D. Everett, Wei-Yao Ke, et al. (JETSCAPE Collaboration), Phenomenological Constraints on the Transport Properties of QCD Matter with Data-Driven Model Averaging, Phys. Rev. Lett. 126, 242301, 2021

Using combined data from the Relativistic Heavy Ion and Large Hadron Colliders, we constrain the temperature-dependent shear and bulk viscosities of quark-gluon plasma (QGP) at temperatures of ∼150–350 MeV. We use Bayesian inference to translate experimental and theoretical uncertainties into probabilistic constraints for the viscosities. With Bayesian model averaging we estimate uncertainties rising from different model assumptions on the transition from hydrodynamics to hadron transport in the plasma’s final evolution stage for the first time, providing the most reliable phenomenological constraints to date on the QGP viscosities.

Figure: 90% credible intervals for the priors (gray) and Bayesian model averaged posteriors for the specific bulk (left) and shear (right) viscosities, along with their corresponding information gain (Kullback-Leibler divergence DKL).

Theory group’s Wei-Yao Ke made a significant contribution to this analysis. The JETSCAPE collaboration includes a number of Berkeley scientists: B. Jacak, P. Jacobs, W.Y. Ke, J. Mulligan, D. Oliinychenko, X.N. Wang.