Constraints on ultraviolet-stable fixed points in supersymmetric gauge theories

We consider the possibility that some supersymmetric gauge theories which are not asymptotically free can be governed by ultraviolet-stable fixed points. If this scenario can be realized, gaugino masses will exhibit power-law running with scale, providing a possible solution to the supersymmetric flavor problem. While naive perturbative calculations hint at the appearance of ultraviolet-stable fixed points in certain theories, there are strong constraints following from limits on the scaling dimensions of gauge-invariant operators, positivity of central charges, and Cardy's conjectured constraint on the flow of the Euler coefficient in the stress tensor trace anomaly. Also, we prove that if ultraviolet-stable fixed points do exist, they cannot occur in the perturbative regime of a renormalizable model, and that all-orders results in the limit of large numbers of chiral superfields are necessarily inconclusive. However, we argue that the general idea of ultraviolet-stable fixed points in supersymmetric gauge theories is viable, and exhibit models that can satisfy all known constraints.