Hans-Joachim Drescher, Adrian Dumitru, Clement Gombeaud, Jean-Yves Ollitrault
Published 2007-04-26, updated 2007-06-28Version 2
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 (ideal) ``hydrodynamic limit'', even for the most central Au-Au collisions. This lack of perfect equilibration allows for estimates of the effective parton cross section in the Quark-Gluon Plasma and of its viscosity to entropy density ratio. We also show how the initial conditions affect the transport coefficients and thermodynamic quantities extracted from the data, in particular the viscosity and the speed of sound.
Comments: 5 pages, 2 figures. Extended discussion of the results, in particular of lower viscosity and sound velocity required by CGC initial conditions
Journal: Phys.Rev.C76:024905,2007
The physics of the centrality dependence of elliptic flow
Is the centrality dependence of the elliptic flow $v_2$ and of the average $<p_T>$ in RHIC experiments more than a Core-Corona Effect?
Saturation of Elliptic Flow and the Transport Opacity of the Gluon Plasma at RHIC
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