Constraining the initial temperature and shear viscosity in a hybrid hydrodynamic model of $\sqrt{s_{NN}}$=200 GeV Au+Au collisions using pion spectra, elliptic flow, and femtoscopic radii

TL;DR

This paper introduces CHIMERA, a comprehensive framework for evaluating hydrodynamic models of heavy ion collisions, applying it to constrain initial temperature and shear viscosity using experimental data.

Contribution

The paper develops CHIMERA, integrating advanced features into hydrodynamic modeling, and applies it to extract physical parameters from experimental observables in heavy ion collisions.

Findings

Consistent description of pion spectra, elliptic flow, and femtoscopic radii.

Initial density profiles with pre-equilibrium flow fit data well.

Constraints on initial temperature and shear viscosity ratios.

Abstract

A new framework for evaluating hydrodynamic models of relativistic heavy ion collisions has been developed. This framework, a Comprehesive Heavy Ion Model Evaluation and Reporting Algorithm (CHIMERA) has been implemented by augmenting UVH 2+1D viscous hydrodynamic model with eccentricity fluctuations, pre-equilibrium flow, and the Ultra-relativistic Quantum Molecular Dynamic (UrQMD) hadronic cascade. A range of initial temperatures and shear viscosity to entropy ratios were evaluated for four initial profiles, $N_{part}$ and $N_{coll}$ scaling with and without pre-equilibrium flow. The model results were compared to pion spectra, elliptic flow, and femtoscopic radii from 200 GeV Au+Au collisions for the 0--20% centrality range.Two sets of initial density profiles, $N_{part}$ scaling with pre-equilibrium flow and $N_{coll}$ scaling without were shown to provide a consistent description of all three measurements.