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Study of $Λ_b\to Λ(ϕ,η^{(\prime)})$ and $Λ_b\to ΛK^+K^-$ decays

We study the charmless two-body $Λ_b\to Λ(ϕ,η^{(\prime)})$ and three-body $Λ_b\to ΛK^+K^- $ decays. We obtain ${\cal B}(Λ_b\to Λϕ)=(3.53\pm 0.24)\times 10^{-6}$ to agree with the recent LHCb measurement. However, we find that ${\cal B}(Λ_b\to Λ(ϕ\to)K^+ K^-)=(1.71\pm 0.12)\times 10^{-6}$ is unable to explain the LHCb observation of ${\cal B}(Λ_b\toΛK^+ K^-)=(15.9\pm 1.2\pm 1.2\pm 2.0)\times 10^{-6}$, which implies the possibility for other contributions, such as that from the resonant $Λ_b\to K^- N^*,\,N^*\toΛK^+$ decay with $N^*$ as a higher-wave baryon state. For $Λ_b\to Λη^{(\prime)}$, we show that ${\cal B}(Λ_b\to Λη,\,Λη^\prime)= (1.47\pm 0.35,1.83\pm 0.58)\times 10^{-6}$, which are consistent with the current data of $(9.3^{+7.3}_{-5.3},<3.1)\times 10^{-6}$, respectively. Our results also support the relation of ${\cal B}(Λ_b\to Λη) \simeq {\cal B}(Λ_b\toΛη^\prime)$, given by the previous study.