Gösta Gustafson and Carsten Peterson
Rescattering effects in the decay of A1
Nuclear Physics B116, 301-316 (1976)

Rescattering effects in the 3π system in the A1 region are studied with a method, which fulfils unitarity and has the proper analytic structure. Fairly small effects are obtained which confirm the result found in amplitude analyses, neglecting rescattering corrections, that the phases of the JP = 1+ amplitudes vary only very little over the A1 region. Similar results hold for the Q enhancement.