The debate regarding the nature of the three narrow hidden-charm pentaquark states observed by LHCb Collaboration has been intensively discussed since their discovery in the updated analysis of the data. Among the various theoretical interpretations, the hadronic molecular picture is particularly compelling as these three Pc states lie close to the ΣcD̄(∗) thresholds and it successfully describs the J/ψp mass spectrum. However, the model predicts four additional Pc states, based on the heavy quark spin symmetry, which have not been observed experimentally. Moreover, the three narrow Pc states are not seen in other relevant processes. Therefore, clarifying their production mechanism in Λ0b → J/ψp process is crucial for understanding their nature. We propose a novel production mechanism for the three narrow LHCb Pc states. The process proceeds via a Ds1(2860)Λc (2595)D̄ triangle diagram, which generates a triangle singularity near the mass of the Pc(4457), and the three Pc state are dynamically generated. In this mechanism, the J/ψp line shape can be naturally reproduced without introducing free parameters for the weak production vertices or a delicate background.
杜孟林，电子科技大学物理学院教授，2005-2009年就读于武汉大学物理系，2012年硕士毕业于北京大学理论物理专业。2014-2017年于德国波恩大学攻读博士学位，随后分别在德国波恩大学HISKP和西班牙瓦伦西亚大学IFIC做博士后研究，2022年加入电子科技大学物理学院。主要从事理论粒子物理研究，兴趣包括强子物理和强相互作用、粒子物理唯象、以及超出标准模型的新物理。