The first seminar (Dmytro Volin, 27/02/2009) will be devoted to two-dimensional O(N) sigma models. We will discuss the Bethe Ansatz equations in the thermodynamical limit and show how to find the mass gap of the O(N) sigma models. In the second seminar (Benjamin Basso, 02/03/2009), we will explain how the previous considerations become relevant in the context of the AdS/CFT correspondence. We will argue indeed that the O(6) sigma model emerges as an effective description of the string dynamics in an appropriate limit. We will discuss the agreement of this picture with predictions coming from the gauge theory and based on the integrability of the planar dilatation operator.

IPhT