Development of transverse flow at small and large opacities in conformal kinetic theory

TL;DR

This paper investigates how transverse flow develops in different collision systems using kinetic theory, revealing persistent deviations from hydrodynamics even at high opacities due to pre-equilibrium effects.

Contribution

It combines analytical and numerical methods within conformal kinetic theory to describe transverse flow across a range of opacities, highlighting deviations from hydrodynamics at large opacities.

Findings

Transverse flow develops continuously from small to large opacities.

Deviations from hydrodynamics persist even at high opacities.

Pre-equilibrium phase significantly influences flow development.

Abstract

We employ an effective kinetic description, based on the Boltzmann equation in the relaxation time approximation, to study the space-time dynamics and development of transverse flow of small and large collision systems. By combining analytical insights in the small opacity limit with numerical simulations at larger opacities, we are able to describe the development of transverse flow from very small to very large opacities. Suprisingly, we find that deviations between kinetic theory and hydrodynamics persist even in the limit of very large opacities, which can be attributed to the presence of the early pre-equilibrium phase.