Identifying $\Sigma (1380)$ and $\Sigma (1430)$ in the $J/\psi \to \Lambda \pi \bar{\Sigma }$ reaction

Abstract

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

Comments: 9 pages, 8 figures