Observation of the decay $\overline{B_s^0}\to \ddot{I}{‡}_{c2}{K}^{+}{K}^{-}$ in the $\ddot{I}†$ mass region

Abstract

The $\overline{B_s^0}\to \ddot{I}{‡}_{c2}{K}^{+}{K}^{-}$ decay mode is observed and its branching fraction relative to the corresponding $\ddot{I}{‡}_{c1}$ decay mode, in a $\pm 15\text{MeV}/c^2$ window around the $\ddot{I}•$ mass, is found to be $\frac{\mathcal{B}(\overline{B_s^0}\to \ddot{I}{‡}_{c2}{K}^{+}{K}^{-})}{\mathcal{B}(\overline{B_s^0}\to \ddot{I}{‡}_{c1}{K}^{+}{K}^{-})}=(17.1\pm 3.1\pm 0.4\pm 0.9)\%,$ where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the branching fractions of radiative $\ddot{I}{‡}_c$ decays. The decay mode $\overline{B_s^0}\to \ddot{I}{‡}_{c1}{K}^{+}{K}^{-}$ allows the $B_s^0$ mass to be measured as $m(B_s^0)=5366.83\pm 0.25\pm 0.27\text{MeV}/c^2,$ where the first uncertainty is statistical and the second systematic. A combination of this result with other LHCb determinations of the $B_s^0$ mass is made.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2018-018.html