Revisiting hidden-charm pentaquarks from QCD sum rules

We revisit the hidden-charm pentaquark states $P_c(4380)$ and $P_c(4450)$ using the method of QCD sum rules by requiring the pole contribution to be larger than or around 30% to better insure the one-pole parametrization to be valid. We find two mixing currents and our results suggest that the $P_c(4380)$ and $P_c(4450)$ can be identified as hidden-charm pentaquark states having $J^P=3\mathrm{/}{2}^{-}$ and $5\mathrm{/}{2}^{+}$, respectively, while there still exist other possible spin-parity assignments, such as $J^P=3\mathrm{/}{2}^{+}$ and $J^P=5\mathrm{/}{2}^{-}$, which needs to be clarified in further theoretical and experimental studies.