Wave-function renormalization for the Coulomb-gas in Wegner-Houghton's   RG method
  The RG flow for the sine-Gordon model is determined by means of the method of Wegner and Houghton in next-to-leading order of the derivative expansion. For small values of the fugacity this agrees with the well-known RG flow of the two-dimensional Coulomb-gas found in the dilute gas approximation and a systematic way of obtaining higher-order corrections to this approximation is given. 
I. Nandori, J. Polonyi, K. Sailer