Has the QCD Critical Point been Signaled by Observations at RHIC ?

Lacey, Roy A.; Ajitanand, N. N.; Alexander, J. M.; Chung, P.; Holzmann, W. G.; Issah, M.; Taranenko, A.; Danielewicz, P.; Stocker, Horst

Has the QCD Critical Point been Signaled by Observations at RHIC ?

Authors

Description

The shear viscosity to entropy ratio ($η/s$) is estimated for the hot and dense QCD matter created in Au+Au collisions at RHIC ($\sqrt{s_{NN}}=200$ GeV). A very low value is found $η/s \sim 0.1$, which is close to the conjectured lower bound ($1/4π$). It is argued that such a low value is indicative of thermodynamic trajectories for the decaying matter which lie close to the QCD critical end point.
4 pages, 3 figures. Revised version, accepted for publication in PRL