147 Chapter 7: Conclusions and Outlook number of elastic energy loss approaches. Even more disturbing, none of these gives even a consistent qualitative agreement with data. In this thesis we confronted the two major areas of disagreement: the si- multaneous description of (1) intermediate- p$_{T}$ R$_{AA}$ and v$_{2}$ and (2) nonphotonic electron and light meson R$_{AA}$ . For the first we proposed a focusing mechanism that provides the necessary increase in v$_{2}$ and also decreases as a function of momenta. Future v$_{2}$ results, should they persist at such high percentages, would cast serious doubt on the applicability of perturbative methods to light mesons. On the other hand this might point to a medium geometry signifi- cantly different from our expectations, with radical consequences for hydrody- namics results. For the second we included both radiative and collisional energy loss pro- cesses with realistic geometrical modeling. This decreased the discrepancy between the presumed heavy quark and light quark and gluon energy loss as inferred from measurements at $_{Rhic}$. We also showed that this model is sensitive to changes in its input parameter, the density of scattering centers. However the significant α$_{s}$ dependence strongly suggests that the irreducible theoretical error will be large, which would reduce jets to mere qualitative probes of the medium. It is clear that future work in estimating the mag- nitude and possible minimization of major sources of theoretical error is of critical importance. Working under the assumption of jets as qualitative probe we looked for a qualitative test of energy loss mechanisms and found one in the momen-