where m$_{q}$ is the quark mass matrix, and σ is the quark condensate matrix. Both are diagonal matrices. There are now four free parameters: z$_{m}$, m$_{q}$, σ, g$_{5}$ . g$_{5}$ can be fixed by operator product expansion for the product of currents, and we come to this a little later. We also take this opportunity to focus on just two flavours of quark, so in table 5.1, α, β = 1 , 2; a, b = 1 , 2 , 3; and t a = σ $^{a}$/ 2, where σ a are the Pauli matrices. This model with three flavours of quark have been investigated [114], and the results are good. Here though, the third flavour would provide an unnecessary complication. Models beyond three flavours would be futile because the lightest three quark flavours are of roughly the same mass and thus have an approximate SU(3) symmetry. The charm quark however is much heavier than the previous three quarks, and so the SU(4) symmetry is badly broken. As with the AdS/CFT correspondence, we claim that precise correspon- dence is obtained by equating the generating functional of the connected correlators in the four-dimensional theory with the effective action of the five-dimensional theory, with the UV boundary values of the 5D bulk fields set to the value of the sources in the 4D theory: 74 〈 Exp (∫ d $^{4}$xφ$_{0}$ ( x ) O ( x ) ) 〉 ∣ φ ( x, 0)= φ 0 ( x ) ∼ = Z 4 D (5.4)