Gauge Mediation in F-Theory GUT Models
  We study a simple framework for gauge-mediated supersymmetry-breaking in local GUT models based on F-theory 7-branes and demonstrate that a mechanism for solving both the \mu and \mu/B_{\mu} problems emerges in a natural way. In particular, a straightforward coupling of the messengers to the Higgs sector leads to a geometry which not only provides us with an approximate U(1)_{PQ} symmetry that forbids the generation of \mu at the GUT scale, it also forces the SUSY-breaking spurion field to carry a nontrivial PQ charge. This connects the breaking of SUSY to the generation of \mu so that the same scale enters both. Moreover, the messenger sector naturally realizes the D3-instanton triggered Polonyi model of arXiv:0808.1286 so this scale is exponentially suppressed relative to M_{GUT}. The effective action at low scales is in fact precisely of the form of the "sweet spot supersymmetry" scenario studied by Ibe and Kitano in arXiv:0705.3686. 
Joseph Marsano, Natalia Saulina, Sakura Schafer-Nameki