MANIFESTATION OF THE PION POLE IN (P)OVER-BAR-P-](N)OVER-BAR-N CHARGE-EXCHANGE SCATTERING

A recent experiment at LEAR, the CERN Low Energy Antiproton Ring, has provided very precise differential cross-section data for the ($) over bar pp --> ($) over bar nn charge-exchange reaction. When performing the extrapolation procedure to the pion pole originally proposed by G.E Chew the data exhibit the same dynamical mechanism than the np --> pn line reversal reaction. The residue at the pole is consistent with the known value of the charged pi NN coupling constant, as expected from charge conjugation invariance.