Nuclear Matter at High Densities and Temperature

Abstract

The properties of nuclear matter for high densities and high temperatures are discussed. We concentrate especially on the possibility of pion condensation, Lee-Wick condensation and quark matter. We show that the same diagrams which lead to pion condensation provide a shielding aginst pion condensation if the diagrams coming from antisymmetrization are included up to the same order. While the RPA bubble series leads to pion condensation the bubbles inside the bubbles screen against it. The same is true for the Lee-Wick condensation which is a polarization of nuclear matter with the quantum numbers (scalar and isoscalar) of the a-meson. Finally we discuss quark matter at high densities and high temperatures and explore experimental possibilities to detect it in relativistic heavy-ion collisions.