Investigation of the strange pentaquark candidate $P_{\psi s}^{\Lambda}(4338){}^0$ recently observed by LHCb

Abstract

The recently observed strange pentaquark candidate, $P_{\psi s}^{\Lambda}(4338){}^0$, is investigated to provide information about its nature and substructure. To this end, its mass and width through the decay channels $P_{\psi s}^{\Lambda}(4338){}^0 \rightarrow J/\psi \Lambda$ and $P_{\psi s}^{\Lambda}(4338){}^0 \rightarrow \eta_c \Lambda$ are calculated by applying two- and three-point QCD sum rules, respectively. The state is considered as a $\Xi_c\bar{D}$ meson-baryon molecular structure with spin-parity quantum numbers $J^P=\frac{1}{2}^-$. The obtained mass, $m_{P_{\psi s}^{\Lambda}(4338){}^0}=4338\pm 130~\mathrm{MeV}$, and width, $\Gamma_{P_{\psi s}^{\Lambda}(4338){}^0}= 10.40\pm 1.93~\mathrm{MeV}$, are consistent with the experimental data within the presented uncertainties. This allows us to assign a $\Xi_c\bar{D}$ molecular structure of $J^P=\frac{1}{2}^-$ for the $P_{\psi s}^{\Lambda}(4338){}^0$ state.