1. Department of Physics, Nanjing University, Nanjing 210093, China
2. Center for Particle Nuclear Astrophysics, Nanjing 210093, China
3. CCAST (World Laboratory), PO Box 8730, Beijing 100080, China
4. Department of Physics, Nanjing Normal University, Nanjing 210097, China
5. Institute of Theoretical Physics, Academia Sinica, PO Box 2735, Beijing 100080, China