PHI-PI PRODUCTION IN (P)OVER-BAR-P ANNIHILATION FROM S-STATES AND P-STATES AND IN J PSI DECAYS/

Recent experiments at LEAR have found surprisingly large branching rat ios for reactions (N) over bar N --> phi pi from S-wave initial states while no phi pi production is observed from P states of the (p) over bar p system. Also, no phi pi is seen in radiative J/psi decays even t hough the rate for omega pi is substantial. We calculate the phi pi pr oduction rates for these three cases via KK intermediate states and K (K) over bar rescattering using the dispersion relation technique; we find that the large phi pi rate in p (p) over bar annihilations from S states can be reproduced with a reasonable cut-off for the dispersio n integral; for J/psi decays the calculated phi pi rate is compatible with the observed upper limit. We would, however, expect phi pi to be seen from (p) over bar p P-states, in contrast to experimental finding s. Yet the branching ratio for (p) over bar p --> K(K) over bar via i sospin I = 1 of (p) over bar p, P-1(1) state is not known; and therefo re no definite conclusion can be drawn. We also compare the Dalitz plo ts we obtain for direct phi production and for phi production via resc attering. Clear differences between the two theoretical distributions are observed; yet very high precision data would be required to establ ish the origin - direct production or rescattering - of the phi mesons . This observation supports the use of the isobar model in data analys es.