Dynamical resonances $Λ(1405)$, $Λ(1670)$, and $f_0(980)$ in the process $Λ_c^+ \to p K^+ K^-$

Motivated by new BESIII measurements of the singly Cabibbo-suppressed process $Λ_c^+ \to p K^+ K^-$, we investigate the $Λ_c^+ \to p K^+ K^-$ reaction by taking into account contributions from the low-lying excited baryons $Λ(1405)$ and $Λ(1670)$, which are dynamically generated via the $S$-wave pseudoscalar meson-octet baryon interaction. In addition, contributions from the light scalar mesons $f_0(980)/a_0(980)$ dynamically generated via the $S$-wave pseudoscalar meson-pseudoscalar meson interaction, as well as the vector meson $ϕ(1020)$, are also considered. The theoretical calculations could reproduce the invariant mass distributions of $K^- p$ and $K^+K^-$ measured by the BESIII Collaboration well. Specifically, a near-threshold enhancement and a cusp structure around 1670~MeV in the $pK^-$ invariant mass spectrum are obtained, which are associated with the $Λ(1405)$ and $Λ(1670)$ resonances, respectively. Furthermore, contributions from the scalar meson $f_0(980)$ and vector meson $ϕ(1020)$ are clearly observed in the $K^+ K^-$ invariant mass distribution. Future high-precision measurements by the BESIII, Belle II, and the proposed Super Tau-Charm Facility experiments will substantially deepen our understanding of the intrinsic properties of the low-lying excited $Λ$ states and the $f_0(980)/a_0(980)$ meson.