ZBL portal dark matter and LHC Run-2 results

We consider a concise dark matter scenario in the minimal gauged B - L extension of the standard model (SM), where the global B L (baryon number minus lepton number) symmetry in the SM is gauged, and three generations of right-handed neutrinos and a B - L Higgs field are introduced. Associated with the B L gauge symmetry breaking by a VEV of the B L Higgs field, the seesaw mechanism for generating the neutrino mass is automatically implemented after the electroweak symmetry breaking in the SM. In this model context, we introduce a Z(2)-parity and assign an odd parity for one right-handed neutrino while even parities for the other fields. The re fore, the dark mattcr candidate is identified as the right-handed Majorana neutrino with odd Z(2), parity, keeping the minimality of the particle content intact. When the dark matter particle communicates with the SIVI particles mainly through the B L gauge boson (Z' boson), its relic abundance is determined by only three free parameters, the B L gauge coupling (aBL), the Z boson mass (mz,) and the dark matter mass (mDm). With the cosmological upper bound on the dark matter relic abundance we find a lower bound on aBL as a function of mz. On the other hand, we interpret the recent LHC Run -2 results on search for Z' boson resonance to an upper hound on aBL as a function of m7,. Combining the two results we identify an allowed parameter region for this "Z(BL) portal" dark matter scenario, which turns out to be a narrow window with the lower mass bound of m(z)' > 2.5 TeV.