Understand
Recent hexadecapole (v4) and elliptic (v2) flow measurements are used to constrain estimates for the degree of local equilibrium, mean free path $\lambda$, and the viscosity to entropy density ratio (eta/s) of the plasma produced in Au+Au collisions at RootS = 200 GeV.
- The eccentricity-scaled flow coefficients v2/e2 and v4/e4 indicate that the plasma achieves a degree of local equilibrium within 5 - 10% of the value expected for a fluid with eta/s equal to the conjectured lower bound of 1/4pi.
- Estimates for $\lambda$ and eta/s as a function of collision centrality and particle transverse momentum pT, points to transverse expansion dynamics compatible with a strongly coupled low viscosity plasma.
Reading the bibliography…