Model characterization and dark matter in the secluded U(1)' model

We consider a class of U(1)'-extended minimal supersymmetric extension of the Standard Model (MSSM) in which the U(1)' symmetry is broken by vacuum expectation values of four MSSM singlet fields. While one MSSM 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, charginos and the Higgs sector. We find 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. One can classify the implications in three scenarios. Scenario I involves NLSP charginos, while Scenario II involves charginos which do not participate coannihilation processes with the LSP neutralino. These two scenarios predict MSSM singlet LSP neutralinos, while Scenario I leads to larger scattering cross sections of dark matter. Scenario III has the solutions in which the MSSM neutralinos are considerably involved in LSP decomposition which yields very large scattering cross section excluded by the direct detection experiments.

Automated summary

We study a type of U(1)'-extended minimal supersymmetric extension of the Standard Model (MSSM) in which the U(1)' symmetry breaking is achieved by vacuum expectation values of four MSSM singlet fields. The U(1)' charges are assigned to the three families in a universal way, and to satisfy the anomaly cancellation condition, heavy and decoupled exotic fields are introduced. We discuss different charge assignments, anomaly cancellation, Z'/Z hierarchy, neutralinos, charginos, and the Higgs sector. The typical spectra contain two CP-odd Higgs bosons, predominantly composed of MSSM singlet fields, with masses below 200 GeV and 600 GeV, respectively. The relic density of dark matter can be saturated by neutralinos, where the LSP neutralinos are predominantly formed by MSSM singlet fields below 600 GeV, while MSSM neutralino LSP can be realized above this mass scale. We classify the implications into three scenarios: Scenario I involves NLSP charginos, Scenario II involves charginos that do not participate in coannihilation processes with the LSP neutralino, and Scenario III involves MSSM neutralinos with large scattering cross sections excluded by direct detection experiments.