113 Chapter 4: Fluctuations in Jet Tomography Figure 4.10: The ratio of rms width, σ ( L ) , to the mean fractional energy loss 〈 ϵ 〉 for radiative, elastic and convoluted energy loss distributions 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 elastic distribution is significantly narrower than the radiative one. This amplifies the effect of elastic energy loss on R$_{AA}$ relative to radiative. [400, 401], for the Lhc leads to small energy losses at high momenta that can be well approximated by the pocket asymptotic energy loss formulae see Fig. 4.11. As p$_{T}$ increases the log( E ) /E reduction in energy loss is not compensated by the slow (in comparison to $_{Rhic}$) increase in the power law ϵ$_{rad}$ = Δ E$_{rad}$/E ∼ α 3 s log( E/µ $^{2}$L ) /E (4.9) ϵ$_{el}$ = Δ E$_{el}$/E ∼ α 2 s log( √ ET/m$_{g}$ ) /E ; (4.10)