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

TL;DR

This paper proposes a method to accurately determine the shear viscosity to entropy density ratio of the quark-gluon plasma from ultra-central heavy-ion collision data, emphasizing uncertainty quantification.

Contribution

It introduces a novel approach focusing on ultra-central collisions and systematic uncertainty analysis to improve eta/s extraction accuracy.

Findings

Uncertainty is minimized in ultra-central collisions.

A global fit to azimuthal harmonic data yields the most precise eta/s.

Preliminary results demonstrate the method's potential.

Abstract

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. Only after a comprehensive and systematic accounting of all sources of uncertainty can a reliable measurement be claimed. In these proceedings we report preliminary results; full and final results will be presented in a separate publication.