cutoff, and no dynamical determination of the quark mass and condensate. We took the Constable-Myers geometry of chapter 4 and truncated it by removing the S 5 part of the spacetime. This then provided a model which was everywhere smooth, and had all the features that we analysed in chapter 4: confinement, a mass gap, and spontaneous breaking of chiral symmetry. The model, like QCD, only depended on two parameters: the light quark mass m$_{q}$ , and the strong coupling scale Λ (c.f. the model of chapter 5 which had three parameters). For comparison with chapter 5, we calculated the same quantities and found agreement with experiment to the 10% level. 

Whilst chapter 6 had regularized the IR of AdS-QCD models, chapter 7 dealt with regularizing the UV of such models. Without regularization in the UV, we were implicitly trying to solve a string theory in the strongly coupled regime. The simplest approach was to include a hard UV cutoff in the gravity dual. This removed the strongly coupled regime from the theory, and made predictions of the vector meson spectrum to within 2% of accepted values. However, the UV cutoff complicated the operator-field matching process. Firstly if a field had an anomalous dimension it would have to be fitted to a different operator with the relevant dimension, and secondly irrelevant operators would become more and more dominant as we neared the non-perturbative regime. Hence they would have to be encoded in the gravity dual. Without being able to address each complication fully we instead looked at an example of each and found that, for these particular examples, the effect was not large. 

The final chapter addressed hadronization. We postulated that after some annihilation event in a particle accelerator, the residual energy took on the shape of a Gaussian. The initial multiplicities of some hadron species would then be given by the overlap between this Gaussian and the radial function which represented that particular hadron in the QCD holographic 

