Measurement of the branching fractions of the decays $\Lambda_{c}^{+}\rightarrow\Lambda K_{S}^{0}K^{+}$, $\Lambda_{c}^{+}\rightarrow\Lambda K_{S}^{0}\pi^{+}$ and $\Lambda_{c}^{+}\rightarrow\Lambda K^{*+}$

TL;DR

This paper reports the first observation and precise measurement of the branching fractions for specific $\Lambda_{c}^{+} ightarrow ext{decays}$, including evidence of a $K^{*+}$ contribution, using $e^{+}e^{-}$ collision data from BESIII.

Contribution

It provides the first observation of $\Lambda_{c}^{+} ightarrow ext{}\Lambda K_{S}^{0}\pi^{+}$ decay and the most precise measurements of these branching fractions to date.

Findings

First observation of $\Lambda_{c}^{+} ightarrow ext{}\Lambda K_{S}^{0}\pi^{+}$ decay.

Measured branching fractions with high precision: $(3.04 ext{ exttimes}10^{-3})$ and $(1.73 ext{ exttimes}10^{-3})$.

Evidence of $K^{*+}$ contribution with $4.7σ$ significance.

Abstract

Studies are performed of the Cabibbo-favored decay $\Lambda_{c}^{+}\to\Lambda K_{S}^{0}K^+$ and the singly Cabibbo-suppressed decay $\Lambda_{c}^{+}\to\Lambda K_{S}^{0}\pi^+$, based on a sample of $e^{+}e^{-}$ collision data, corresponding to an integrated luminosity of 4.5 fb$^{-1}$, accumulated at center-of-mass energies between $4599.53$ MeV and $4698.82$ MeV with the BESIII detector. The decay $\Lambda_{c}^{+}\to\Lambda K_{S}^{0}\pi^+$ is observed for the first time. The branching fractions of $\Lambda_{c}^{+}\to\Lambda K_{S}^{0}K^+$ and $\Lambda_{c}^{+}\to\Lambda K_{S}^{0}\pi^+$ are measured to be $(3.04\pm0.30\pm0.16)\times 10^{-3}$ and $(1.73\pm0.27\pm0.10)\times 10^{-3}$, respectively, where the first uncertainties are statistical and the second are systematic. These results correspond to the most precise measurement of these quantities for both decays. Evidence of a $K^{*+}$ contribution in the $\Lambda_{c}^{+}\to\Lambda K_{S}^{0}\pi^+$ decay is found with a statistical significance of $4.7\sigma$. The branching fraction of $\Lambda_{c}^{+}\to\Lambda K^{*+}$ is calculated under three possible interference scenarios.