Extracting Bulk Properties of the Quark Gluon Plasma from Experiment

For the last quarter century, experiments at Brookhaven National Laboratory’s  Relativistic Heavy Ion Collider and the LHC at CERN have measured extremely high-energy heavy-ion collisions with the hope of producing the Quark Gluon Plasma (QGP) and extracting its properties. The success of this mission depends critically on combining careful, detailed and thorough measurement with complex multi-component theoretical simulations. I will first review how specific bulk properties are illuminated by specific experimental observables. I will then show how the comparison of these large heterogeneous data sets with computationally expensive models built on high-dimensional model-parameter spaces are rigorously constraining these properties through state-of-the-art Bayesian analysis. The extracted equation of state and chemical compositions are found to be consistent with lattice gauge theory. Other properties, which are not so well calculated on the lattice, such as the opacity and emissivity of QCD radiation, the diffusivity of both light and heavy quarks, and the viscosities have also been extracted. I will review where these determinations currently stand and how well they substantiate the claim of having produced the QGP in the laboratory.