Footprints of the (Nearly) Perfect Liquid

TL;DR

This paper investigates flow observables in relativistic heavy-ion collisions to extract information about the nearly perfect liquid's properties, including viscosity and scaling behaviors, across various conditions and system sizes.

Contribution

It provides new insights into the ideal hydrodynamic limit, estimates the shear viscosity to entropy ratio, and tests scaling laws in different collision regimes.

Findings

Evidence supporting the near-ideal fluid behavior

Estimated $ ext{η/s}$ close to the conjectured lower bound

Validation of constituent quark scaling at low energy

Abstract

In relativistic heavy-ion collisions, the system has gone through a series of evolution, almost at every stage of its evolution it leaves behind footprints in flow observable. Those footprints contain valuable information of the bulk property of the (nearly) perfect liquid. By examing footprints of the nearly perfect liquid, we address a few important issues, including the ideal hydrodynamic limit, estimation of $\eta/s$, testing the Number of Constituent Quark scaling at low energy, in small system, at large transverse momentum, and in forward region. Future prospect of flow study is discussed.