Würzburg Seminar on Quantum Field Theory and Gravity

Anti-de-Sitter space as a rigid spacetime could be used as an infra-red cutoff for quantum field theories. It also allows interpolation between weak coupling and strong coupling, and phase transitions in the bulk manifest themselves as transitions between boundary conditions. I will discuss phase transitions in two dimensional solvable models and explain them using the boundary conformal theories. In doing this, a mechanism relevant for the quantum phase transition of the Yang-Mills theory in higher dimensions is conjectured.