[1] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
[2] Univ Chinese Acad Sci, Beijing 100049, Peoples R China
[3] Univ Sci & Technol China, Hefei 230026, Peoples R China
[4] INFN, Sez Torino, Via P Giuria 1, I-10125 Turin, Italy
[5] Univ Torino, Dipartimento Fis, Via P Giuria 1, I-10125 Turin, Italy
[6] INFN, Lab Nazl Frascati, Via E Fermi 40, I-00044 Frascati, Italy
[7] INFN, Sez Ferrara, Via G Saragat 1, I-44122 Ferrara, Italy
[8] Univ Ferrara, Dipartimento Fis & Sci Terra, Via G Saragat 1, I-44122 Ferrara, Italy
[9] Univ Piemonte Orientale, Dipartimento Sci & Innovaz Tecnolog, Viale Teresa Michel 11, I-15121 Alessandria, Italy
[10] Chinese Acad Sci, Inst Modern Phys, Lanzhou 730000, Peoples R China
[11] Peking Univ, Beijing 100871, Peoples R China
[12] Indiana Univ, Bloomington, IN 47405 USA
[13] Univ Perugia, Dipartimento Fis & Geol, Via A Pascoli, I-06123 Perugia, Italy