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

TL;DR

This paper uses ideal hydrodynamic simulations to study how elliptic flow varies with collision energy, suggesting that radial flow effects can obscure signals of the QGP phase transition.

Contribution

It demonstrates that radial flow influences elliptic flow at different energies, challenging the idea that elliptic flow alone signals the QGP phase transition.

Findings

Elliptic flow peaks and then decreases at fixed p_T with increasing energy.

Viscous effects diminish at higher energies, making ideal hydrodynamics more applicable.

Radial flow effects can mask the QGP phase transition signature.

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.