[1] Natl Heavy Ion Collis, Ctr Theoret Nucl Phys, Lanzhou 730000, Peoples R China
[2] Chinese Acad Sci, Inst Modern Phys, Lanzhou 730000, Peoples R China
[3] Ist Nazl Fis Nucl, Sez Catania, I-95129 Catania, Italy
[4] Lanzhou Univ, Inst Theoret Phys, Lanzhou 730000, Peoples R China