Observation of ${\Lambda }_b^0\to {\Lambda }_c^{+}{\bar{D}}^{(\ast )0}{K}^{-}$ and ${\Lambda }_b^0\to {\Lambda }_c^{+}{D}_s^{\ast -}$ decays

Abstract

The decays ${\Lambda }_b^0\to {\Lambda }_c^{+}{\bar{D}}^{(\ast )0}{K}^{-}$ and ${\Lambda }_b^0\to {\Lambda }_c^{+}{D}_s^{\ast -}$ are observed for the first time, in proton-proton collision data at $\sqrt{s}=13$TeV corresponding to an integrated luminosity of 5.4 fb${}^{-1}$ collected with the LHCb detector. Their ratios of branching fractions with respect to the ${\Lambda }_b^0\to {\Lambda }_c^{+}{\mathrm{D}}_s^{-}$ mode are measured to be \begin{align*} \begin{split} \frac{\mathcal{B}(Λ_b^0 \to Λ_c^+\bar{D}^0 K^-)}{\mathcal{B}(Λ_b^0 \to Λ_c^+ D_s^-)} & = 0.1908 {}_{-0.0034}^{+0.0036} {}_{-0.0018}^{+0.0016} \pm 0.0038 \frac{\mathcal{B}(Λ_b^0 \to Λ_c^+\bar{D}^{*0} K^-)}{\mathcal{B}(Λ_b^0 \to Λ_c^+ D_s^-)} & = 0.589 {}_{-0.017}^{+0.018} {}_{-0.018}^{+0.017} \pm 0.012 \frac{\mathcal{B}(Λ_b^0 \to Λ_c^+ D_s^{*-})}{\mathcal{B}(Λ_b^0 \to Λ_c^+ D_s^-)} & = 1.668 \pm 0.022 {}_{-0.055}^{+0.061}\ , \end{split} \end{align*} where the first uncertainties are statistical, the second systematic, and the third, for the ${\Lambda }_b^0\to {\Lambda }_c^{+}{\bar{D}}^{(\ast )0}{K}^{-}$ decays, are due to the uncertainties on the branching fractions of the $D_s^{-}\to K^{-}{K}^{+}{\pi }^{-}$ and ${\bar{D}}^0\to K^{+}{\pi }^{-}$ decay modes. The measured branching fractions probe factorization assumptions in effective theories and provide the normalization for future pentaquark searches in ${\Lambda }_b^0\to {\Lambda }_c^{+}{\bar{D}}^{(\ast )0}{K}^{-}$ decay channels.

All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-034.html (LHCb public pages); v2 after journal review

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Cited by in corpus (1)

• First observation of the ${\Lambda }_b^0\to {\Lambda }_c^{+}{D}_s^{-}{K}^{+}{K}^{-}$ decay and search for pentaquarks in the ${\Lambda }_c^{+}{D}_s^{-}$ system