PHASE TRANSITION PATTERNS OF NUCLEAR MATTER BASED ON EXTENDED LINEAR SIGMA MODEL

We study systematically various types of phase transitions in nuclear matter at finite temperature T and baryon chemical potential mu based on the extended linear sigma model with, nucleon degrees of freedom. It is shown that there are three types of phase transitions in nuclear matter: the chiral symmetry nonrestoration (SNR) at high temperature, the well-known liquid-gas (LC) phase transition at sub-saturation density and the Lifshitz phase transition (LPT) from the fully-gapped state to the state with Fermi surface. Their phase diagrams are established in the (T, mu)-plane and their physical properties are investigated in detail. The relationship between the chiral phase transition and the LC phase transition in nuclear matter is discussed.