Functional equations of form factors for diagonal scattering theories Original Research Article

The form factor bootstrap approach is applied for diagonal scattering theories. We consider the ADE theories and determine the functional equations satisfied by the minimal two-particle form factors. We also determine the parameterization of the singularities in two-particle form factors. For A2(1) affine Toda field theory, which is the simplest non-self-conjugate theory, form factors are derived up to four-body ones and identification of the operator is done. Generalizing this identification to the ANN(1) affine Toda cases, we find the two-particle form factors. We also determine the additional pole structure of form factors which comes from the double pole of the S-matrices of the AN(1) theory. For AN theories, the existence of the conserved ZN+1 charge leads to the division of the set of form factors into N + 1 decoupled sectors.