Study of a WIMP dark matter model with the updated results of CDMS II

The new observation of CDMS II favors low mass WIMPs. Taking the CDMS II new results as input, we consider a standard model (SM) singlet: the darkon as the dark matter (DM) candidate, which can be either a scalar, fermion, or vector. It is found that the simplest scenario of DM +SM conflicts with the stringent constraint set by the LHC data. New physics beyond the SM is needed, and in this work, we discuss an extended standard model S_{UL(2)⊗UY(1)⊗U(1)^' where U(1^)' only couples to the darkon. The new gauge symmetry is broken into Uem(1) and two neutral bosons Z⁰ and Z^', which results in mixtures of Wμ3, Bμ}, and X_μ. Following the literature and based on the CDMS data, we conduct a complete analysis to verify the validity of the model. The cross section of the elastic scattering between the darkon and nucleon is calculated, and the DM relic density is evaluated in the extended scenario. It is found that by considering the constraints from both the cosmology and collider experiments, one can reconcile all the presently available data only if Z ' ^{is lighter than Z0.}