2.8 Deformations and Adding Flavour So far we have explored the AdS/CFT duality as it was first presented, basically as a mathematical construct. However the promise of describing a strongly coupled gauge theory in terms of a weakly coupled one was very exciting to students of QCD. Perhaps, it was thought, this would be a useful way to make calculations in the strongly coupled regime of QCD. However, there were some immediate obstacles to overcome: the CFT field theory present in the duality had many characteristics which makes it distinctly different to QCD. It is conformal, supersymmetric, strongly coupled in the UV, and has an infinite number of colours. In addition there aren’t any quarks. The addition of quarks is addressed in the next chapter. 44