Relativistic Heavy Ion Collisions: Viscous Hydrodynamic Simulations and Final State Interactions

TL;DR

This dissertation advances the understanding of relativistic heavy ion collisions by extending ideal hydrodynamic models to include viscosity and final state interactions, providing predictions for LHC energies and analyzing their impact on flow observables.

Contribution

It introduces viscous hydrodynamic simulations based on second order relativistic equations and investigates final state interactions, enhancing the modeling of heavy ion collision outcomes.

Findings

Viscous hydrodynamics constrains eta/s ratio consistent with experimental data.

Predicted elliptic flow v_2 at LHC energies is 10% higher than at RHIC.

Final state interactions can modify v_2 by approximately 20%.

Abstract

In this dissertation I introduce relativistic heavy ion collisions and describe theoretical approaches to understanding them--in particular, viscous hydrodynamic simulations and investigations of final state interactions. The successful ideal hydrodynamic models of the collisions at the Relativistic Heavy Ion Collider (RHIC) were extended by performing viscous hydrodynamic simulations. This was done by making use of the recently derived full conformally invariant second order relativistic viscous hydrodynamic equations. Results for multiplicity, radial flow and elliptic flow in sqrt{s_NN}=200 GeV Au+Au RHIC collisions are presented and the range of the ratio of shear viscosity over entropy density eta/s for which our hydrodynamic model is consistent with experimental data is quoted. In addition, simulations were performed of the planned sqrt{s_NN}=5.5 TeV Pb+Pb and sqrt{s}=14 TeV p+p collisions at the Large Hadron Collider (LHC). The elliptic flow coefficient v_2 is predicted to be 10% larger for the Pb+Pb collisions compared to top energy RHIC collisions, and is predicted to be consistent with zero for proton collisions unless eta/s < 0.08. Finally, final state interactions were investigated within the distorted wave emission function (DWEF) model. Work is presented on an improved understanding of the DWEF model, and the potential effect of final state interactions in the form of a pion optical potential on the elliptic flow coefficient v_2 was calculated to be at the ~20% level.