On the chiral phase transition in hadronic matter
  A qualitative analysis of the chiral phase transition in QCD with two massless quarks and non--zero baryon density is performed. It is assumed that at zero baryonic density, \rho=0, the temperature phase transition is of the second order. Due to a specific power dependence of baryon masses on the chiral condensate the phase transition becomes of the first order at the temperature T=T_{ph}(\rho) for \rho>0. At temperatures T_{cont}(\rho) > T > T_{ph}(\rho) there is a mixed phase consisting of the quark phase (stable) and the hadron phase (unstable). At the temperature T = T_{cont}(\rho) the system experiences a continuous transition to the pure chirally symmetric phase. 
M.N. Chernodub and B.L. Ioffe