HAL : in2p3-00193294, version 1
 arXiv : 0711.3917
 Physical Review C 77 (2008) 024912
 Cold Nuclear Matter Effects on $J/\Psi$ production as Constrained by Deuteron-Gold Measurements at $\sqrt{s_{NN}}$ = 200 GeV
 PHENIX Collaboration(s)
 (2008)
 We present a new analysis of J/psi production yields in deuteron-gold collisions at sqrt(s_NN) = 200 GeV using data taken by the PHENIX experiment in 2003 and previously published in [S.S. Adler et al., Phys. Rev. Lett 96, 012304 (2006)]. The high statistics proton-proton J/psi data taken in 2005 is used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors R_dAu. A suppression of J/psi in cold nuclear matter is observed as one goes forward in rapidity (in the deuteron-going direction), corresponding to a region more sensitive to initial state low-x gluons in the gold nucleus. The measured nuclear modification factors are compared to theoretical calculations of nuclear shadowing to which a J/psi (or precursor) break-up cross-section is added. Breakup cross sections of sigma_breakup = 2.8^[+1.7_-1.4] (2.2^[+1.6_-1.5]) mb are obtained by fitting these calculations to the data using two different models of nuclear shadowing. These breakup cross section values are consistent within large uncertainties with the 4.2 +/- 0.5 mb determined at lower collision energies. Projecting this range of cold nuclear matter effects to copper-copper and gold-gold collisions reveals that the current constraints are not sufficient to firmly quantify the additional hot nuclear matter effect.
 Thème(s) : Physique/Physique Nucléaire Expérimentale
 Lien vers le texte intégral : http://fr.arXiv.org/abs/0711.3917
 in2p3-00193294, version 1 http://hal.in2p3.fr/in2p3-00193294 oai:hal.in2p3.fr:in2p3-00193294 Contributeur : Suzanne Robert <> Soumis le : Lundi 3 Décembre 2007, 11:32:10 Dernière modification le : Lundi 3 Mars 2008, 10:26:09