Holographic Descriptions Of QCD

In this thesis we investigate proposed duals to QCD. Duals to QCD fall into two categories: top-down' and bottom-up’. We take inspiration from both by truncating a consistent solution to the type IIB supergravity equations of motion (top-down). This model demonstrates dynamical chiral symmetry breaking, has a running coupling and contains a holographic description of the vector meson sector. By artificially extending the existing U(1) symmetry to SU(2) (bottom-up) we then obtain a holographic description of the axial vector sector. We show that this model reproduces the masses and decay constants of the lightest mesons to the 10% level. By regulating the UV with a sharp cut-off we can reproduce the rho meson masses to within 2%. Finally we demonstrate that this model can be used to reproduce a very good agreement with hadronization data for particle production over a range of four orders of magnitude.