Decoupling Solution to the Supersymmetric Flavor Problem without Color Instability

The supersymmetric flavor problem is elegantly solved by the decoupling scenario, where the first-two generation sfermions are much heavier than the third generation ones. However, such a mass spectrum is not stable against renormalization group evolution and causes extreme fine-tuning of the electroweak symmetry breaking. We present a mechanism which stabilizes the mass spectrum with such a large splitting, by introducing extra vector-like chiral multiplets of masses comparable to the first-two generation sfermions. The explicit models are constructed in a framework of the anomalous U(1) SUSY-breaking model.