Recently the observation of a new pentaquark state, the hidden-charmed strange $P_{cs}(4459{)}^0$, was reported by the LHCb Collaboration. The spin-parity quantum numbers of this state were not determined as a result of insufficient statistics. To shed light on its quantum numbers, we investigate its decay, $P_{cs}(4459{)}^0\to J/\psi \mathrm{\Lambda }$, the mode that this state has been observed, within the QCD sum rule framework. We obtain the width of this decay assigning the spin-parity quantum numbers of the $P_{cs}(4459{)}^0$ state as $J^P={\frac{1}{2}}^{-}$ and its substructure as diquark-diquark-antiquark. To this end, we first calculate the strong coupling constants defining the considered decay and then use them in the width calculations. The obtained width is consistent with the experimental observation, confirming the quantum numbers $J^P={\frac{1}{2}}^{-}$ and compact pentaquark nature for the $P_{cs}(4459{)}^0$ state.

• Received 23 February 2021
• Accepted 20 April 2021

DOI:https://doi.org/10.1103/PhysRevD.103.094033

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Published by the American Physical Society