# Molecular Interpretation of the $P_c(4440)$ and $P_c(4457)$ States

## TL;DR

This paper proposes a molecular model for the $P_c(4440)$ and $P_c(4457)$ states, explaining their quantum numbers, widths, and production rates through pion-exchange dynamics and novel channel coupling.

## Contribution

The model introduces the $ ext{Lambda}_c(2595)ar D$ channel and explains both states' properties without extra short-range interactions.

## Key findings

- Predicts quantum numbers $J^P(4457)=1/2^+$ and $J^P(4440)=3/2^-$.
- Accounts for the relative widths of the states.
- Explains production rates in $ ext{Lambda}_b$ decays with new channel considerations.

## Abstract

A molecular model of the $P_c(4457)$ and $P_c(4440)$ LHCb states is proposed. The model relies on channels coupled by long range pion-exchange dynamics with features that depend crucially on the novel addition of the $\Lambda_c(2595)\bar D$ channel. A striking prediction of the model is the unusual combination of quantum numbers $J^P(4457) = 1/2^+$ and $J^P(4440) = 3/2^-$. Unlike in other models, a simultaneous description of both states is achieved without introducing additional short-range interactions. The model also gives a natural explanation for the relative widths of the states. We show that the usual molecular scenarios cannot explain the production rate of $P_c$ states in $\Lambda_b$ decays, and that this can be resolved by including $\Lambda_c(2595)\bar D$ and related channels. Experimental tests and other states are discussed in the conclusions.