Model Characterization and Dark Matter in the Secluded U(1)′ Model

We consider a class of U(1)'-extended MSSM in which the U(1)' symmetry is broken by a vacuum expectation values (VEVs) of four MSSM singlet fields. While one singlet field interacts with the MSSM Higgs fields, three of them interact only with each other in forming a secluded sector. Assigning universal U(1)' charges for three families, the anomaly cancellation condition requires exotic fields which are assumed to be heavy and decoupled. We discuss a variety of U(1)' charge assignments and anomaly cancellation, Z'/Z hierarchy, neutralinos and charginos as well as the Higgs sector. We realize that the typical spectra involve two CP-odd Higgs bosons lighter than about 200 GeV and 600 GeV respectively, which are mostly formed by the MSSM singlet fields. If the relic density of dark matter is saturated only by a neutralino, compatible solutions predict LSP neutralinos formed by the MSSM singlet fields in the mass scales below about 600 GeV, while it is possible to realize MSSM neutralino LSP above these mass scales. We identify A-funnel solutions in the MSSM singlet LSP solutions. These solutions can also yield considerable scattering cross-sections through the Higgs portal such that they can be tested in the ongoing direct dark matter detection experiments