Can the energy dependence of elliptic flow reveal the QGP phase transition?

Abstract

Ideal hydrodynamic simulations are performed to compute the evolution with collision energy of hadron spectra and elliptic flow between AGS and LHC energies. We argue that viscous effects should decrease with increasing energy, improving the applicability of ideal fluid dynamics at higher energies. We show that the increasing radial flow at higher energies pushes the elliptic flow to larger transverse momenta, leading to a peaking and subsequent decrease of the elliptic flow at fixed p_T with increasing collision energy, independent of whether or not there is a phase transition in the equation of state.Comment: Final version, to appear in the proceedings of Quark Matter 2009: 21th International Conference on Ultra-Relativistic Nucleus Nucleus Collisions (QM 2009), Knoxville, TN, Mar.30 - Apr.4, 2009. This version 2 uses larger fonts in Fig. 1c; no other change