A comparison of holographic toy models for QCD

Abstract

The AdS/CFT correspondence and its generalization, gauge/gravity duality, is a holographic duality relation equating a gravitational theory in a bulk background geometry with a field theory at the boundary of the geometry. Duality means that if the gravitational theory is weakly coupled, thus calculable, the field theory is nonperturbative. The first correspondence, for $AdS_5\times S^5$ vs. ${\cal N}=4$ SYM, and most other examples, are supersymmetric, and come from string theory, from a system of branes in a decoupling limit. But since the original goal of the AdS/CFT program is to find a way to calculate nonperturbative QCD quantities, besides supersymmetric string models, also some phenomenological (or semi-phenomenological) models were proposed. Nevertheless, as of now, no exact holographic model of QCD was found. In this thesis we propose to compare the most relevant (toy) models, focusing on the calculation of some mass spectra. (AU)