Search for the Cabibbo-suppressed decays $Λ_c^{+}\toΣ^0K^{+}π^{0}$ and $Λ_c^{+}\toΣ^0K^{+}π^{+}π^{-}$

TL;DR

This study searches for singly Cabibbo-suppressed hadronic decays of the charmed baryon Lambda_c^+ to Sigma^0 plus kaon and pions, using 4.5 fb^-1 of e+e- collision data from BESIII. A single-tag, blinded analysis with detailed event selection and a simultaneous fit across seven energy points yields no significant signal, setting 90% C.L. upper limits on the branching fractions: B(Lambda_c^+ -> Sigma^0 K^+ pi^0) < 5.0e-4 and B(Lambda_c^+ -> Sigma^0 K^+ pi^+ pi^-) < 6.5e-4. The first limit is more stringent than the previous BESIII double-tag result and is compatible with theoretical predictions, while the second limit is less stringent than BaBar's. These measurements refine the understanding of hadronic Lambda_c^+ decays and provide essential input for modeling non-factorizable contributions in charmed-baryon processes; future improvements are expected with larger data samples.

Abstract

Utilizing 4.5 $fb^-$ of $e^+e^-$ annihilation data collected at center-of-mass energies ranging from 4599.53 MeV to 4698.82 MeV by the BESIII detector at the BEPCII collider, we search for the singly Cabibbo-suppressed hadronic decays $Λ_{c}^{+}\toΣ^{0} K^{+}π^{0}$ and $Λ_{c}^{+}\toΣ^{0}K^{+}π^+π^-$ with a single-tag method. No significant signals are observed for both decays. The upper limits on the branching fractions at the $90\%$ confidence level are determined to be $5.0\times 10^{-4}$ for $Λ_{c}^{+}\toΣ^{0} K^{+}π^{0}$ and $6.5\times 10^{-4}$ for $Λ_c^{+}\toΣ^0K^{+}π^{+}π^{-}$.

Figures (6)

• Figure 1: The distributions of $\Delta E_{p\pi^- K^{+}\gamma\gamma} (\Delta E_{p\pi^- K^{+}\pi^+\pi^-})$ for $\Lambda_c^+ \to \Sigma^{0}K^+\pi^{0}$($\Lambda_c^+ \to \Sigma^{0}K^+\pi^{+}\pi^{-}$). The histograms of the signal MC are normalized to make the distribution more intuitive when compared to the inclusive MC.
• Figure 2: Single-tag efficiencies (%) for $\Lambda_c^+ \to \Sigma^{0}K^+\pi^{0}$ and $\Lambda_c^+ \to \Sigma^{0}K^+\pi^+\pi^-$ at different energy points, where the uncertainties are statistical only.
• Figure 3: The contamination rates (%) after including the BFs of the secondary decays at each energy point, where the uncertainties are statistical only.
• Figure 4: The fit to the $M_{\rm BC}$ distributions of $\Lambda_c^+ \to \Sigma^{0}K^+\pi^{0}$(left) and $\Lambda_c^+ \to \Sigma^{0}K^+\pi^+\pi^-$(right) of the combined data. For $\Lambda_c^+ \to \Sigma^{0}K^+\pi^{0}$, the violet histograms are the signal MC samples normalized with a product BF of 1.2 $\times 10^{-3}$Geng:2018upx, the argus function includes seven sub-argus functions. The black point with the error bar is data, the blue solid line represents the total fit function, the gray dashed line shows the combinatorial background, the violet dash line is the signal function, the navy blue dashed line is the un-matched component, cyan dashed line is the background shape extract from $\Lambda_c^{+}\to\Lambda K^{*+}$ MC samples, and red dashed line is the background shape extract from $\Lambda_c^{+}\to\Xi^{0} K^{+}$ MC samples.
• Figure 5: Multiplicative systematic uncertainties in unit of % for the BF measurement.