5.2 R c $_{AA}$( p$_{T}$ ) and R b $_{AA}$( p$_{T}$ ) predicted for central Pb + Pb at Lhc comparing AdS/CFT Eq. (5.1) and pQCD using the WHDG model [152] convolving elastic and inelastic parton energy loss. Possible initial gluon rapidity densities at Lhc are given by dN$_{g}$/dy = 1750, from a Phobos [87, 403] extrapolation, or dN$_{g}$/dy = 2900, from the KLN model of the color glass con- densate (CGC) [400]. The top two curves from pQCD increase with p$_{T}$ while the bottom two curves from AdS/CFT slowly decrease with p$_{T}$ . The AdS/CFT parameters here were found using the “obvious” prescription with α$_{SY M}$ = . 05, τ$_{0}$ = 1 fm/c, giving D = 3 / 2 πT (abbreviated to D = 3 in the figure). Simi- lar trends were seen for the other input parameter possibilities discussed in the text. The “(” and “]” denote momenta after which possible string theoretic corrections may need to be con- sidered; the curves’ increasing transparency from “(” to “]” is meant to additionally emphasize this, see text. . . . . . . . . 127 xviii