Heavy quark flow as better probes of QGP properties

TL;DR

This study shows that heavy quark flow, especially charm quark v2, is more sensitive to the quark-gluon plasma's properties than light quark flow, challenging previous assumptions about the origin of v2.

Contribution

It reveals that charm quark v2 is more influenced by hydrodynamic flow than lighter quarks, highlighting heavy quark flow as a superior probe of QGP properties.

Findings

Charm v2 is more sensitive to hydrodynamic flow than light quark v2.

The escape mechanism's contribution to v2 decreases with quark mass.

Light quark collective flow is essential for charm quark v2.

Abstract

In earlier studies we have proposed that most parton $v_2$ comes from the anisotropic escape of partons, not from the hydrodynamic flow, even for semi-central Au+Au collisions at $\sqrt {s_{NN}}=200$ GeV. Here we study the flavor dependence of this escape mechanism with a multi-phase transport model. In contrast to naive expectations, we find that the charm $v_2$ is much more sensitive to the hydrodynamic flow than the lighter quark $v_2$, and the fraction of $v_2$ from the escape mechanism decreases strongly with the quark mass for large collision systems. We also find that the light quark collective flow is essential for the charm quark $v_2$. Our finding thus suggests that heavy quark flows are better probes of the quark-gluon-plasma properties than light quark flows.