Critical Analyses of Order Parameter and Phase Transitions at High Density in Gross-Neveu Model**The project partially supported by National Natural Science Foundation of China

Abstract

By critical analyses of the order parameter of symmetry breaking, we have researched the phase transitions at high density in and Gross-Neveu (GN) model and shown that the gap equation obeyed by the dynamical fermion mass has the same effectivenesss as the effective potentials for such analyses of all the second order and some special first order phase transitions. In the meantime we also further ironed out a theoretical divergence and proven that in model a first order phase transition does occur in the case of zero temperature and finite chemical potential.