Productions of and in and decays
Ming-Zhu Liu (School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China, Frontiers Science Center for Rare isotopes, Lanzhou University, Lanzhou 730000, China); Xi-Zhe Ling (Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China); Li-Sheng Geng (School of Physics, Beihang University, Beijing 102206, China, Beijing Key Laboratory of Advanced Nuclear Materials and Physics, Beihang University, Beijing 102206, China, Peng Huanwu Collaborative Center for Research and Education, Beihang University, Beijing 100191, China, Southern Center for Nuclear-Science Theory (SCNT), Institute of Modern Physics, Chinese Academy of Sciences, Huizhou 516000, China)
The two excited vector charmonium states and are difficult to understand as pure charmonium states. Since they are located close to the mass thresholds of and , they can be viewed as and molecules. Furthermore, recent studies indicate that the exotic states and are the isoscalar/isovector and isoscalar/isovector molecules, respectively. In this work, in the molecular picture, we employ the triangle diagram mechanism to study the productions of and in the pionic and radiative decays of , as well as their heavy-quark spin symmetry partners—i.e., the productions of and in the pionic and radiative decays of . Using the effective Lagrangian approach, we obtain the ratios of the branching fractions and , almost independent of model parameters, which indicate that the productions of and in the radiative and pionic decays of are likely to be measured in the future. The experimental studies of the predicted decay modes will help to verify the molecular nature of , , and . We hope that the present work can stimulate experimental and further theoretical studies on these decay modes.
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