Search for hidden-charm pentaquark states in three-body final states

Abstract: The three pentaquark states, $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$, discovered by the LHCb Collaboration in 2019, are widely recognized as $\bar{D}^{(\ast)}\Sigma_{c}$ hadronic molecules. Together with their four $\bar{D}^{(*)}\Sigma_{c}^{\ast}$ partners dictated by heavy quark spin symmetry they present a complete multiplet of hadronic molecules of $\bar{D}^{(\ast)}\Sigma_{c}^{(\ast)}$. It is widely recognized that to understand their nature, other discovery channels play an important role. In this work, we investigate two three-body decay modes of the $\bar{D}^{(\ast)}\Sigma_{c}^{(\ast)}$ molecules. The tree-level modes proceed via off-shell $\Sigma_{c}^{(\ast)}$ baryons, $\bar{D}^{(\ast)}\Sigma_{c}^{(\ast)} \to \bar{D}^{(\ast)}\left(\Sigma_{c}^{(\ast)}\to \Lambda_{c}\pi\right)\to\bar{D}^{(\ast)}\Lambda_{c}\pi$, while the triangle-loop modes proceed through $\bar{D}^{\ast}\Sigma_{c}^{(\ast)}\to J/\psi N\pi$, $\eta_{c}N\pi$ via $\bar{D}\Sigma_{c}^{(\ast)}$ rescattering to $J/\psi N$ and $\eta_{c}N$. Our results indicate that the decay widths of the $P_{c}(4457)$ and $\bar{D}^{(\ast)}\Sigma_{c}^{\ast}$ states into $\bar{D}^{(\ast)}\Lambda_{c}\pi$ are several MeV, as a result can be observed in the upcoming Run 3 and Run 4 of LHC. The partial decay widths into $\bar{D}^{(\ast)}\Lambda_{c}\pi$ of the $P_{c}(4312)$ and $P_{c}(4440)$ states range from tens to hundreds of keV. In addition, the partial decay widths of $\bar{D}^{\ast}\Sigma_{c}$ molecules into $J/\psi N \pi$ and $\eta_c N \pi$ are several keV and tens of keV, respectively, and the partial decay widths of $\bar{D}^{\ast}\Sigma_{c}^{\ast}$ molecules into $J/\psi N \pi$ vary from several keV to tens of keV. These three-body decay modes of the pentaquark states are of great value to further observations of the pentaquark states and to a better understanding of their nature.