Constraining /s through high-p theory and data

We study whether it is possible to use high-p1 data/theory to constrain the temperature dependence of the shear viscosity over entropy density ratio il/s of the matter formed in ultrarelativistic heavy-ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC). We use two approaches: (i) We calculate high-p1 RAA and flow coefficients v2, v3, and v4 assuming different (il/s)(T ) of the fluid-dynamically evolving medium. (ii) We calculate the quenching strength (q/T 3) from our dynamical energy loss model and convert it to il/s as a function of temperature. It turned out that the first approach cannot distinguish between different (il/s)(T ) assumptions when the evolution is constrained to reproduce the low-p1 data. In distinction, (il/s)(T ) calculated using the second approach agrees surprisingly well with the (il/s)(T ) inferred through state-of-the-art Bayesian analyses of the low-p1 data even in the vicinity of Tc, while providing much smaller uncertainties at high temperatures.