Search for the low-lying excited baryon ${\Sigma }^{\ast }(1/2^{-})$ through process ${\Lambda }_c^{+}\to \Lambda K^0{\pi }^{+}$

Abstract

Motivated by recent BESIII measurements of the singly Cabibbo-suppressed processes ${\Lambda }_c^{+}\to \Lambda K^{+}{\pi }^0$ and ${\Lambda }_c^{+}\to \Lambda K_S^0{\pi }^{+}$, we investigate the process ${\Lambda }_c^{+}\to \Lambda K^0{\pi }^{+}$ by taking into account the contribution from the low-lying excited baryon ${\Sigma }^{\ast }(1/2^{-})$, dynamically generated via the $S$-wave pseudoscalar meson-octet baryon interaction, as well as from the intermediate resonances $K^{\ast }(892)$ and $N(1535)$. Our model successfully reproduces the BESIII ${\pi }^{+}{K}^0$ invariant mass distribution, and predicts a distinct cusp structure around 1.43~GeV in the ${\pi }^{+}\Lambda$ invariant mass distribution, which is associated with the predicted ${\Sigma }^{\ast }(1/2^{-})$. Future high-precise measurements of this process at BESIII, Belle~II, and the proposed Super Tau-Charm Facility experiments will be crucial for testing the existence of ${\Sigma }^{\ast }(1/2^{-})$ and advancing our understanding of the light baryon spectrum.

Comments: 9 pages, 6 figures