Quantifying a Possibly Reduced Jet-Medium Coupling of the sQGP at the   LHC
  The nuclear modification factor R_{AA} measured in Pb+Pb collisions at the Large Hadron Collider (LHC) suggests that the jet-medium coupling in a Quark-Gluon Plasma at LHC energies is reduced as compared to energies reached at the Relativistic Heavy Ion Collider (RHIC). We estimate the reduction factor using a simple generic energy-loss model and find that the jet-medium coupling at the LHC is approximately 10% smaller than at RHIC. Moreover, we examine different jet-energy loss prescriptions with $dE/dx\sim E^a$ and show that the measured momentum dependence of the nuclear modification factor at the LHC rules out any model with $E^{a>1/3}$. 
Barbara Betz and Miklos Gyulassy
nucl-th hep-ph