Study of ${\Lambda }_b\to \Lambda (\varphi ,{\eta }^{(\prime )})$ and ${\Lambda }_b\to \Lambda K^{+}{K}^{-}$ decays

Abstract

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

Comments: 8 pages, 1 figure, revised version accepted by EPJC