Scattering amplitudes of the gross-neveu and nonlinear σ-models in higher orders of the

B. Berg, M. Karowski, V. Kurak, P. Weisz
1978 Physics Letters B  
The exact S-matrices proposed by Alexander and Alexey Zamolodchikov for the nonlinear o-model and Gross-Neveu model are verified to order 1IN 2 perturbation theory. This provides a good check of the nature of the bound state spectrum.
doi:10.1016/0370-2693(78)90916-4 fatcat:qca6juoszbex7n42jmym476gzu