The $P_{\psi s}^{\Lambda}(4338)$ pentaquark and its partners in the molecular picture

Abstract

The LHCb collaboration has detected a new hidden-charm pentaquark with the quantum numbers of a $\Lambda$ baryon: the $P_{\psi s}^{\Lambda}(4338)$. This pentaquark will be interpreted as a $\bar{D}_s \Lambda_c$-$\bar{D} \Xi_c$ resonance within a contact-range theory. Here we briefly comment on the relation of the new $P_{\psi s}^{\Lambda}(4338)$ with the $P^{\Lambda}_{\psi s}(4459)$. We find that the $P_{\psi s}^{\Lambda}(4338)$ and $P_{\psi s}^{\Lambda}(4459)$ both accept a common description in terms of the same parameters, which predicts the existence of a few additional $P_{\psi}^N$, $P_{\psi s}^{\Lambda}$, $P_{\psi s}^{\Sigma}$ and $P_{\psi s s}^{\Xi}$ molecular pentaquarks composed of a charmed antimeson and an antitriplet charmed baryon. The most robust of these predicted pentaquarks is a $P_{\psi s}^{\Lambda}$ with a mass in the $(4235-4255)\,{\rm MeV}$ range, while other two interesting ones are a $P_{\psi}^{N}(4150)$ and a $P_{\psi}^{\Sigma}(4335)$, the latter basically at the same mass as the $P_{\psi}^{\Lambda}(4338)$, with which it might mix owing to isospin symmetry breaking effects.