Nuclear Structure Studies in the Quark-Meson Coupling Model

Abstract

The Quark-Meson Coupling (QMC) model provides a description for nuclear structure starting from the level of quarks within nucleons so that the nuclear interaction is described through the exchange of mesons. Apart from the central contribution derived from the model, spin-orbit and spin-tensor terms arise naturally within the QMC framework and are fully expressed in terms of existing QMC parameters, thus adding no new parameters in the model. The latest version, QMCp-III, further derives the pairing interaction from the QMC model, so that the total number of parameters is significantly reduced to only five. The focus of this research is on the parameter optimisation of the QMC model throughout the stages of its development and its implementation for the study of finite nuclei. The final sets of QMC parameters at each stage, consistent with nuclear matter properties, were determined using a robust optimisation procedure and then relevant statistics such as parameter errors and correlations were computed. The model was then used to investigate several nuclear properties for even-even nuclei across the present nuclear landscape. The model showed a continuous improvement in comparison with experiment as the model developed, reproducing experimental data for various energy and radius observables even for nuclei which were not included in the fit. In QMCp-III, binding energy and rms charge radius deviations from experiment were decreased to 0.3% and 0.5%, respectively, for all even-even nuclei with available data. Furthermore, calculations were extended for nuclear observables which had not been part of the fitting procedure. QMC results for separation energies and deformations up to the superheavy region, were shown to be compatible with data, as well as with results from other existing nuclear models.