Search

For the reaction\(\pi {\mathcal{N}} \to \pi \pi {\mathcal{N}}\) measured on an unpolarized target, there exists a ten-parameter family of transformations of the helicity amplitudes which preserves the six observable quantities. These transformations consist of a nine-parameter family, easily expressed in terms of two-dimensional matrices, which specify the orientation of the amplitudes in a four-dimensional space, and a one-parameter family which changes the relative amount ofS- andP-wave production. The consequences of this ambiguity for some recent analyses of π-π are discussed.

High energy scattering amplitudes are computed using the Harari model for the imaginary parts and fixed t dispersion relations for the real parts. This procedure induces a corrective term to the real part of the Regge amplitudes whose effects are investigated in π -nucleon and K-nucleon charge exchange reactions.