Nuclear matter in nontopological soliton models with quark-meson coupling

A system of nontopological solitons interacting through meson exchange is used to model dense nuclear matter. The models studied are of the Friedberg-Lee type, which exhibit dynamical bag formation due to the coupling of quarks to a scalar composite gluon field σ. It is shown in the Wigner-Seitz approximation that the high density behavior of such models depends essentially on the leading power of the quark-σ coupling vertex. By insisting that the parameters of any soliton model be chosen to reproduce single nucleon properties, this high-density behavior then selects a promising class of models that better fit the empirical results - the chiral chromodielectric models. The presence of a scalar meson is shown to provide saturation as well as an increase of the proton charge radius with nuclear density. We go beyond the usual Wigner-Seitz approximation by introducing the disorder necessary to reproduce the liquid state, using the significant structure theory of physical chemistry. We study nuclear matter, with particular interest in the transition to a quark plasma, showing that even the simplest version of the model provides a reasonable qualitative fit to both the empirical nuclear matter equation of state and single nucleon properties.