  We compare calculations of jet quenching observables at sqrt s = 2.76 ATeV to
preliminary LHC data from weak-coupling pQCD and strong-coupling AdS/CFT drag
energy loss models. Rigorously constrained to sqrt s = 200 AGeV RHIC pi^0
suppression data and introducing no free parameters, the pQCD-based WHDG model
simultaneously describes qualitatively the suppression of light hadrons and
quantitatively the azimuthal anisotropy (over many centrality classes) of light
hadrons and the suppression of D mesons at LHC. The drag predictions shown
here--qualitatively constrained to RHIC data--compare poorly to the measured
suppression of D mesons, but the current experimental uncertainties are large.
The double ratio of D to B meson R_AA(p_T) should provide a robust experimental
measurement to distinguish between the very different assumptions of the
strength of interactions in the QGP produced in heavy ion collisions; i.e.,
whether, from a jet quenching standpoint, the medium is either weakly- or
strongly-coupled.
