Observation of $B_c^{+}\to J/\ddot{I}ˆD^{(\ast )}{K}^{(\ast )}$ decays

Abstract

A search for the decays $B_c^{+}\to J/\ddot{I}ˆD^{(\ast )0}{K}^{+}$ and $B_c^{+}\to J/\ddot{I}ˆD^{(\ast )+}{K}^{\ast 0}$ is performed with data collected at the LHCb experiment corresponding to an integrated luminosity of 3 fb${}^{-1}$. The decays $B_c^{+}\to J/\ddot{I}ˆD^0{K}^{+}$ and $B_c^{+}\to J/\ddot{I}ˆD^{\ast 0}{K}^{+}$ are observed for the first time, while first evidence is reported for the $B_c^{+}\to J/\ddot{I}ˆD^{\ast +}{K}^{\ast 0}$ and $B_c^{+}\to J/\ddot{I}ˆD^{+}{K}^{\ast 0}$ decays. The branching fractions of these decays are determined relative to the $B_c^{+}\to J/\ddot{I}ˆ\ddot{I}{€}^{+}$ decay. The $B_c^{+}$ mass is measured, using the $J/\ddot{I}ˆD^0{K}^{+}$ final state, to be $6274.28\pm 1.40(stat)\pm 0.32(syst)$ MeV/$c^2$. This is the most precise single measurement of the $B_c^{+}$ mass to date.

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-2016-055.html