Hyperon production in $Λ_c^+\to K^-pπ^+$ and $Λ_c^+\to K^0_Spπ^0 $

Abstract

We investigate $S=-1$ hyperon production from the $Λ_c^+\to K^-pπ^+$ and $Λ_c^+\to K^0_Spπ^0$ decays within the effective Lagrangian approach. We consider the $Σ/Λ$ ground states, $Λ(1520)$, $Λ(1670)(J^p=1/2^-)$, $Λ(1890)(J^p=3/2^+)$; $Λ/Σ$-pole contributions from the combined resonances between 1800 MeV and 2100 MeV; and $N/Δ$-pole and $K^\ast$-pole contributions, which include the proton, $Δ(1232)$, and $K(892)$. We calculate the Dalitz plot density $(d^2Γ/dM_{K^-p}dM_{K^-π^+}$) for the $Λ_c^+\to K^-pπ^+$ decay. The calculated result is in good agreement with experimental data from the Belle Collaboration. Using the parameters from the fit, we present the Dalitz plot density for the $Λ_c^+\to K^0_Spπ^0$ decay. In our calculation, a sharp peak-like structure near 1665 MeV is predicted in the $Λ_c^+\to K^-pπ^+$ decay because of the interference effects between the $Λ(1670)$ resonance and $η$-$Λ$ loop channels. We also demonstrate that we can access direct information regarding the weak couplings of $Λ(1670)$ and $Σ(1670)$ from the $Λ_c^+\to K^0_Spπ^0$ decay. Finally, a possible interpretation for the 1665 MeV structure beyond our prediction is briefly discussed.