of QCD. One such theory which astutely implements the spontaneous breaking of chiral $SU(N_f)\times
SU(N_f)$ symmetry was constructed by Sakai and Sugimoto [@SS]. The key idea in this approach is that the strongly-coupled and hence highly non-perturbative aspect of QCD in four dimensions in the limits $\lambda\equiv g^2_{YM}N_c\rightarrow \infty$ (“’t Hooft limit") and $N_c\rightarrow \infty$ (“large $N_c$ limit") can be approximated by a readily calculable weakly-coupled gravity solution in five dimensions. Since a dimensional reduction is involved, there is a Kaluza-Klein scale $M_{KK}$ that sets the energy scale of the effective theory. What results is a pure Yang-Mills theory in five dimensions dual to strongly-coupled QCD which when reduced to four dimensions can be cast in terms of an infinite tower of local vector fields coupled gauge invariantly to the pions. Thus as in the emergent case, the same type of hidden local symmetry (with an infinite tower of vector mesons and the pions) arises from top down. Remarkably this theory describes the meson sector [@SS] as well as the baryon sector [@HRYY-PRL; @HSSY] quite well.

Perhaps the most important outcome of the development is the appearance of baryons in the theory. The hidden local symmetry theory (with the infinite 