Hydrodynamic description of spectra at high transverse mass in ultrarelativistic heavy ion collisions

Abstract

Abstract. Transverse mass spectra of pions and protons measured in central collisions of heavy ions at the SPS and at RHIC are compared to a hydrodynamic parameterization. While the chemical temperature needed at RHIC is significantly higher compared to SPS, the spectra may be described using kinetic freeze-out parameters which are very similar for both beam energies. There is no necessity of much stronger transverse flow at RHIC. The contribution of such hydrodynamic emission at high transverse momenta is investigated in detail. It is shown that hydrodynamics may be relevant up to relatively high transverse momenta. The importance of the velocity profile used in this context is highlighted. Implications for the interpretation of elliptic flow are discussed.

Observable implications of geometrical and dynamical aspects of freeze-out in heavy ion collisions

“…The study reported in Ref. [30] shows that accounting for resonance feed-down leads to a temperature 30% higher and a transverse velocity 15% lower than in our study.…”

“…A similar generalization has been studied by Wiedemann [44]. Finally, in this paper, we explore the effects of a "hard-edge" versus a smooth spatial density profile; similar studies have recently been done by Tomásik et al [45] and Peitzmann [30] for the more restricted case of a transverselyisotropic source. This brings to eight the total number of parameters which we study.…”

Flow in ultra-relativistic heavy-ion collisions

“…An example of the very good description of the data provided by the Blast Wave is shown in figure 1. The Blast Wave parameterization used in these proceedings does not include resonance feed-down, which is an effect that must be present, but was found to have a minor effect on spectra [16]. The Blast Wave parameterization is also in agreement with the shift between the average emission points of pions and kaons and pions and protons measured by non-identical two-particle correlations [2].…”

Influence of hydrodynamics on the interpretation of the high pT hadron suppression at RHIC

“…(For reference the fit values for central collisions using the full fit are also given in Table 2.) Already in [16] it was argued that the hydrodynamic contribution to the hadron yield even beyond p T = 3 GeV/c is not negligible. This question can be revisited with the help of the refined fits performed here.…”

“…The present paper uses an extension of the hydrodynamical parameterization of [16], which includes effects of transverse flow and resonance decays. It was originally based on a computer program by Wiedemann and Heinz [20], which in turn builds upon [21].…”