Roles of $a_0(980)$, $\Lambda (1670)$, and $\Sigma (1385)$ in the ${\Lambda }_c^{+}\to \eta \Lambda {\pi }^{+}$ decay

Abstract

Recently, the Belle Collaboration has measured the ${\Lambda }_c^{+}\to \eta \Lambda {\pi }^{+}$ decay and reported the $\eta \Lambda$ and $\Lambda {\pi }^{+}$ invariant mass distributions, which show the clear signals of the resonances $\Lambda (1670)$ and $\Sigma (1385)$, respectively. Based on our previous works [Eur. Phys. J. C 76 (2016) 496 and Phys. Rev. D 95 (2017) 074024], we re-analyze this process by considering the $S$-wave $\eta \Lambda$ and $\eta {\pi }^{+}$ final state interactions within the chiral unitary approach, which dynamically generate the $\Lambda (1670)$ and $a_0(980)$, respectively. Our results are in good agreement with the Belle measurements, which supports the molecular nature of the $\Lambda (1670)$ and $a_0(980)$. In addition, the $\eta {\pi }^{+}$ invariant mass distributions are also computed and a cusp structure of $a_0(980)$ is cleary shown around the $K\bar{K}$ mass threshold.

Comments: 8 pages, 9 figures