2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/189833The 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 PRLNuclear Experimenttext