Measurement of the branching fractions of the decays ${\Lambda }_c^{+}\to \Lambda K_S^0{K}^{+}$, ${\Lambda }_c^{+}\to \Lambda K_S^0{\pi }^{+}$ and ${\Lambda }_c^{+}\to \Lambda K^{\ast +}$

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 $(3.04\pm 0.30\pm 0.16)\times 10^{-3}$ and $(1.73\pm 0.27\pm 0.10)\times 10^{-3}$, 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 $K^{\ast +}$ 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 ${\Lambda }_c^{+}\to \Lambda K^{\ast +}$ is calculated under three possible interference scenarios.

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Cited by in corpus (2)

• Study ${\Xi }_c^{+}\to \Lambda {\bar{K}}^0{\pi }^{+}$ and search for the low-lying baryons $\Xi (1/2^{-})$ and $\Sigma (1/2^{-})$
• Search for the low-lying excited baryon ${\Sigma }^{\ast }(1/2^{-})$ through process ${\Lambda }_c^{+}\to \Lambda K^0{\pi }^{+}$