The squared eigenfunctions of the massive Thirring model in laboratory coordinates

We demonstrate a simple procedure for finding the squared eigenfunctions of an integrable system and illustrate the method by deriving the squared eigenfunctions of the massive Thirring model. We give the formula for the inner products between the direct squared eigenfunction problem and its adjoint. We also demonstrate closure and express the variations of the potentials in terms of variations of the scattering data. (C) 1996 American Institute of Physics.