Investigating the collision energy dependence of e/s in the beam energy scan at the BNL Relativistic Heavy Ion Collider using Bayesian statistics
We determine the probability distributions of the shear viscosity over the entropy density ratio e/s in the quark gluon plasma formed in Au Au collisions at sNN=19.6,39, and 62.4GeV, using Bayesian inference and Gaussian process emulators for a model to data statistical analysis that probes the full input parameter space of a transport viscous hydrodynamics hybrid model. We find the most likely value of e/s to be larger at smaller sNN, although the uncertainties still allow for a constant value between 0.10 and 0.15 for the investigated collision energy range.