Extra Dimensions and Vacuum Dark Energy Models

The role of vacuum energy or cosmological constant in cosmology is discussed in a kind of nontrivial higher-dimensional model. Under the framework of Einstein's gravity, we obtain the corresponding equations of motion and find that the cosmological constant and vacuum energy in the full regime does not drive its acceleration, but decelerates the expansion of the universe. The dimension of space is required to be n=3 if we regard vacuum energy or cosmological constant as the candidate to drive the accelerated expansion of the universe.