The Ωc → π⁺ \, (π⁰,\, η)\, π Ξ^* reactions and the two Ξ(1820) states

We have studied the Ωc → π⁺ (π⁰, η) π Ξ^* decays, where the final π Ξ^* comes from the decay of two resonances around the nominal Ξ(1820), which are generated from the interaction of coupled channels made of a pseudoscalar and a baryon of the decuplet. The π Ξ^* mass distributions obtained in the six different reactions studied are quite different and we single out four of them, which are free of a tree level contribution, showing more clearly the effect of the resonances. The lower mass resonance is clearly seen as a sharp peak, but the higher mass resonance manifests itself through an interference with the lower one that leads to a dip in the mass distribution around 1850 \, MeV. Such a feature is similar to the dip observed in the s-wave π π cross section around the 980 \, MeV coming from the interference of the f₀(500) and f₀(980) resonances. Its observation in coming upgrades of present facilities will shed light on the existence of these two resonances and their nature.