A new interpretation of Bethe ansatz solutions for massive Thirring   model
  We reexamine Bethe ansatz solutions of the massive Thirring model. We solve equations of periodic boundary conditions numerically without referring to the density of states. It is found that there is only one bound state in the massive Thirring model. The bound state spectrum obtained here is consistent with Fujita-Ogura's solutions of the infinite momentum frame prescription. Further, it turns out that there exist no solutions for string-like configurations. Instead, we find boson boson scattering states in 2-particle 2-hole configurations where all the rapidity variables turn out to be real. 
Takehisa Fujita, Kenji Yamamoto, Yasuyuki Sekiguchi