  In the limit of a large number of colors, N_c, we suggest that gauge theories
can exhibit several distinct phases at nonzero temperature and quark density.
Two are familiar: a cold, dilute phase of confined hadrons, where the pressure
is ~ 1, and a hot phase of deconfined quarks and gluons, with pressure ~ N_c^2.
When the quark chemical potential mu ~ 1, the deconfining transition
temperature, T_d, is independent of mu. For T < T_d, as mu increases above the
mass threshold, baryons quickly form a dense phase where the pressure is ~ N_c.
As illustrated by a Skyrme crystal, chiral symmetry can be both spontaneously
broken, and then restored, in the dense phase. While the pressure is ~ N_c,
like that of (non-ideal) quarks, the dense phase is still confined, with
interactions near the Fermi surface those of baryons, and not of quarks. Thus
in the chirally symmetric region, baryons near the Fermi surface are parity
doubled. We suggest possible implications for the phase diagram of QCD.
