Identifying $Σ(1380)$ and $Σ(1430)$ in the $J/ψ\to Λπ\barΣ$ reaction

Abstract

We study the $J/ψ\to Λπ\barΣ$ reaction by looking at the $π^+ Λ$ mass distribution at low energies, in search of signals for the low lying $Σ^+$ states. Apart from a clear signal of the $Σ(1385) (3/2^+)$ state, we find a smaller peak for the predicted $Σ(1430) (1/2^-)$, which has already been confirmed by the Belle Collaboration. A first analysis, considering only the $πΛ$ interaction, shows that the low energy part of the spectrum is better reproduced including contributions from the $Σ(1430)$ and the predicted $Σ(1380)(1/2^-)$ state that has been claimed before from analyses of different experiments. However, when we consider the $π\barΣ$ interaction the need for the $Σ(1380)$ disappears.