Observation of the decay $B_s^0\to \hat{I}{\cdot }_c\ddot{I}•$ and evidence for $B_s^0\to \hat{I}{\cdot }_c\ddot{I}{€}^{+}\ddot{I}{€}^{-}$

Abstract

A study of $B_s^0\to \hat{I}{\cdot }_c\ddot{I}•$ and $B_s^0\to \hat{I}{\cdot }_c\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ decays is performed using $pp$ collision data corresponding to an integrated luminosity of 3.0$\mathrm{f}{\mathrm{b}}^{-1}$, collected with the LHCb detector in Run~1 of the LHC. The observation of the decay $B_s^0\to \hat{I}{\cdot }_c\ddot{I}•$ is reported, where the $\hat{I}{\cdot }_c$ meson is reconstructed in the $p\bar{p}$, $K^{+}{K}^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{-}$, $\ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ and $K^{+}{K}^{-}{K}^{+}{K}^{-}$ decay modes and the $\ddot{I}•(1020)$ in the $K^{+}{K}^{-}$ decay mode. The decay $B_s^0\to J/\ddot{I}ˆ\ddot{I}•$ is used as a normalisation channel. Evidence is also reported for the decay $B_s^0\to \hat{I}{\cdot }_c\ddot{I}{€}^{+}\ddot{I}{€}^{-}$, where the $\hat{I}{\cdot }_c$ meson is reconstructed in the $p\bar{p}$ decay mode, using the decay $B_s^0\to J/\ddot{I}ˆ\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ as a normalisation channel. The measured branching fractions are \begin{eqnarray*} {\mathcal B (B^{0}_{s} \to η_{c} ϕ)} &=& \left(5.01 \pm 0.53 \pm 0.27 \pm 0.63 \right) \times 10^{-4} \,, \nonumber \\ {\mathcal B (B^{0}_{s} \to η_{c} π^+ π^-)} &=& \left(1.76 \pm 0.59 \pm 0.12 \pm 0.29 \right) \times 10^{-4} \,, \end{eqnarray*} where in each case the first uncertainty is statistical, the second systematic and the third uncertainty is due to the limited knowledge of the external branching fractions.

30 pages, 9 figures All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-056.html