SU(4) pure-gauge phase structure and string tensions

We present numerical evidence that the SU(4) pure-gauge dynamics has a fini te-temperature first-order phase transition. For a 6 x 20(3) lattice, this transition occurs at the inverse-square coupling of 8/g(2) similar to 10.79 . Below this and above the known bulk phase transition at 8/g(2) similar to 10.2 is a confined phase in which we find two different string tensions, o ne between the fundamental 4 and 4* representations and the other between t he self-dual diquark 6 representations. The ratio of these two is about 1.5 . The correlation in the adjoint representation suggests no string forms be tween adjoint charges.