Improving the application of Relativistic Fluid Dynamics to relativistic heavy-ion collisions is an ongoing challenge and currently a very active area of research: recent notable preprints on the topic are centered around two main themes:
- Formulation and implementation of viscous relativistic hydro, withemphasis on elliptic flow generation and application to RHIC. Here there are currently two groups to watch, the OSU group and the Stonybrook group: a careful study of these preprints reveals that there is still a considerable amount of discussion going on with regard to the viscous correction terms needed to be included in the calculation, the proper distribution functions to be used at freeze-out and the sensitivity of these calculations to other parameters e.g. the equation of state and the particulars of the phase transition. Nevertheless, the progress made in this area of research is quite impressive.
- Improving the description of freeze-out, in particular the separation of chemical and thermal freeze-out:
- An Approach to chemical freeze-out scenario of identified particle spectra at 200-AGeV Au-Au collisions at RHIC
One should note that the proper treatment of freeze-out and its splitting into an early chemical and later thermal freeze-out is most easily accomplished by the adoption of hybrid hydro+micro models, which are able to calculate freeze-out in a self-consistent and parameter free way (n.b. these approaches do have parameters to describe cross sections and resonance decays, but they are not used to control the freeze-out of the reaction).