HIGH-ENERGY MODELS PROCEEDING VIA BARYONIC EXCHANGES IN TERMS OF DIRECT-CHANNEL AMPLITUDES

The formulation of high-energy exchange models in terms of direct-channel amplitudes is applied to two-body reactions described by fermion Regge poles. It is shown that the analytic properties can be satisfied only with amplitudes determined by a pair of conspiring Regge trajectories. The asymptotic behaviour of physical quantities is examined in connection with the oscillating behaviour of scattering amplitudes. Besides allowing a generalization of well-known facts obtained from pseudoscalar-meson-nucleon scattering, our results constitute a very convenient parametrization of the helicity amplitudes, useful in the phenomenological analysis of two-body experiments at high energy with fermionic exchanges. © 1969 Società Italiana di Fisica.