0104041 - 1 Hydro+Cascade, Flow, the Equation of State,...

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1 Hydro+Cascade, Flow, the Equation of State, Predictions and Data D. Teaney a ,J .Jauret b , E.V. Shuryak a a Department of Physics and Astronomy, SUNY at Stonybrook, Stonybrook, NY 11794-3800 b Department of Chemistry, SUNY at Stonybrook, Stonybrook, NY 11794-3800 A Hydro+Cascade model has been used to describe radial and elliptic flow at the SPS and successfully predicted the radial and elliptic flow measured by the both STAR and PHENIX collaborations. Furthermore, a combined description of the radial and elliptic flow for different particle species, restricts the Equation of State(EoS) and points towards an EoS with a phase transition to the Quark Gluon Plasma(QGP). 1. Introduction Relativistic Hydrodynamics provides a link between the Equation of State(EoS) of the excited nuclear matter and collective observables such as elliptic flow( v 2 -s) and radial flow( T slope -s). At the SPS, pure hydrodynamics calculations can fit the transverse mass spectra for almost any EoS by choosing the freezeout temperature T f . However in non- central collisions, when v 2 was calculated for these same EoSs with the same T f -s, v 2 was above the data by a factor of two[1]. Bass and Dumitru[2] removed the T f inde- terminacy by injecting the particles into a microscopic transport model at a switching temperature T switch T c 165 MeV , and cascading the particles until they decoupled. With the freezeout parameter removed, the slope parameters for central PbPb collisions were calculated and found to agree with experimental values. The only parameter in this approach is the total multiplicity in the collision. Later, elliptic flow was calculated[3] in a similar Hydro+Cascade model and v 2 was only 20% above the data. Since at freezeout the viscosity is certainly important, it was not surprising that the introduction of a cascade reduced the elliptic flow. It surprising that Hydro+Cascade could simultaneously reproduce the elliptic and radial flow for different particle species as a function of impact parameter. Furthermore, the combined analysis of radial and elliptic flow restricted possible EoSs since the freezeout temperature could no longer be adjusted to make any EoS fit any slope parameter. Roughly speaking,
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0104041 - 1 Hydro+Cascade, Flow, the Equation of State,...

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