The form factor program: A review and new results,the nested <Emphasis Type="Italic">SU</Emphasis>(<Emphasis Type="Italic">N</Emphasis>) off-shell Bethe ansatz and the 1/<Emphasis Type="Italic">N</Emphasis> expansion

The purpose of the “bootstrap program” for integrable quantum field theories in 1+1 dimensions is to construct a model explicitly in terms of its Wightman functions. We illustrate this program here mainly in terms of the SU(N) Gross-Neveu model. We construct the nested off-shell Bethe ansatz for an SU(N) factoring S-matrix and consider the problem of how to sum over intermediate states in the short-distance limit of the two-point Wightman function for the sinh-Gordon model. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 155, No. 1, pp. 13–24, April, 2008.