Evidence supporting the existence of $P_c(4380)^{\pm}$ from the recent measurements of $B_s \to J/\psi p\bar{p}$

TL;DR

This paper presents evidence supporting the existence of the pentaquark state $P_c(4380)$ from recent LHCb measurements of $B_s o J/ par{p}$, suggesting a possible resonance near 4.34 GeV.

Contribution

The study provides the first combined analysis linking the $J/ p$ structure near 4.34 GeV to the $P_c(4380)^+$ state, supporting its existence with specific spin-parity assumptions.

Findings

Evidence of a $J/ p$ structure near 4.34 GeV in $B_s$ decays.

Possible identification of this structure as the $P_c(4380)^+$ pentaquark.

Support for the $J^{P}=3/2^{-}$ assignment consistent with molecular state models.

Abstract

Very recently, the LHCb collaboration released the newest measurements of $B_s \to J/\psi p\bar{p}$, where an enhancement structure near 4.34 GeV was observed in the invariant mass spectrum of $J/\psi p$ with the statistical significance of $3.1-3.7$ $\sigma$. In this work, by performing a combined analysis for the three invariant mass spectra of $B_s \to J/\psi p\bar{p}$, we find that this $J/\psi p$ structure near 4.34 GeV can correspond to the contributions from the $P_c(4380)^+$ state with the assumption of $J^{P}=3/2^{-}$ together with the reflections of $B_s \to (f_2^{*} \to p\bar{p})J/\psi$. Here, $P_c(4380)$ was first observed in $\Lambda_b \to J/\psi p K$ but not confirmed in the updated LHCb data in 2019, and $f_2^{*}$ means the exciting light isoscalar tensor meson around 2.0 GeV. Thus, this provides a possible evidence to support the existence of the pentaquark $P_c(4380)$. Specifically, the assumed spin parity $J^{P}=3/2^{-}$ of $P_c(4380)$ is consistent with a prediction of the theoretical explanation of an $S$-wave $\bar{D}\Sigma_c^*$ molecular bound state.