Renormalization of Hamiltonian Field Theory; a non-perturbative and   non-unitarity approach
  Renormalization of Hamiltonian field theory is usually a rather painful algebraic or numerical exercise. By combining a method based on the coupled cluster method, analysed in detail by Suzuki and Okamoto, with a Wilsonian approach to renormalization, we show that a powerful and elegant method exist to solve such problems. The method is in principle non-perturbative, and is not necessarily unitary. 
Amir H. Rezaeian and Niels R. Walet