List of Tables 1.1 The five consistent types of superstring theory . . . . . . . . 28 3.1 Choice of D3 and D7 embedding. Filled directions are marked with a cross. Unfilled directions by a dot. . . . . . . . . . . . 46 4.1 0 ++ glueball masses from Constable Myers geometry. Nor- malization is such that the ground state mass is set to one (arbitrary units). . . . . . . . . . . . . . . . . . . . . . . . . 64 4.2 Choice of D3 and D7 embedding. Filled directions are marked with a cross. Unfilled directions by a dot. . . . . . . . . . . . 66 4.3 Vector meson spectrum comparing CM and pure AdS back- grounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 5.1 Operators/fields of the model of [2] . . . . . . . . . . . . . . 73 5.2 Results of model from [2] for QCD observables. m$_{q}$ = 2 . 3MeV, σ = (327MeV) $^{3}$, z$_{m}$ = 323(MeV) − 1 . . . . . . . . . . . . . . 80 6.1 Comparing the best fit results in [2] and the model presented here . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 7.1 Preferred values for: a) the quantum dimension ω of the operator ¯ qγ $^{µ}$q (left), and b) the field dual to G Tr F 4 (right) 104 8.1 Mean multiplicities for a typical e $^{+}$e − collision at √$_{s}$ = 91 . 2 GeV [3] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 8.2 Results of the model for hadron yields at √$_{s}$ = 91 . 2 GeV (centre column) and √$_{s}$ ∼ 30 GeV (right column). The relevant 3+1 free parameter values are shown in the final row. 118 vii