Polarization properties of low energy amplitude for the pi N ->pi pi N reaction - art. no. 055203

The theoretical study of cross sections for polarized-target measurements o f pi N-->pi pi N reactions gives evidence that the interplay between the st rong contribution from the one-pion exchange (OPE) mechanism and the one fr om isobar exchanges, which is equally strong within the isobar half-width e nergy region, must result in nontrivial polarization phenomena. The Monte C arlo simulations for asymmetries in the pi(-)p up arrow-->pi(-) pi(+) n rea ction at P-lab=360 MeV/c with the use of theoretical amplitudes found as so lutions for unpolarized data at P-lab<500 MeV/e provide confirmations for a significant effect. The effect is capable of discriminating between the OP E and isobar exchanges and it is sensitive to the OPE parameters in questio n. This leads to the conclusion that the decisive pi N-->pi pi N analysis, aiming at a determination of pi pi-scattering lengths, must combine both un polarized data and polarization information. The appropriate measurements a re shown to be feasible at the already existing CHAOS spectrometer.