Quark Model States and Low Energy Scattering

Abstract

In these lectures, based on work with R. Jaffe, I wish to discuss the connection between the discrete mass eigenstates which are calculated in an approximate quark-gluon model and the observed low energy hadron-hadron scattering in the same mass region The problem we claim to have solved can be stated crudely: where are the exotics? The quark model predicts exotic states, for example, in the I=2 ππ system at 1.15 GeV; the I=2 ππ S-wave phase shift, on the other hand, shows no sign of interesting behavior up to an energy of about 1.5 GeV, by which time it is approximately — .5 radians. Similar comments apply to other exotic channels. Our solution of this problem rests on a new method of analyzing low energy hadron-hadron scattering, applicable to multitwo-body channels but not to genuine three body channels. It is simplest in its application to single channel systems, and therefore most reliably applicable to low energies and exotic channels.