PARITY NONCONSERVATION IN THE PP SYSTEM AT LOW-ENERGY - CRITICAL REMARKS ABOUT DIRECT QUARK APPROACHES

Several papers dealing with predictions for the parity-non-conserving longitudinal asymmetry in pp scattering at low energy, using either a quark-model approach or the concept of parity admixture of vector meso ns, are reviewed. About 10 papers which are concerned with the determi nation of the sign are discussed here. It is shown that they predict a sign for the asymmetry which is likely to be incorrect and, in any ca se, in contradiction with the standard theoretical understanding of th e sign actually determined by experiment. The relationship of these ap proaches with that based on the old factorization approximation is emp hasized. In this order, many details are given, and obviously special attention is given to the sign prediction (conventions, definitions, p hases, etc.).