Universal Flow in the First Stage of Relativistic Heavy Ion Collisions

TL;DR

This paper demonstrates that early collective flow in relativistic heavy ion collisions depends only on the tracelessness of the stress-energy tensor, regardless of matter composition or equilibration, simplifying early-stage modeling.

Contribution

It establishes that early flow is universal under the traceless stress-energy tensor condition, reducing uncertainties in collision modeling.

Findings

Early flow is independent of matter composition or equilibration.

Universality holds as long as the stress-energy tensor is traceless.

Simplifies modeling of initial collision stages.

Abstract

In the first moments of a relativistic heavy ion collision explosive collective flow begins to grow before the matter has yet equilibrated. Here it is found that as long as the stress-energy tensor is traceless, early flow is independent of whether the matter is composed of fields or particles, equilibrated or not, or whether the stress-energy tensor is isotropic. This eliminates much of the uncertainty in modeling early stages of a collision.