Diquarks in a quark model of the nucleus

The basic dynamical description of hadrons is generally believed to be given by QCD. Thus non-strange hadrons should be described as composite particles of almost massless quarks and gluons, a concept which is well established at least at high energies. At intermediate and low energies gluon and antiquark degrees of freedom are frozen in, and quarks will have an effective mass and an effective dynamics which bind them into 3-quark and quark-antiquark clusters, yielding the baryon resonances and the mesons. The conventional description of nuclei is then given by the multibaryon picture in which baryons interact by relatively weak forces commonly given by meson-exchange. The authors of this paper are interested in the question of whether this picture is really sufficiently complete in view of the underlying quark dynamics. In a nucleus the internal nucleon wave functions have such a large overlap, that a strong distortion of these particles can, at least naively, be expected. For this reason, the authors have developed a quark model of the nucleus, where the local confinement of quarks into hadrons is given up for global confinement into a bag of nuclear size and where the clustering into hadrons is produced by a quark-quark interaction of the pairing type