Scalar neutrino dark matter in $U(1)_X$SSM

$U(1)_X$SSM is the extension of the minimal supersymmetric standard model(MSSM) and its local gauge group is $SU(3)_C\times SU(2)_L \times U(1)_Y \times U(1)_X$. Compared with MSSM, it has three singlet new Higgs superfields and right handed neutrinos. In the framework of $U(1)_X$SSM, we study the Higgs mass and suppose the lightest CP-even sneutrino as cold dark matter candidate. For the lightest CP-even sneutrino, the relic density and the cross section with nucleon are both researched. In our chosen parameter space, the numerical results show that considering the lightest CP-even sneutrino as cold dark matter the obtained results satisfy the constraints from the relic density and the scattering off nucleon.