9 Chapter 1: Introduction Figure 1.4: Experimental verification of SU(3) as the gauge group of QCD from four jet events measured at LEP. N$_{c}$ , C$_{F}$ , and T$_{F}$ are properties of the group struc- ture functions f and generators T defined by f $^{abc}$f ∗ abd = δ $^{cd}$N$_{c}$ , ( T $^{a}$T † $^{a}$)$_{ij}$ = δ$_{ij}$C$_{F}$ , and Tr ( T $^{a}$T † $^{b}$) = δ $^{ab}$T$_{F}$ , where repeated indices are summed over. Groups with N$_{c}$ = 3 are excluded by decay ratios while S0(3) and U(1)$_{3}$ do not have the correct ratios of group theoretic factors. Figure adapted from [44]. 1.3 QCD Phase Diagram The possibility of a new state of nuclear matter accessible through the collisions of heavy nuclei has a long history (see [67] and references therein). From