Potentials between static SU(3) sources in the fat-center-vortices model

The potentials between static sources in various representaions in SU(3) arecalculated based on the fat-center-vortices model of Faber, Greensite andOlejnik. At intermediate distances, most distributions of the flux withinvortices lead to potentials that are qualitatively in agreement with ``Casimirscaling,'' which says that the string tension is proportional to the quadraticoperator of the representation. However, at the quantitative level, violationsof Casimir scaling are generally much larger than those seen in numericalsimulations, indicating that additional physical input to thefat-center-vortices model is required. At large distances, screening occurs forzero-triality representations; for the representations with non-zero trialitythe string tension equals that of the fundamental representation. Some rather``unphysical,'' flux distributions can lead to violations of Casimir scaling atintermediate distances and violations of the expected ordering ofrepresentations at large distances.Comment: Compare to the previosly archived edition, I have extended the work to include various classes of vortex flux distribution which has resulted in some interesting new results on the relevance of the flux distributions for the physical consequences of the model. This version corresponds to the published versio