Anisotropic hydrodynamics and the early-thermalization puzzle

TL;DR

This paper uses anisotropic hydrodynamics in 3+1 dimensions to study matter in heavy-ion collisions, showing that initial pressure anisotropy effects can be offset, making final observables insensitive to early thermalization details.

Contribution

It demonstrates that initial pressure anisotropy effects can be compensated, providing a potential solution to the early thermalization puzzle in heavy-ion collision modeling.

Findings

Final hadronic observables are insensitive to early-stage anisotropies.

Adjusting initial energy density can offset initial pressure anisotropy effects.

The model reproduces transverse-momentum spectra and flow observables.

Abstract

The framework of anisotropic hydrodynamics is used in 3+1 dimensions to analyze behavior of matter produced in ultra-relativistic heavy-ion collisions. The model predictions for the hadronic transverse-momentum spectra, directed and elliptic flows, and the HBT radii are presented. We show that the effects of the initial anisotropy of pressure may be compensated by appropriate adjustment of the initial energy density. In this way, the final hadronic observables become insensitive to the early stage dynamics and the early thermalization puzzle may be circumvented.