Explore the properties of $\Lambda(1670)$ in the Cabibbo-favored process $\Lambda^+_c \to p K^- \pi^+$ decay

Recently, the Belle and LHCb Collaborations have measured the $\Lambda^+_c \to p K^- \pi^+$ decay and reported the $p K^-$ invariant mass distribution, which shows a clear cusp structure around the $\eta \Lambda$ threshold. In this work, we have analyzed this process by considering the triangle mechanism and the $S$-wave pseudoscalar meson-octet baryon interactions within the chiral unitary approach, which dynamically generate the $\Lambda(1670)$. Our results are in good agreement with the Belle measurements, which implies that the cusp structure around $\eta\Lambda$ threshold could be associated with the $\Lambda(1670)$ with the molecular nature.