Search for the low-lying excited baryon $\Sigma^*(1/2^-)$ 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 $\Sigma^*(1/2^-)$, dynamically generated via the $S$-wave pseudoscalar meson-octet baryon interaction, as well as from the intermediate resonances $K^*(892)$ 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 $\Sigma^*(1/2^-)$. 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 $\Sigma^*(1/2^-)$ and advancing our understanding of the light baryon spectrum.