Divergence-type 2+1 dissipative hydrodynamics applied to heavy-ion collisions

TL;DR

This paper applies divergence-type dissipative hydrodynamics to model the evolution of the quark-gluon plasma in heavy-ion collisions, highlighting differences from second-order theories and implications for extracting viscosity.

Contribution

It demonstrates the application of divergence-type theory to 2+1D heavy-ion collision hydrodynamics, going beyond second-order theories and comparing results with experimental data.

Findings

DTT predicts lower $p_T$ for maximum elliptic flow.

DTT allows for higher $ta/s$ than second-order theories.

Differences between hydrodynamic formalisms affect viscosity extraction.

Abstract

We apply divergence-type theory (DTT) dissipative hydrodynamics to study the 2+1 space-time evolution of the fireball created in Au+Au relativistic heavy-ion collisions at $\sqrt{s_{NN}}=$200 GeV. DTTs are exact hydrodynamic theories that do no rely on velocity gradient expansions and therefore go beyond second-order theories. We numerically solve the equations of motion of the DTT for Glauber initial conditions and compare the results with those of second-order theory based on conformal invariants (BRSS) and with data. We find that the charged-hadron minumum-bias elliptic flow reaches its maximum value at lower $p_T$ in the DTT, and that the DTT allows for a value of $\eta/s$ slightly larger than that of the BRSS. Our results show that the differences between viscous hydrodynamic formalisms are a significant source of uncertainty in the precise extraction of $\eta/s$ from experiments.