  The phase diagram of strongly interacting matter is explored as a function of
temperature and baryon number density. We investigate the possible simultaneous
formation of condensates in the conventional quark--anti-quark channel
(breaking chiral symmetry) and in a quark--quark channel leading to color
superconductivity: the spontaneous breaking of color symmetry via the formation
of quark Cooper pairs. We point out that for two massless quark flavors a
tricritical point in the phase diagram separates a chiral symmetry restoring
first order transition at high densities from the second order transition at
high temperatures. Away from the chiral limit this tricritical point becomes a
second order phase transition with Ising model exponents, suggesting that a
long correlation length may develop in heavy ion collisions in which the phase
transition is traversed at the appropriate density.
