The possible tetraquark states cccc observed by the LHCb experiment  

LHCb实验观测到的可能的四夸克态cccc

作　　者：Kuang-Ta Chaoa Shi-Lin Zhua 赵光达;朱世琳(School of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,Beijing 100871,China;Center of High Energy Physics,Peking University,Beijing 100871,China)

机构地区：[1]School of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,Beijing 100871,China [2]Center of High Energy Physics,Peking University,Beijing 100871,China

出　　处：《Science Bulletin》2020年第23期1952-1953,共2页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China (11975033 and 11745006)。

摘　　要：The molecular positronium (sometimes also denoted as di-positronium) was the multi-electron bound state composed of e+e-e+e-,where the electromagnetic interaction is the underlying driving force.Although its existence was predicted as early as in1947[1],it remained elusive until it was produced experimentally in 2007[2].One may wonder whether there exists the analogue of the di-positronium in Quantum Chromodynamics,which is the tetraquark state with the flavor configurations cccc.Very recently,the LHCb Collaboration observed distinct structures with the cccc (two charm quarks and two anti-charm quarks) in the J/ψ w-pair mass spectrum[3].They reported a broad structure ranging from6.2 to 6.8 GeV and a narrow structure at around 6.9 GeV with a global significance of more than 5r.Let’s denote it as T4c.

关 键 词：force. QUARK POSITRONIUM 

分 类 号：O572.33[理学—粒子物理与原子核物理]