Nonpolynomial Lagrangians with isospin

We apply (Laplace, Fourier, …) transform methods to obtain compact representations of the perturbationS‐matrix elements for interaction Lagrangians which are general nonpolynomial functions of isospin multiplets. In order to illustrate the power and simplicity of the method for coping with the isospin complications, we have treated several examples in detail, and these include the commonly used parametrizations of the unitary chiralSU(2)⊗SU(2) SU(2)⊗SU(2) transformations.