Unitary matrix models and phase transition

We study the unitary matrix model with a topological term. We call the topological term the theta term. In the symmetric model there is the phase transition between the strong and weak coupling regime at λc=2. If the Wilson term is bigger than the theta term, there is the strong-weak coupling phase transition at the same λc. On the other hand, if the theta term is bigger than the Wilson term, there is only the strong coupling regime. So the topological phase transition disappears in this case.