Hadronic matter in a meson-nucleon-quark model

The ground state of hadronic matter is invested in a mean field approximation to a meson-nucleon-quark model. In this model hadronic matter is approximated, at very low densities by a Fermi gas of nucleons interacting via the exchange of sigma and omega mesons and at high densities by a Fermi gas of free massless quarks. At intermediate densities a metastable phase is assumed to exist consisting of a mixture of nucleons and quarks both interacting via the exchange of sigma and image mesons. The transition between these phases is obtained by introducing density dependent nucleon and quark probabilities. The nucleon probability decreases from one to zero while the quark probability is increasing from zero to one when the hadron density changes from zero to infinity. The model successfully describes hadronic matter over a wide range of densities, exhibiting the different phases suggested by QCD, and describes the quark degrees of freedom which get important at the high density phase of hadronic matter. 5 figs