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

Abstract

We study the

reaction by looking at the

$$\pi ^+ \Lambda $$ π + Λ

mass distribution at low energies, in search of signals for the low lying

$$\Sigma ^*$$ Σ ∗

excited states. Apart from a clear signal of the

$$\Sigma (1385) (3/2^+)$$ Σ ( 1385 ) ( 3 / 2 + )

state, we find a smaller peak for the predicted

$$\Sigma (1430) (1/2^-)$$ Σ ( 1430 ) ( 1 / 2 - )

, which has already been confirmed by the Belle Collaboration. A first analysis, considering only the

$$\pi \Lambda $$ π Λ

interaction, shows that the low energy part of the spectrum is better reproduced including contributions from the

$$\Sigma (1430)$$ Σ ( 1430 )

and the predicted

$$\Sigma (1380)(1/2^-)$$ Σ ( 1380 ) ( 1 / 2 - )

state that has been claimed before from analyses of different experiments. However, when we consider the

$$\pi \bar{\Sigma }$$ π Σ ¯

interaction the need for the

$$\Sigma (1380)$$ Σ ( 1380 )

disappears.