Shear Viscosity to Entropy Density Ratio of Quark Gluon Plasma at Finite Baryon Densities

The Quark Gluon Plasma, which is measured experimentally in relativistic heavy ion collisions, behaves as a near perfect fluid where the shear viscosity to entropy density (η/s) ratio approaches zero. Relativistic viscous hydrodynamic calculations have been extremely successful in describing the flow of the Quark Gluon Plasma, thus, confirming the nearly perfect fluid paradigm at zero baryon density. Current experiments at the Relativistic Heavy Ion Collider (RHIC) are now probing finite baryon densities where the η/s of the Quark Gluon Plasma remains unknown. In this study, we use the Hadron Resonance Gas (HRG) model to calculate η/s at low temperatures (between T=100-155 MeV) and at finite baryon densities. We use the most state-of-the-art Particle Data Group list (PDG16+) and incorporate interactions by comparing excluded volume corrections and repulsive mean field calculations. We find a suppression of η/s at large baryon densities, which would be expected in the absence of a critical point.