Charmonium suppression from purely geometrical effects

  • The extend to which geometrical effects contribute to the production and suppression of the J/psi and qq minijet pairs in general is investigated for high energy heavy ion collisions at SPS, RHIC and LHC energies. For the energy range under investigation, the geometrical e ects referred to are shadowing and anti-shadowing, respectively. Due to those effects, the parton distributions in nuclei deviate from the naive extrapolation from the free nucleon result; fA 6= AfN. The strength of the shadowing/anti-shadowing e ect increases with the mass number. Therefore it is interesting to see the di erence between cross sections for e.g. S+U vs. Pb+Pb at SPS. The recent NA50 results for the survival probability of produced J/psi s has attracted great attention and are often interpreted as a signature of a quark gluon plasma. This publication will present a fresh look on hard QCD e ects for the charmonium production level. It is shown that the apparent suppression of J/psi s must also be linked to the production process. Due to the uncertainty in the shadowing of gluons the suppression of charmonium states might not give reli- able information on a created plasma phase at the collider energies soon available. The consequences of shadowing e ects for the xF distribution of J/psi s at s = 20 GeV, s = 200 GeV and s = 6 TeV are calculated for some relevant combinations of nuclei, as well as the pT distribution of minijets at midrapidity for Nf = 4 in the final state.

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Author:Nils HammonGND, Lars GerlandGND, Horst StöckerORCiDGND, Walter GreinerGND
Document Type:Preprint
Date of Publication (online):2005/12/12
Year of first Publication:1998
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2005/12/12
Tag:Kollisionen schwerer Ionen; QCD; Quanten-Chromodynamik; Strahl
QCD; Quantum Chromodynamic; heavy ion collisions; jet
Source:Phys.Rev.C59:2744-2752,1999., revised version 2): Wed, 28 Oct 1998
Institutes:Physik / Physik
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):License LogoDeutsches Urheberrecht