Temperature and chemical potential

Abstract

Since the big bang the universe has cooled down substantially. Still, understanding QCD at high temperature and at high matter density is important for various reasons. One of them is obviously a better understanding of quarkand gluon matter shortly after the big bang and of the condensation of hadrons in the cooling process. Many objects in the universe like neutron stars supposedly have high enough density or temperature to expect that hadronic matter behaves differently compared to usual atoms. On earth very energetic collisions of heavy ions provide also possibilities to study matter under extreme conditions. Thus studying QCD at high temperature and density from first principles is a challenging task for the lattice approach. © 2010 Springer-Verlag Berlin Heidelberg.