VENEZIANO MODEL FOR PIPI-]PIS, WHERE S HAS ARBITRARY SPIN AND PARITY

The Veneziano model is applied to the reaction ππ→πS, where S is any particle of spin S, isospin 0 or 1. For particles with natural parity, P=(-1)S, we require that our amplitude not be coupled to any odd daughters. This fixes the relative magnitudes of the helicity amplitudes and constrains the particles S(ω,A2,) to lie on a trajectory which is parallel to the degenerate ρ and f trajectories. For particles with unnatural parity, P=-(-1)S, we demand that the amplitude satisfy the Adler consistency condition. This gives mass restrictions on the sequence of particles π,A1,. © 1969 The American Physical Society.