Combining anomaly and Z′ mediation of supersymmetry breaking

We propose a scenario in which the supersymmetry breaking effect mediated by an additional U(1)′ is comparable with that of anomaly mediation. We argue that such a scenario can be naturally realized in a large class of models. Combining anomaly with Z′ mediation allows us to solve the tachyonic slepton problem of the former and avoid significant fine tuning in the latter. We focus on an NMSSM-like scenario where U(1)′ gauge invariance is used to forbid a tree-level μ term, and present concrete models, which admit successful dynamical electroweak symmetry breaking. Gaugino masses are somewhat lighter than the scalar masses, and the third generation squarks are lighter than the first two. In the specific class of models under consideration, the gluino is light since it only receives a contribution from 2-loop anomaly mediation, and it decays dominantly into third generation quarks. Gluino production leads to distinct LHC signals and prospects of early discovery. In addition, there is a relatively light Z′, with mass in the range of several TeV. Discovering and studying its properties can reveal important clues about the underlying model.