Gravitational divergences as a mediator of supersymmetry breaking

Gravitational divergences associated with singlet fields in supersymmetric theories are reexamined, and their possible contributions to the low-energy effective theory are pointed out. We demonstrate that such divergences are not necessarily harmful and that Planck-scale physics could play an important role in models of low-energy supersymmetry breaking via a radiatively induced tadpole term in the scalar potential. In this case, gravitational divergences play the role of the supersymmetry breaking mediator, leading to a simple realization of the so-called messenger model. We also point out a new mechanism for the generation of mass terms for the Higgs fields in models of low-energy supersymmetry breaking, as well as a horizontal messenger mechanism in which the horizontally charged scalars are rendered heavy. Implications to the flavor problem in supersymmetric models are also discussed.