The radial flow, equation of state and freeze-out phenomena

This is a status report on the on-going work [1] aiming at producing new hydro-based event generator HKM (the hydro-kinetic model) which incorporates such features as EOS with the QCD phase transition. We discuss whether data on radial flow can help us to restrict EOS. We argue that the usual fixed-T freeze-out condition is too crude and a more sophisticated one is needed: the “local” one is studied in details. Comparison with RQMD shows that the results for heavy ions agree well, while for medium one hydro overpredicts flow. Both RQMD and HKM reproduce magnitude of radial flow at SPS, but need additional repulsion between baryons (relative to resonance gas [13]) to reproduce it at AGS. New ideas related with event-per-event fluctuations are discussed, which can help better measure matter properties at the freeze-out.