Tests of the One-Pion-Exchange Model

Abstract

The original Chew-Low proposal of a pion pole in the collision matrix at unphysical momentum transfer has evolved into a "generalized Born approximation" for one-pion exchange (OPE). This predicts that the collision amplitude will be independent of the total center-of-mass energy $W$ for the reaction. The author describes tests of this prediction for the process $\pi +N\to N+2\mathrm{}\pi$, where the final dipion mass is in the vicinity of the $\rho$ resonance at 750 MeV, using data for incoming pion momenta of 1.4, 1.7, and 3.0 BeV/c. The results agree with the model except for a variation with $W$ of the angular distribution of the dipion decay with respect to the incident $\pi$ direction.