4.7 As in Fig. 4.6 but for light u, d quarks and gluons. The yellow bands are computed in this case with effective g, u path lengths L$_{g}$ = 4 . 0 and L$_{u}$ = 5 . 0 fm based on Eq. (4.7). Note that charm and light quark quenching are similar in this p$_{T}$ range. . . . . 106 4.8 The consistency of the extended jet quenching theory is tested by comparing its prediction to the nuclear modification of the π 0 spectra observed by Phenix [368–370]. . . . . . . . . . . . 108 4.9 Model sensitivity to varying dN$_{g}$/dy , which is much greater than observed in [306]. The susceptibility to changes in the fixed α$_{s}$ suggests the need to investigate the theoretical error stemming from the coupling. . . . . . . . . . . . . . . . . . . . . . . . . 111 4.10 The ratio of rms width, σ ( L ), to the mean fractional energy loss 〈 ϵ 〉 for radiative, elastic and convoluted energy loss dis- tributions is shown as a function of the path length, L , for a Bjorken expanding plasma with dN$_{g}$/dy = 1000. The case of an up quark jet with E = 15 GeV is shown. Notice that the elas- tic distribution is significantly narrower than the radiative one. This amplifies the effect of elastic energy loss on R$_{AA}$ relative to radiative. . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 xv