Two states of the $\Xi(1820)$

We present a new interpretation for the observed $\Xi(1820)$ resonance in the recent BESIII measurement of the $K^- \Lambda$ mass distribution in the $\psi(3686) \to K^- \Lambda \bar\Xi^+$ decay. We recall that the chiral unitary approach for the interaction of pseudoscalar mesons with the baryons of the decuplet predicts two states for the $\Xi(1820)$ resonance, one around 1824 MeV and narrow, and another one around 1875 MeV and wide. We show how the consideration of the two $\Xi(1820)$ states provides a natural explanation to the BESIII data. Furthermore, we propose the reaction $\psi(3686)\to \bar \Xi^+ \bar K^0 \Sigma^{*-} \to \bar \Xi^+ \bar K^0 \pi^- \Lambda$ in order to show evidence for the existence of two $\Xi(1820)$ states. The phase space for $\bar K^0 \Sigma^{*-}$ production reduces the effect of the lower mass resonance, magnifying the effect of the higher mass resonance that shows clearly over the phase space. The proposed reaction is particularly suited to show the effect of the higher $\Xi(1820)$ state. Its observation in coming upgrades of present facilities will shed light on the existence of two $\Xi(1820)$ states and their nature.