The magnitude of the parity-violating nucleon-pion couplingN 0-, and final-state interactions

Abstract

The purpose of this letter is to present a new estimate for the magnitude ot the parity-violating amplitude ~ pT:(henceforth denoted by N~ based on the inclusion of final-state interactions. I t is important to know the magnitude of iV ~ because pion exchange contributes to the long-range par t of the weak parity-violating internucleon potential which manifests itself in parity-violating nuclear transitions (~). In a previous paper (2) TROFIMENKOFF and the author showed that the inclusion of final-state interactions in nonleptonic hyperon decay amplitudes led to a good fit of Sand P-wave amplitudes to experiment, in contrast to the mediocre fit obtained in the conventional current-algebra-PCAC method. Our conclusion in this letter is that the inclusion of final-state interactions, which has been shown (2) both to be essential and to lead to a much improved agreement with experiment for nonleptonic hyperon decays, significantly modiiics the older estimate for N ~ based on the current-algebraPCAC method (3.4). We now briefly review our method for including the effect of final-state interactions on parity-violating nonleptonie hyperon decays and the parity-violating AS----0 process j~--~pT:-. Our notation here is identical with that of ref. {2). This paper (2) should be referred to for general orientation and also specific results. The matrix element T for the parity-violating processes a ~ f l + ~(c) (we are t reat ing both AS = 0 and AS : 1 amplitudes here, because we shall later relate the AS = 0 to the AS-----1 amplitudes) with corresponding momenta P~-+P~-~-k and masses M ~ M~ + m can be wri t ten as