Publication : t07/049
Centrality dependence of elliptic flow, the hydrodynamic limit, and the viscosity of hot QCD
Drescher H.-J. (Frankfurt Institute for Advanced Studies (FIAS), Johann Wolfgang Goethe-Universitat, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany)Dumitru A. (Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany)
Gombeaud C. (CEA, DSM, SPhT (Service de Physique Théorique), F-91191 Gif-sur-Yvette, FRANCE)
Ollitrault J.-Y. (CEA, DSM, SPhT (Service de Physique Théorique), F-91191 Gif-sur-Yvette, FRANCE)
Abstract:Année de publication : 2007
We show that the centrality and system-size dependence of elliptic flow measured at RHIC are fully described by a simple model based on eccentricity scaling and incomplete thermalization. We argue that the elliptic flow is at least 25% below the "hydrodynamic limit", even for the most central Au-Au collisions. This suggests that the viscosity to entropy density ratio is about twice as large as the lower bound conjectured from the AdS/CFT correspondence at infinite coupling but still much smaller than perturbative extrapolations. Perturbative gluon saturation in the wavefunctions of the colliding nuclei leads to a lower viscosity and a lower hydrodynamic limit of the eccentricity-scaled elliptic flow than standard Glauber initial conditions, and thus affects the extraction of the QCD equation of state from data.
Revue : Phys. Rev. C 76 024905 (2007)
DOI : 10.1103/PhysRevC.76.024905
Preprint : arXiv:0704.3553
PACS : 12.38.Mh, 24.85.+p, 25.75.Ld, 25.75.-q
Langue : Anglais
Fichier(s) à télécharger :
PhysRevC.76.024905.pdf 0704.3553v2.pdf
