Hydrodynamic description of heavy ion collisions

Abstract

Abstract. We give a short review of hydrodynamic models at heavy ion collisions from the point of view of initial conditions, an equation of states (EoS) and freezeout process. Then we show our latest results of a combined fully three-dimensional macroscopic/microscopic transport approach. In this model for the early, dense, deconfined stage relativistic 3D-hydrodynamics of the reaction and a microscopic nonequilibrium model for the later hadronic stage where the equilibrium assumptions are not valid anymore are employed. Within this approach we study the dynamics of hot, bulk QCD matter, which is being created in ultra-relativistic heavy ion collisions at RHIC. Hydrodynamic Models at RHICThe first five years of RHIC operations at √ s N N = 130 GeV and √ s N N = 200 GeV have yielded a vast amount of interesting and sometimes surprising results. There exists mounting evidence that RHIC has created a hot and dense state of deconfined QCD matter with properties similar to that of an ideal fluid [1, 2] -this state of matter has been termed the strongly interacting Quark-Gluon-Plasma (sQGP). One of the evidence is the success of ideal hydrodynamic models in various physical observables. Especially, for the first time, in elliptic flow the hydrodynamic limit shows good agreement with the experimental data at RHIC, though at AGS and SPS hydrodynamic models give larger value as compared to experimental data.The sophisticated 3D ideal hydrodynamic calculations, however, reveal that many of experimental data have not yet been fully evaluated or understood [5]. For example, elliptic flow at forward and backward rapidity ‡ and at peripheral collisions is overestimated by ideal hydrodynamical models. The Hanbury-Brown Twiss (HBT) puzzle is not completely understood from the point of view of hydrodynamics. These distinctions between hydrodynamic calculation and experimental data suggest that the ideal hydrodynamic picture is not applicable to all physical observables even in low transverse momentum region. At present our main interest in hydrodynamic models is the following: How perfect the sQGP is? ‡ Brazil group shows improved results of v 2 at forward/backward rapidity by using event-by-event fluctuated initial conditions [3].

Hydrodynamics and Flow

“…We show only results from ideal hydrodynamic models. One can also consult recent other reviews of hydrodynamic models at RHIC which complement the present lecture note [45,46,47,48,49,50,51,52]. We start by discussing some basic tests of whether the system produced in H.I.C.…”

Rapid hydrodynamic expansion in relativistic heavy-ion collisions

“…Relativistic hydrodynamics is very well suited for the description of the collective phase of the fireball expansion [14,16,25,26,27,28,29,30,31,32,33,34,35,36,37]. Assuming local thermal equilibration, perfect fluid hydrodynamics can be used.…”

Hydro-kinetic approach to relativistic heavy ion collisions

“…Hydrodynamic models successfully describe basic features of high energy nuclear collisions at CERN SPS and especially at BNL RHIC (for reviews see, e.g., Refs. [1,2,3]), where the utilization of ideal hydrodynamics was supported by theoretical results: it was advocated [4] that deconfined matter behaves like a perfect liquid. The hydrodynamic approach to A+A collisions implies a very hot and dense strongly interacting matter as the initial state.…”