Spontaneous Symmetry Breaking Vacuum Energy in Cosmology
  In present paper the gravitational effect of spontaneous symmetry breaking vacuum energy density is investigated by subtracting the flat space-time contribution from the energy in the curved space-time. We found that the remain effective energy-momentum tensor is too small to cause the acceleration of the universe although it satisfies the characteristic of the dark energy. However it could provide a promising explanation to the puzzle why the gravitational effect produced by the huge symmetry breaking vacuum energy in the electroweak theory has not been observed, since it has a sufficient small value (smaller than the observed cosmic energy density by a factor $10^{32}$). 
Kang Zhou, Rui-Hong Yue, Zhan-Ying Yang and De-Cheng Zou
gr-qc hep-th