Observation of the ${\Lambda }_b^0\to {\Lambda }_c^{+}{K}^{+}{K}^{-}\ddot{I}{€}^{-}$ decay

Abstract

The ${\Lambda }_b^0\to {\Lambda }_c^{+}{K}^{+}{K}^{-}\ddot{I}{€}^{-}$ decay is observed for the first time using a data sample of proton-proton collisions at centre-of-mass energies of $\sqrt{s}=7$ and 8 $\mathrm{TeV}$ collected by the $\mbox{LHCb}$ detector, corresponding to an integrated luminosity of $3{\mathrm{fb}}^{-1}$. The ratio of branching fractions between the ${\Lambda }_b^0\to {\Lambda }_c^{+}{K}^{+}{K}^{-}\ddot{I}{€}^{-}$ and the ${\Lambda }_b^0\to {\Lambda }_c^{+}{D}_s^{-}$ decays is measured to be \begin{equation*} \frac{\mathcal{B} ( \varLambda^0_b \to \varLambda^+_c K^+ K^- π^-) } {\mathcal{B} ( \varLambda^0_b \to \varLambda^+_c D^-_s)} = (9.26 \pm 0.29 \pm 0.46 \pm 0.26)\times10^{-2}, \end{equation*} where the first uncertainty is statistical, the second systematic and the third is due to the knowledge of the $D_s^{-}\to K^{+}{K}^{-}\ddot{I}{€}^{-}$ branching fraction. No structure on the invariant mass distribution of the ${\Lambda }_c^{+}{K}^{+}$ system is found, consistent with no open-charm pentaquark signature.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2020-028.html