Bosonization of dimerized Hubbard chains
  The role of Klein factors is investigated for the bosonized Hamiltonian of the dimerized Hubbard model. Contrary to previous approaches we take into account their number changing property, i.e. we do not replace them by Majorana fermions. We show how to treat Klein factors in the framework of the self-consistent harmonic approximation, both for finite systems and in the thermodynamic limit. 
C. Mocanu, M. Dzierzawa, P. Schwab, and U. Eckern