Hydrodynamics of transversally thermalized partons in ultra-relativistic heavy-ion collisions

TL;DR

This paper develops a hydrodynamic model for transversally thermalized matter in ultra-relativistic heavy-ion collisions, explaining how energy conversion in transverse clusters leads to observable radial and elliptic flows.

Contribution

It introduces a thermodynamically consistent 2D hydrodynamic formalism based on transverse clusters, providing a novel description of early-stage collision dynamics.

Findings

Model reproduces experimental radial flow data

Clusters do not perform work longitudinally

Strong radial and elliptic flows are generated

Abstract

The hydrodynamic description of transversally thermalized matter, possibly formed at the early stages of ultra-relativistic heavy-ion collisions, is developed. The formalism is based on the thermodynamically consistent approach with all thermodynamic variables referring to two-dimensional objects, the so-called transverse clusters, which are identified with the particles having the same rapidity. The resulting hydrodynamic equations for a single cluster have the form of the two-dimensional hydrodynamic equations of the perfect fluid. Since the clusters do not perform any work in the longitudinal direction, their energy is completely transformed and used to generate strong radial and elliptic flows that turn out to be compatible with the experimental data.