Elliptic flow at RHIC: Where and when was it formed?

Abstract

Evolution of the elliptic flow of hadrons in heavy-ion collisions at RHIC energies is studied within the microscopic quark–gluon string model. The elliptic flow is shown to have a multi-component structure caused by (i) rescattering and (ii) absorption processes in spatially asymmetric medium. Together with different freeze-out dynamics of mesons and baryons, these processes lead to the following trend in the flow formation: the later the mesons are frozen, the weaker their elliptic flow, whereas baryon fraction develops stronger elliptic flow during the late stages of the fireball evolution. The phase-space distributions of the emitted particles are studied as well. The flow is shown to be formed both in the central and in the fragmentation regions of the reaction. Comparison with the PHOBOS data demonstrates the model ability to reproduce the v2ch(η) signal in different centrality bins.