Higgsphobic and fermiophobic Z’ as a single dark matter candidate

A spin-1 Z' particle as a single dark matter candidate is investigated by as- suming 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 ZZZZ and ZZW + W − , which can induce effective ZZq¯ q 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 ZZV V is bounded in the region of 10 −3 ∼ 10 −2 .