Extracting the shear viscosity of the quark-gluon plasma from flow in ultra-central heavy-ion collisions

Understand

We propose a method for extracting the shear viscosity over entropy density ratio (eta/s) of the quark-gluon plasma from experimental data.

• We argue that uncertainty due to poor knowledge of the earliest stages of a heavy-ion collision is smallest for ultra-central events.
• The most precise value of eta/s can thus be obtained from a global fit to p_T-integrated Fourier harmonics of azimuthal correlations.
• We further outline a method for quantifying the overall uncertainty in the extracted value.