Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
; Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China
; Peking Univ, Dept Phys, Beijing 100871, Peoples R China
We present a possible explanation to the tiny positive cosmological constant under the frame of AdS(5) spacetime embedded by a dS(4) brane. We calculate the dark energy density by summing the zero point energy of massive scalar fields in AdS(5) spacetime. Under the assumption that the radius of AdS(5) spacetime is of the same magnitude as the radius of observable universe, the dark energy density in dS(4) brane is obtained, which is smaller than the observational value. The reasons are also discussed.