# Observation of a narrow pentaquark state, $P_c(4312)^+$, and of two-peak structure of the $P_c(4450)^+$

## TL;DR

This paper reports the discovery of a new narrow pentaquark state, $P_c(4312)^+$, and confirms the two-peak structure of the $P_c(4450)^+$, providing insights into their decay modes and underlying dynamics.

## Contribution

It presents the first observation of the $P_c(4312)^+$ state and clarifies the structure of the $P_c(4450)^+$ as two overlapping peaks, improving understanding of pentaquark states.

## Key findings

- Discovery of $P_c(4312)^+$ with $7.3\sigma$ significance.
- Confirmation of $P_c(4450)^+$ as two narrow overlapping peaks.
- Proximity to $\\Sigma_c^+\bar{D}^{0}$ and $\\Sigma_c^+\bar{D}^{*0}$ thresholds suggests their role in the states' dynamics.

## Abstract

A narrow pentaquark state, $P_c(4312)^+$, decaying to $J/\psi p$ is discovered with a statistical significance of $7.3\sigma$ in a data sample of ${\Lambda_b^0\to J/\psi p K^-}$ decays which is an order of magnitude larger than that previously analyzed by the LHCb collaboration. The $P_c(4450)^+$ pentaquark structure formerly reported by LHCb is confirmed and observed to consist of two narrow overlapping peaks, $P_c(4440)^+$ and $P_c(4457)^+$, where the statistical significance of this two-peak interpretation is $5.4\sigma$. Proximity of the $\Sigma_c^+\bar{D}^{0}$ and $\Sigma_c^+\bar{D}^{*0}$ thresholds to the observed narrow peaks suggests that they play an important role in the dynamics of these states.