Polarization properties of low energy amplitude for theπN→ππNreaction

Abstract

The theoretical study of cross sections for polarized-target measurements of πN → ππN reactions gives evidence that the interplay between the strong contribution from OPE mechanism and the one from isobar exchanges, which is equally strong within isobar half-widths energy region, must result in nontrivial polarization phenomena. The Monte-Carlo simulations for asymmetries inMeV/c with the use of theoretical amplitudes found as solutions for unpolarized data at P Lab < 500 MeV/c provide confirmations for significant effect.The effect is capable to discriminate between the OPE and isobar exchanges and it is sensitive to the OPE parameters in question. This leads to the conclusion that the decisive πN → ππN analysis, aiming at determination of ππ-scattering lengths, must combine both unpolarized data and polarization information. The appropriate measurements are shown to be feasible at the already existing CHAOS spectrometer. PACS number(s): 13.75.-n, 13.75.Gx, 13.75.LbSankt-Petersburg 1998

Convergence issues in baryon chiral perturbation theory for the reaction π + N → 2π + N

“…Two samples of fitted results for double differential cross-section data, d 2 σ/d dT , for different kinematic conditions are shown in Fig. The unpolarized cross-section T beam = 243 MeV π − + π p ---> + + π − + n measurements have limitations in this regard [18]. The subsequent theoretical results presented in this section can be regarded as predictions rather than fits.…”