Probing Hamiltonian field redefinition on the nontrivial conformal   algebra
  The compatibility between the conformal symmetry and the closure of conformal algebras is discussed on the nonlinear sigma model. The present approach, above the basis of field redefinition employed in the Hamiltonian scheme, attempts the method of quantisation with intuitive picture. As a general field theoretic treatment, the consistency is ensured by means of the interesting features which are observed in the historical studies for the gauge-invariant conformal symmetry. The identification of conformal anomaly is also shown coincident with the conventional one approached within the path-integral formulation. 
Simon C. Lin, Feng Yin Li and Tsong Ming Liaw