High Precision Verification of the Kosterlitz Thouless Scenario
  We verify the Kosterlitz Thouless scenario for three different SOS (solid-on-solid) models, including the dual transforms of XY-models with Villain and with cosine action. The method is based on a matching of the renormalization group (RG) flow of the candidate models with the flow of a bona fide KT model, the exactly solvable BCSOS model. We obtain high precision estimates for the critical couplings and other non-universal quantities. 
M. Hasenbusch, M. Marcu and K. Pinn