We investigate the consequences of heavy quark spin symmetry (HQSS) on hidden-charm pentaquark $P_c$ states. As has been proposed before, assuming the $P_c(4440)$ and the $P_c(4457)$ as $S$-wave ${\overline{D}}^{*}{\mathrm{\Sigma }}_c$ molecules, seven hadronic molecular states composed of $\overline{D}{\mathrm{\Sigma }}_c$, $\overline{D}{\mathrm{\Sigma }}_c^{*}$, ${\overline{D}}^{*}{\mathrm{\Sigma }}_c$, and ${\overline{D}}^{*}{\mathrm{\Sigma }}_c^{*}$ can be obtained, with the $\overline{D}{\mathrm{\Sigma }}_c$ molecule corresponding to the $P_c(4312)$. These seven states can decay into $J/\psi N$ and ${\eta }_{c}N$, and we use HQSS to predict ratios of partial widths of the $S$-wave decays. For the decays into $J/\psi N$, it is found that among all six $P_c$ molecules with spin $1/2$ or $3/2$, at least four states decay much more easily into the $J/\psi N$ than the $P_c(4312)$, and two of them couple dominantly to the ${\overline{D}}^{*}{\mathrm{\Sigma }}_c^{*}$. While no significant peak around the ${\overline{D}}^{*}{\mathrm{\Sigma }}_c^{*}$ threshold is found in the $J/\psi p$ distribution, these higher $P_c$ states either are produced with lower rates or some special production mechanism for the observed $P_c$ states might play an important role, such as an intricate interplay between the production of pentaquarks and triangle singularities.

• Received 11 July 2019

DOI:https://doi.org/10.1103/PhysRevD.100.074007

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Published by the American Physical Society