Abstract
The general Next-to-Minimal Supersymmetric Standard Model (NMSSM) describes the singlino-dominated dark-matter (DM) property by four independent parameters: singlet-doublet Higgs coupling coefficient λ, Higgsino mass μtot, DM mass {m}_{{tilde{chi}}_1^0} , and singlet Higgs self-coupling coefficient κ. The first three parameters strongly influence the DM-nucleon scattering rate, while κ usually affects the scattering only slightly. This characteristic implies that singlet-dominated particles may form a secluded DM sector. Under such a theoretical structure, the DM achieves the correct abundance by annihilating into a pair of singlet-dominated Higgs bosons by adjusting κ’s value. Its scattering with nucleons is suppressed when λv/μtot is small. This speculation is verified by sophisticated scanning of the theory’s parameter space with various experiment constraints considered. In addition, the Bayesian evidence of the general NMSSM and that of Z3-NMSSM is computed. It is found that, at the cost of introducing one additional parameter, the former is approximately 3.3 × 103 times the latter. This result corresponds to Jeffrey’s scale of 8.05 and implies that the considered experiments strongly prefer the general NMSSM to the Z3-NMSSM.
Highlights
SI and spin-dependent (SD) cross-sections rely on Higgsino mass in different ways
The first three parameters strongly influence the DM-nucleon scattering rate, while κ usually affects the scattering only slightly. This characteristic implies that singlet-dominated particles may form a secluded DM sector
Motivated by the increasingly tight limitation of the direct detection experiments on traditional neutralino DM in the natural MSSM and Z3-Next-to-Minimal Supersymmetric Standard Model (NMSSM), the Z3-NMSSM is extended in the present work by adding a μHu · Hd term in its superpotential, and whether the Singlino-dominated neutralino can act as a feasible DM candidate is studied
Summary
The GNMSSM augments the MSSM by a gauge singlet superfield Sthat does not carry any leptonic or baryonic number. It is noticeable that a non-minimal coupling χ of a Higgs bilinear to gravity was introduced to implement a superconformal symmetry in the GNMSSM [28, 29], and this coupling could drive inflation in the early universe [30] In this case, the extra μ-term is connected with χ via gravitino mass m3/2, i.e., μ=. Above 1 TeV is considered in this paper to simplify the analysis of DM phenomenology This case is a theoretical hypothesis, and it can be realized by setting Aλ a significant value, e.g., Aλ = 2 TeV in the following numerical study. In the case of very massive gauginos and |m2χ01 − μ2tot| λ2v2, the following approximations for the Singlino-dominated χ01 [42,43,44] are obtained: 2κ λ μeff mχ.
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