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'q\bar{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 Z'Z'VV is bounded in the region of 10^{-3}~10^{-2}. 
Nan Chen, Ying Zhang, Qing Wang, Giacomo Cacciapaglia, Aldo Deandrea,   Luca Panizzi
hep-ph astro-ph.HE hep-ex