Parity doubling of the nucleon and first-order chiral transition in dense matter

A new kind of first-order phase transition at finite baryon density is shown to occur using an effective lagrangian which simulates the parity doubling of the nucleon found recently is lattice QCD. Within the mean field approximation, we obtain a critical density of about five times the saturation density of nuclear matter. The implications of this phase transition to neutron star structure are discussed. (orig.)