The $U{(1)}_X$ extension of the minimal supersymmetric standard model (MSSM) is called as $U{(1)}_X$SSM with the local gauge group $SU{(3)}_C\times SU{(2)}_L\times U{(1)}_Y\times U{(1)}_X$. $U{(1)}_X$SSM has three singlet Higgs superfields beyond MSSM. In $U{(1)}_X$SSM, the mass matrix of neutralino is $8\times 8$, whose lightest mass eigenstate possesses cold dark matter characteristic. Supposing the lightest neutralino as dark matter candidate, we study the relic density. For dark matter scattering off nucleus, the cross sections including spin-independent and spin-dependent are both researched. In our numerical results, some parameter space can satisfy the constraints from the relic density and the experiments of dark matter direct detection.

这 $你{(1)}_X$ 最小超对称标准模型（MSSM）的扩展称为 $你{(1)}_X$SSM 与本地仪表组 $秒你{(3)}_C\times 秒你{(2)}_{升}\times 你{(1)}_{是}\times 你{(1)}_X$. $你{(1)}_X$SSM 拥有超过 MSSM 的三个单线态希格斯超场。在$你{(1)}_X$SSM，中性粒子的质量矩阵为 $8\times 8$，其质量最轻的本征态具有冷暗物质特性。假设最轻的中性粒子作为暗物质候选者，我们研究了遗迹密度。对于从原子核散射的暗物质，研究了自旋无关和自旋相关的截面。在我们的数值结果中，一些参数空间可以满足来自遗迹密度和暗物质直接探测实验的约束。