Time evolution of the anisotropies of the hydrodynamically expanding sQGP

TL;DR

This paper investigates how the anisotropies in the quark-gluon plasma created in high-energy collisions evolve over time, focusing on the effects of sound speed and viscosity using hydrodynamic simulations.

Contribution

It provides a detailed numerical analysis of the time evolution of anisotropies in sQGP, highlighting the roles of sound speed and viscosity in this process.

Findings

Anisotropies evolve significantly during hydrodynamic expansion.

Sound speed and viscosity critically influence anisotropy evolution.

Results help interpret experimental measurements of momentum anisotropies.

Abstract

In high energy heavy ion collisions of RHIC and LHC, a strongly interacting quark gluon plasma (sQGP) is created. This medium undergoes a hydrodynamic evolution, before it freezes out to form a hadronic matter. The initial state of the sQGP is determined by the initial distribution of the participating nucleons and their interactions. Due to the finite number of nucleons, the initial distribution fluctuates on an event-by-event basis. The transverse plane anisotropy of the initial state can be translated into a series of anisotropy coefficients or eccentricities: second, third, fourth-order anisotropy etc. These anisotropies then evolve in time, and result in measurable momentum-space anisotropies, to be measured with respect to their respective symmetry planes. In this paper we investigate the time evolution of the anisotropies. With a numerical hydrodynamic code, we analyze how the speed of sound and viscosity influence this evolution.