Discontinuity of the Wilson string tension in the 4-dimensional lattice pure gauge Potts model

We consider the 4-dimensional q-state pure gauge Potts model. For q large enough, we give a new proof of the existence of a unique coupling constant βt, where a first order phase transition occurs. Moreover we prove the following new results: This string tension is discontinuous at βt, the Wilson parameter exhibits at βt a direct transition from an area law decay (quark confinement) to a perimeter law decay (quark deconfinement). (orig.)