is based on a
close analogy to the degenerate schematic model of Brown for giant resonances
in nuclei.Comment: 20 pages, latex with 8 figures: Talk given by GEB at AIP Klaus
Kinder-Geiger Memorial Meeting, 3 October 199
Quarkonia and Heavy-Quark Relaxation Times in the Quark-Gluon Plasma
A thermodynamic T-matrix approach for elastic 2-body interactions is employed
to calculate spectral functions of open and hidden heavy-quark systems in the
Quark-Gluon Plasma. This enables the evaluation of quarkonium bound-state
properties and heavy-quark diffusion on a common basis and thus to obtain
mutual constraints. The two-body interaction kernel is approximated within a
potential picture for spacelike momentum transfers. An effective
field-theoretical model combining color-Coulomb and confining terms is
implemented with relativistic corrections and for different color channels.
Four pertinent model parameters, characterizing the coupling strengths and
screening, are adjusted to reproduce the color-average heavy-quark free energy
as computed in thermal lattice QCD. The approach is tested against vacuum
spectroscopy in the open (D, B) and hidden (Psi and Upsilon) flavor sectors, as
well as in the high-energy limit of elastic perturbative QCD scattering.
Theoretical uncertainties in the static reduction scheme of the 4-dimensional
Bethe-Salpeter equation are elucidated. The quarkonium spectral functions are
used to calculate Euclidean correlators which are discussed in light of lattice
QCD results, while heavy-quark relaxation rates and diffusion coefficients are
extracted utilizing a Fokker-Planck equation.Comment: 33 pages, 28 figure
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