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arXiv · 2202.10736

The pole counting rule and XYZ states

Hao Chen·Hong-Rong Qi
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Abstract

The pole counting rule is a powerful and model-independent method to distinguish a confining state from a hadronic molecule. It has been applied to the explorations of $X(6900)$, $X_1(2900)$ as well as $Z_c(3900)$, $X(3872)$, $X(4660)$, etc.. For $X(6900)$, both a confining state and a molecular state are not excluded, because lacking of enough data. For $X_1(2900)$, the analysis shows that it should be a $\bar{D}_1 K$ molecule, with $J^P=1^-$ and an iso-singlet interpretation is much more favorable. Finally, it is noted that almost all XYZ particles with exotic quantum numbers can be interpreted as hadronic molecules. The $X(3872)$ is, however, more like a charmonium.

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Hao Chen, Hong-Rong Qi. 2022-02-22. The pole counting rule and XYZ states. https://arxiv.org/abs/2202.10736

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