The Equation of State and Viscosity in the Hydrodynamic Model

Abstract

The hydrodynamic model[1,2,3,4,5,6] has been influential in the development of the theory of high-energy heavy-ion collisions since its very beginning. One of the most important insights in the field was the discovery of collective flow through a comparison between experiment, the hydrodynamic and the cascade models. Two major components of collective flow have been unambigously observed so far: Transverse momentum transfer in the reaction plane — the Bounce-Off effect [7,8], and, only recently, the off-plane (perpendicular) Squeeze-Out, which was also predicted by nuclear fluid dynamics [4,9], has been demonstrated in a re-evaluation of old data [10,11].Since then microscopic models have learnt how to include collective effects in such treatments as the “quantum molecular dynamics” [12,13,14], and have become very successful in quantitative predictions. A present day evaluation of the hydrodynamic model must thus motivate the continued need for such simulations in comparison to the best microscopic models.KeywordsImpact ParameterNuclear MatterHydrodynamic ModelBulk ViscosityCollective FlowThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.