[1] Peking Univ, Sch Phys, Beijing 100871, Peoples R China
[2] Peking Univ, State Key Lab Nucl Phys & Technol, Beijing 100871, Peoples R China
[3] Peking Univ, Ctr High Energy Phys, Beijing 100871, Peoples R China
[4] Collaborat Innovat Ctr Quantum Matter, Beijing 100871, Peoples R China
[5] Jefferson Lab, Theory Ctr, 12000 Jefferson Ave, Newport News, VA 23606 USA
[6] Brookhaven Natl Lab, Phys Dept, Upton, NY 11973 USA
[7] SUNY Stony Brook, CN Yang Inst Theoret Phys, Stony Brook, NY 11794 USA
[8] SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA