Abstract
We investigate the symmetric linear model in two dimensions by means of an exact nonperturbative evolution equation. The perturbative infrared divergences are absent in this formulation. We use a simple approximative solution of the flow equation which corresponds to a derivative expansion for the effective action. For this gives a good picture of the Kosterlitz-Thouless phase transition.
- Received 11 October 1994
DOI:https://doi.org/10.1103/PhysRevLett.75.378
©1995 American Physical Society