Abstract
We study properties of the lightest neutralino (χ0) and calculate its cosmological relic density in a supersymmetric U(1)′ model with a secluded U(1)′ breaking sector (the S-model). The lightest neutralino mass is smaller than in the minimal supersymmetric standard model; for instance, mχ0≲100 GeV in the limit that the U(1)′ gaugino mass is large compared to the electroweak scale. We find that the Zχ0χ0 coupling can be enhanced due to the singlino components in the extended neutralino sector. Neutralino annihilation through the Z-resonance then reproduces the measured cold dark matter density over broad regions of the model parameter space.
Highlights
Recent mapping of the Cosmic Microwave Background (CMB) anisotropy [1] has provided precision information on the densities of matter and dark energy in the Universe
In this letter we investigate the properties of the lightest neutralino and evaluate its relic density3 in an extended model of the Minimal Supersymmetric Standard Model (MSSM) with an extra U(1) gauge symmetry and four extra Higgs singlets (S, S1, S2, and S3) [25]
We have studied the properties of the lightest neutralino in a supersymmetric U(1)′ model with a secluded U(1)′ breaking sector [25]
Summary
Recent mapping of the Cosmic Microwave Background (CMB) anisotropy [1] has provided precision information on the densities of matter and dark energy in the Universe. A natural extension of the MSSM that avoids the above difficulties is a supersymmetric U(1)′ model, with Higgs singlets to break the additional Abelian symmetry spontaneously at the TeV scale. In this letter we investigate the properties of the lightest neutralino and evaluate its relic density in an extended model of the MSSM with an extra U(1) gauge symmetry and four extra Higgs singlets (S, S1, S2, and S3) [25]. When the singlino component is introduced into the neutralino sector, the Zχ0χ0 coupling can be enhanced to give sufficiently large χ0χ0 annihilation This Z-resonance annihilation alone, with suitable parameter values, can reproduce the acceptable cold dark matter relic density in most of the allowed χ0 mass range in the S-model
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