[Chen, Wei] Univ Chinese Acad Sci, Sch Nucl Sci & Technol, Beijing 100049, Peoples R China.^[Cao, Shanshan] Texas A&M Univ, Cyclotron Inst, College Stn, TX 77843 USA.^[Cao, Shanshan] Texas A&M Univ, Dept Phys & Astron, College Stn, TX 77843 USA.^[Cao, Shanshan] Wayne State Univ, Dept Phys & Astron, Detroit, MI 48201 USA.^[Luo, Tan] Univ Santiago de Compostela, Inst Galego Fis Altas Enerxias IGFAE, E-15782 Galicia, Spain.^[Pang, Long-Gang;Wang, Xin-Nian] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.^[Pang, Long-Gang;Wang, Xin-Nian] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.^[Wang, Xin-Nian] Lawrence Berkeley Natl Lab, Nucl Sci Div MS 70R0319, Berkeley, CA 94720 USA.^[Wang, Xin-Nian] Univ Calif Berkeley, Phys Dept, Berkeley, CA 94720 USA.