Observation of the $\varLambda^0_b \to \varLambda^+_c K^+ K^- \pi^-$ decay

TL;DR

This paper reports the first observation of the decay mode $ extLambda^0_b o extLambda^+_c K^+ K^- extpi^-$ in proton-proton collisions at 7 and 8 TeV, measuring its branching ratio relative to a known decay.

Contribution

It provides the first experimental observation of this decay mode and measures its branching fraction ratio, adding new data to heavy baryon decay studies.

Findings

First observation of the decay mode $ extLambda^0_b o extLambda^+_c K^+ K^- extpi^-$.

Measured branching fraction ratio: (9.26 ± 0.29 ± 0.46 ± 0.26)×10^{-2}.

No evidence of open-charm pentaquark structures in the invariant mass distribution.

Abstract

The $\varLambda^0_b \to \varLambda^+_c K^+ K^- \pi^-$ 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 $\rm{TeV}$ collected by the $\mbox{LHCb}$ detector, corresponding to an integrated luminosity of $3{\rm{fb}^{-1}}$. The ratio of branching fractions between the $\varLambda^0_b \to \varLambda^+_c K^+ K^- \pi^-$ and the $\varLambda^{0}_{b}\to\varLambda^{+}_{c}D^{-}_{s}$ decays is measured to be \begin{equation*} \frac{\mathcal{B} ( \varLambda^0_b \to \varLambda^+_c K^+ K^- \pi^-) } {\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 $D^-_s \to K^+ K^- \pi^-$ branching fraction. No structure on the invariant mass distribution of the $\varLambda^+_c K^+$ system is found, consistent with no open-charm pentaquark signature.