Measurements of branching fractions of $Λ_{c}^{+}\toΣ^{0}K_{S}^{0}π^{+}$ and $Λ_{c}^{+}\toΣ^{0}K_{S}^{0}K^{+}$

Abstract

Based on a data sample corresponding to an integrated luminosity of 6.4~fb$^{-1}$ of $e^+e^-$ annihilation and collected with the BESIII detector at 13 center-of-mass energy points ranging between 4.600~GeV and 4.950~GeV, we report the first observation of the singly Cabibbo-suppressed decay $Λ_c^+ \to Σ^0 K_S^0 π^+$ with a statistical significance of 5.9$σ$. The branching fraction is determined to be $\mathcal{B}(Λ_c^+ \to Σ^0 K_S^0 π^+) = (0.58 \pm 0.14_{\rm stat.} \pm 0.04_{\rm syst.}) \times 10^{-3}$. In addition, the decay $Λ_c^+\toΣ^0K_{S}^{0} K^+$ has also been investigated, and the first evidence for this decay is obtained with a statistical significance of 3.7$σ$.

Figures (5)

• Figure 1: The (a) W-exchange diagram, (b) internal $W$-emission diagram, (c) external $W$-emission diagram for $\Lambda_c^+ \to \Sigma^0 K_S^0 \pi^+$ as well as (d) $W$-exchange diagram and (e) internal $W$-emission diagram for $\Lambda_c^+ \to \Sigma^0 K_S^0 K^+$.
• Figure 2: The $M_{\rm BC}$ distributions of the accepted candidates for (a) $\Lambda_c^+\to\Sigma^0K_{S}^{0}\pi^+$ and (b) $\Lambda_c^+\to\Sigma^0K_{S}^{0}K^{+}$. The black points with error bars are data, and the histograms are MC simulated events. The magenta, yellow, cyan, and brown histograms are the signal, peaking backgrounds, $\Lambda_c^+$ backgrounds and combinatorial backgrounds, respectively.
• Figure 3: Results of the fits to the $M_{BC}$ distributions for (a) $\Lambda_c^+\to\Sigma^0K_{S}^{0}\pi^+$ and (b) $\Lambda_c^+\to\Sigma^0K_{S}^{0}K^{+}$ combining 13 energy points. The black points with error bars are data, the blue, yellow, magenta, green, and red solid lines are the total fit, the ARGUS background function ($\Lambda_c^+ \to \Sigma^0 K_S^0 \pi^+$) and the MC background shape ($\Lambda_c^+ \to \Sigma^0 K_S^0 K^+$), the signals, the peaking backgrounds, and the unmatched components, respectively.
• Figure 4: The fit plot of $\Lambda_c^+\to\Sigma^0 K^{*+}$ combining 13 energy points in the $M_{\rm BC}$ signal region (2.282, 2.291) GeV/$c^2$. The black points with error bars are data, and the blue, magenta, yellow, red, and green lines are the total fit, signal, $\Lambda _c^+ \to \Sigma^0 K_S^0 \pi^+$(non-$K^{*+}$) process, unmatched component, and other background, respectively.
• Figure 5: The likelihoods curve of $\Lambda_c^+\to\Sigma^0K^0_SK^+$. The results obtained with and without incorporating the systematic uncertainties are shown in the red solid and blue dashed curves, respectively. The black arrow shows the result corresponding to the 90% C.L.