Abstract
Phase structure of quark matter which consists of two light flavors (up and down) in the instanton vacuum is investigated at finite chemical potential (μ) and zero temperature (T). The finite μ form factors from the zero mode quark are calculated without approximation. Phase structures for N_c=3 and for N_c=2 are evaluated using thermodynamic potential in mean-field approximation. It is found that in all the cases with finite current quark mass the doubly symmetry broken (DSB) phase in which both chiral and color symmetries are broken can be realized between pure chiral and pure color symmetry broken phase. It is noteworthy that a finite current quark mass raises the pressure in DSB phase, and in consequence, the DSB region becomes much wider than the chiral limit.
