11 Chapter 1: Introduction very different lines of reasoning point to something very interesting occuring in nuclear matter at high temperatures and densities. (a) (b) Figure 1.5: (a) Phase transition from confined baryonic/mesonic matter to quark/gluon matter from the mean field quantum hadrodynamics (QHD) approach of Walecka [71]; figure adapted from [79]. (b) A sharp rise in energy reminiscent of a phase transition is seen at T ≈ 160 MeV in Hagedorn’s statistical model [69]; figure adapted from [70]. Interestingly these disparate descriptions of nuclear matter T high energy density all obtain similar values for the transition temperature T$_{c}$ . Simple di- mensional analysis leads one to expect the temperature of such a QGP to be around Λ$_{QCD}$ ≈ 200 MeV, as this is a necessary momentum scale to resolve dis- tances of order the nucleon and at the same time is the scale of normal nuclear energy densities of 1 GeV/fm $^{3}$. Walecka yields ∼ 150 MeV [79]. Frautschi