Soliton Models of Hadrons

Abstract

Conventional perturbation theory has provided the foundations and the basic tool in the application of field theory to the weak interactions of leptons. While it is hoped that field theory will also eventually yield a unified and complete description of hadron physics, it is as yet unclear which field theory one should take and what the best point of attack to such a theory should be. The impressive success of the quark model would favor the identification of quarks with the underlying constituents of hadronic matter and the unquestioned success of the principle of local gauge invariance would then lead to the choice of a field theory of quarks and gauge fields. An esthetical difficulty facing this approach is the relationship between quarks and leptons or, better, the lack of it, and a practical problem is the present day unobservability of quarks and gauge mesons as independent entities. One could speculate that these two problems will actually solve each other, e.g., by the identification of quarks with leptons, but such interesting options appear for the moment to be unfeasible. Inevitably, quark confinement (even if temporary, i.e.,to be followed by quark liberation at higher energies) presents itself as an important aspect of hadron dynamics.

Lecture given at XV.Internationale Universitätswochen für Kernphysik,Schladming,Austria, February 16–27, 1976.