1. J. Iliopoulos:Nuovo Cimento,52 A, 192 (1967). The unitary equation used in this paper, eq. (22), has the wrong sign. Figure 1 and eqs. (34) and (35) should be changed accordingly.
2. S. Weinberg:Phys. Rev. Lett.,17, 616 (1966);N. N. Khuri:Phys. Rev.,153, 1477 (1967); For previous calculations including unitarity corrections, see:T. Akiba andK. Kang:Phys. Lett.,25 B, 35 (1967); and to be published;J. Sucher andC.-H. Woo:Phys. Rev. Lett.,18, 723 (1967);A. Donnachie: CERN preprint TH. 804 (1967).
3. We thank Dr.A. Martin for having pointed out this point to us.
4. The threshold behaviour of the partial-wave amplitudes can be shown if one uses the analyticity domain of the scattering amplitude proved byMartin, with the further assumption that the amplitude is bounded at threshold. For a simple and elegant proof, see:P. Moussa andR. Stora:Lectures given at the International School of Elementary-Particle Physics (Herceg Novi, 1966).
5. We have written the constant term in the formA−2E whereA represents the constant term in the expansion of the on-the-mass-shell amplitude. The same holds for the termD+E.