Analyticity Properties of Feynman Diagrams

General discussion of the analyticity properties of Feynman diagrams. Cutting rules and the Cutkosky unitarity relations. Unstable particles and second sheet singularities. Dispersion relations and the Mandelstam representation. The analytic S-matrix theory and the bootstrap hypothesis.

Application of Moffat's Model to η → 3π and K → 3π Decays

Moffat's model for meson–meson scattering, satisfying the Mandelstam representation, crossing symmetry, and Regge behavior, is applied to η → 3π and K → 3π decays. It is found that agreement with the data is excellent when the model is used with Lovelace's trajectory, but not as good with Moffat's trajectory. The model is also applied to the process [Formula: see text], and fair agreement is found in the low energy region; however, since the model is unitary only at low energies, no strong conclusions can be reached in this case.