Density dependence of quark masses and stability of color-flavor locked phases

Considering the density dependence of quark masses, we investigate the color-flavor-locked matter and its stability relative to the ( unpaired ) strange quark matter. We find that, when the current mass of strange quark $m_s$ is small, the strange quark matter remains stable for the moderate baryon densities. When $m_s$ is large, the gapless phase of the color-flavor-locked matter is found to be difficult to be stable. A schematic phase diagram of three-flavor quark matter is presented, in which the color-flavor-locked phase region is suppressed in comparison with the previous results.