Higgsphobic and fermiophobic Z’ as a single dark matter candidate

A spin-1 Z’ particle as a single dark matter candidate is investigated by assuming that it does not directly couple to the Higgs boson and standard model fermions and does not mix with the photon and Z boson. The remaining dominant vertices are quartic Z ′ Z ′ ZZ and Z ′ Z ′ W + W − , which can induce effective Z^'Z^'qq couplings through standard-model gauge-boson loops. We discuss constraints from the cosmological thermal relic density, and direct and indirect-detection experiments, and find that a dark Z’ can only exist above the W boson mass threshold, and the effective quartic coupling of Z ′ Z ′ VV is bounded in the region of 10 −3 10 −2 .