Universal Flow in the First fm/c at RHIC

TL;DR

This paper demonstrates that the initial flow patterns at RHIC are largely independent of the matter's state, depending mainly on the initial energy density, which simplifies the setup of hydrodynamic models.

Contribution

It shows that initial flow in heavy-ion collisions can be universally described by energy density profiles, reducing uncertainties in hydrodynamic initializations.

Findings

Elliptic and radial flow depend primarily on initial energy density.

Different theoretical descriptions yield similar collective velocities.

Simplifies initial condition assumptions for hydrodynamic models.

Abstract

We will show how both elliptic and radial flow generated during the first fm/c at RHIC can be expressed in a form which is quasi-independent of the state of matter and depends only on the initial energy density profile. Descriptions based on partons or classical fields, thermalized or highly anisotropic, all lead to the same collective velocity given a few easily satisfied conditions. This significantly narrows the uncertainty for initializing hydrodynamic prescriptions.