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 Z₂-parity and assign an odd parity for one right-handed neutrino while even parities for the other fields. Therefore, the dark matter candidate is identified as the right-handed Majorana neutrino with odd Z₂ parity, keeping the minimality of the particle content intact. When the dark matter particle communicates with the SM particles mainly through the B -L gauge boson (Z_B^{L '} boson), its relic abundance is determined by only three free parameters, the B -L gauge coupling (α_{B L}), the Z_B^{L '} boson mass (m_Z^') and the dark matter mass (m_DM). With the cosmological upper bound on the dark matter relic abundance we find a lower bound on α_{B L} as a function of m_Z^'. On the other hand, we interpret the recent LHC Run-2 results on search for Z^' boson resonance to an upper bound on α_{B L} as a function of m_Z^'. Combining the two results we identify an allowed parameter region for this "Z_B^{L '} portal" dark matter scenario, which turns out to be a narrow window with the lower mass bound of m_Z^'>2.5 TeV .