Pole analysis on the hadron spectroscopy of $Λ_b\to J/Ψp K^-$

In this paper we study the $J/Ψp$ spectroscopy in the process of $Λ_b\to J/Ψp K^-$. The final state interactions of coupled channel $J/Ψp$ ~-~ $\bar{D} Σ_c$~-~$\bar{D}^{*} Σ_c$ are constructed based on K-matrix with the Chew-Mandelstam function. We build the $Λ_b\to J/Ψp K^-$ amplitude according to the Au-Morgan-Pennington method. The event shape is fitted and the decay width of $Λ_b\to J/Ψp K^-$ is used to constrain the parameters, too. With the amplitudes we extract out the poles and their residues. Our amplitude and pole analysis suggest that the $P_c(4312)$ should be $\bar{D}Σ_c$ molecule, the $P_c(4440)$ could be an S-wave compact pentaquark state, and the structure around $P_c(4457)$ is caused by the cusp effect. The future experimental measurement of the decays of $Λ_b\to \bar{D}Σ_c K^-$ and $Λ_b\to \bar{D}^*Σ_c K^-$ would further help to study the nature of these resonances.

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