Extracting the jet transport coefficient from jet quenching in high-energy heavy-ion collisions

Within five different approaches to parton propagation and energy loss in dense matter, a phenomenological study of experimental data on suppression of large-${p}_{T}$ single inclusive hadrons in heavy-ion collisions at both the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) was carried out. The evolution of bulk medium used in the study for parton propagation was given by 2 + 1 dimensional or 3 + 1 dimensional hydrodynamic models which are also constrained by experimental data on bulk hadron spectra. Values for the jet transport parameter $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{q}$ at the center of the most central heavy-ion collisions are extracted or calculated within each model, with parameters for the medium properties that are constrained by experimental data on the hadron suppression factor ${R}_{AA}$. For a quark with initial energy of 10 GeV we find that $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{q}\ensuremath{\approx}1.2\ifmmode\pm\else\textpm\fi{}0.3$ GeV${}^{2}$/fm at an initial time ${\ensuremath{\tau}}_{0}=0.6$ fm/$c$ in Au + Au collisions at $\sqrt{s}=200$ GeV/n and $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{q}\ensuremath{\approx}1.9\ifmmode\pm\else\textpm\fi{}0.7$ GeV${}^{2}$/fm in Pb + Pb collisions at $\sqrt{s}=2.76$ TeV/n. Compared to earlier studies, these represent significant convergence on values of the extracted jet transport parameter due to new constraints provided by recent experiment data from the LHC.