Light neutralino dark matter in U(1) SSM

The $U(1)_X$ extension of the minimal supersymmetric standard model(MSSM) is called as $U(1)_X$SSM with local gauge group $SU(3)_C\times SU(2)_L \times U(1)_Y U(1)_X$. has three singlet Higgs superfields beyond MSSM. In $U(1)_X$SSM, mass matrix neutralino $8\times8$, whose lightest eigenstate possesses cold dark matter characteristic. Supposing candidate, we study relic density. For scattering off nucleus, cross sections including spin-independent and spin-dependent are both researched. our numerical results, some parameter space can satisfy constraints from density experiments direct detection.