From Eq. (19), one can see that σ ( p ) SI ∝ (sin 2 θ/v ′ ) 2 for a given DM mass m$_{N}$ . Fig. 3 shows the spin-independent cross section of RH neutrino with a proton. The resultant cross section is found to be far below the current limits reported by XENON10 [24] and CDMSII [25]: σ$_{SI}$ ≲ 4 × 10 − 8 − 2 × 10 − 7 pb, for a DM mass of 100 GeV-1 TeV. Future experiments such as XENON1T [26] can reach the cross section predicted in our model. 10 -10 10 -9 10 -8  60  80  100  120  140  160  180  200 p [pb] m$_{N}$ [GeV] FIG. 3: The spin independent scattering cross section with a proton. All parameters are same as those used in the previous section. The upper and lower lines correspond to sin θ = 0 . 7 and 0 . 3, respectively. We have proposed a scenario of the RH neutrino dark matter in the context of the minimal gauged U (1)$_{B}$ − L model. We have introduced a discrete Z$_{2}$ parity in the model, so that one RH neutrino assigned as Z$_{2}$ -odd can be stable and, hence, the DM candidate, while the other two RH neutrinos account for neutrino masses and mixings through the seesaw mechanism. No additional degrees of freedom are necessary to be added. We have evaluated the relic density of the dark matter particle. The dominant annihilation modes are via the Higgs boson exchange processes in the s -channel and thus, our model can be called Higgs portal DM model. It has been found that the relic density consistent with the current observation IV. SUMMARY 8