The spectrum of the nucleons and the strange hyperons and chiral dynamics

• Published in: Physics reports 1996-04, Vol.268 (4), p.263-303
• Main Authors: Glozman, L.Ya, Riska, D.O.
• Format: Article
• Language: English
• ISSN: 0370-1573; 1873-6270
• DOI: 10.1016/0370-1573(95)00062-3

The spectra of the nucleons, Δ resonances and the strange hyperons are well described by the constituent quark model if in addition to the harmonic confinement potential the quarks are assumed to interact by exchange of the SU(3) F octet of pseudoscalar mesons, which are the Goldstone bosons associated with the hidden approximate chiral symmetry of QCD. In its SU(3) F invariant approximation the pseudoscalar exchange interaction splits the multiplets of SU(6) FS × U(6) conf in the spectrum to multiplets of SU(3) F × SU(2) S × U(6) conf. The position of these multiplets differs in the baryon sectors with different strangeness because of the mass splitting of the pseudoscalar octet and the different constituent masses of the u, d and s quarks that breaks SU(3) F flavor symmetry. A description of the whole spectrum, to an accuracy of − 4% or better, is achieved if one matrix element of the boson interaction for each oscillator shell is extracted from the empirical mass splittings. The ordering of the positive and negative parity states moreover agrees with the empirical one in all sectors of the spectrum. A discussion of the conceptual basis of the model and its various phenomenological ramifications is presented.