RESONANCE EXTINCTION AND EFFECTS OF DRIVING FORCES IN FINAL STATE INTERACTIONS

The absence of the rho resonance in the π+π- subsystem of the π+π-π- final state produced by pn annihilation has prompted the investigation of resonance extinction in final state interactions. Resonance extinction is shown to be a general feature of a simple dispersion theoretic model. The qualities of the two-particle amplitude necessary for the corresponding decay amplitude not to have resonance extinction are discussed. An important factor throughout is the structure of the vertex function, i.e. the decay amplitude with no final state interaction. We reexamine, using explicit models of the two-particle amplitude and vertex functions with structure, the widespread conjecture due originally to Watson, that attractive forces enhance a decay amplitude. © 1969.