P(P)OVER-BAR ANNIHILATION INTO PI(-)PI(0) IN A HADRON-EXCHANGE MODEL()PI()

Proton-antiproton annihilation into three pions is studied in a hadron -exchange model. An uncorrelated three-pion channel is added to the tw o-meson channels considered in previous calculations. Initial-state in teractions are taken into account in a distorted-wave Born approximati on, using the most complete version of the Julich <N(N)over bar> model . The uncorrelated three-pion channel adds a 10% contribution to the < p(p)over bar> --> pi(+)pi(-)pi(0) total cross section. The relative br anching ratios for annihilation into three uncorrelated pions from sta tes of equal orbital angular momentum, but different total angular mom entum and spin, are also calculated. They compare semiquantitatively w ith the corresponding quantities calculated from the phase-space compo nents of phenomenological amplitudes fitted to experimental data for s topped antiprotons. It is concluded that hadron exchange provides a vi able model for annihilation into three non-resonant pions. (C) 1997 El sevier Science B.V.