Bound State Spectrum of Massive Thirring Model in Rest Frame
  The bound state spectrum of the massive Thirring model is studied in the framework of the canonical quantization in the rest frame. First, we quantize the field with the massless free fermion basis states. Then, we make a Bogoliubov transformation. This leads to the natural mass renormalization. The bound state spectrum is analytically solved by the $q\bar{q}$ Fock space. It is found that the spectrum has the right behaviors both for the weak and for the strong coupling limits after the appropriate wave function regularization. This regularization is quite clear and the treatment is self-consistent for the bound state problem compared to other regularizations. Further, we show that the interaction between $q\bar{q}$ bosons is always repulsive and therefore there is no bound state in the four fermion ($qq \bar q \bar q$) Fock space. This confirms that there is only one bound state in the massive Thirring model. 
Makoto Hiramoto and Takehisa Fujita