The author discusses the application of the quark cluster model to the baryon-baryon interaction. The short-range repulsion and spin-orbit force in the nucleon-nucleon potential are shown to be well described by the quark-quark interaction and quark exchange between the two nucleons. An extension of the study to systems with strangeness is made. There the author studies more details about the effect coming from the composite structure of the baryon and the quark-quark interaction. The dihyperon, which is a flavour SU(3) singlet state, is also discussed in terms of the quark cluster model. Finally the effects of quark degrees of freedom in nuclei, especially on the electromagnetic properties of the deuteron, are studied and compared with the results of conventional nuclear theory.

https://iopscience.iop.org/article/10.1088/0034-4885/52/1/001/pdf

Study of baryon-baryon interactions and nuclear properties in the quark cluster model

Two-body interaction currents and nuclear magnetic moments

Nuclear magnetic resonance in metals

: The deuteron form factor is calculated in a one-pionexchange (OPE) approximation using single-variable unsubtracted dispersion relations in the squared-momentum-transfer variable. As a first step, the imaginary parts of the form factors are presented in terms of the four invariants of the deuteron-nucleon (d-N) vertex. The resulting equations are compared in detail with similar expressions obtained from the Jankus potential theory, and a clear understanding of the precise way in which the d-N invariants play the role of the deuteron wave function emerges, enabling us to obtain relativistic wave functions. This comparison also shows the presence of new relativistic terms not included in the Jankus results (in particular, a new term appears in the magnetic moment). Then, the imaginary parts of the d-N vertex invariants are calculated numerically. In this calculation the OPE contribution in its anamalous region is calculated exactly, while the contributions above the normal threshold are obtained by an educated guess based on sum rules which the invariants are assumed to satisfy. Finally, using these results, the form factors are calculated numerically. With the assumption of unsubtracted dispersion relations, it is necessary to assume only the charge and mass of the deuteron, and the pion-nucleon coupling constant, in order to completely determine the form factors. The numerical results for the magnetic and quadrupole moments agree with experiment to within 2%; the D-state probability if 5.5% but is not very reliably determined, and the other results, while less good, are still quite reasonable. (Author)

R. J. Blin‐Stoyle

Papers

Theories of Nuclear Moments