THE SPECTRUM OF THE NUCLEONS AND THE STRANGE HYPERONS AND CHIRAL DYNAMICS

The spectra of the nucleons, Delta resonances and the strange hyperons are well described by the constituent quark model if in addition to t he harmonic confinement potential the quarks are assumed to interact b y exchange of the SU(3)(F) octet of pseudoscalar mesons, which are the Goldstone bosons associated with the hidden approximate chiral symmet ry of QCD. In its SU(3)(F) invariant approximation the pseudoscalar ex change interaction splits the multiplets of SU(6)(FS) x U(6)(conf) in the spectrum to multiplets of SU(3)(F) x SU(2)(S) x U(6)(conf). The po sition of these multiplets differs in the baryon sectors with differen t strangeness because of the mass splitting of the pseudoscalar octet and the different constituent masses of the u, d and s quarks that bre aks SU(3)F flavor symmetry. A description of the whole spectrum, to an accuracy of similar or equal to 4% or better, is achieved if one matr ix element of the boson interaction for each oscillator shell is extra cted from the empirical mass splittings. The ordering of the positive and negative parity states moreover agrees with the empirical one in a ll sectors of the spectrum. A discussion of the conceptual basis of th e model and its various phenomenological ramifications is presented.