Measurement of $CP$ observables in $B^{\pm }\to D^{(\ast )}{K}^{\pm }$ and $B^{\pm }\to D^{(\ast )}\ddot{I}{€}^{\pm }$ decays

Abstract

Measurements of $CP$ observables in $B^{\pm }\to D^{(\ast )}{K}^{\pm }$ and $B^{\pm }\to D^{(\ast )}\ddot{I}{€}^{\pm }$ decays are presented, where $D^{(\ast )}$ indicates a neutral $D$ or $D^{\ast }$ meson that is an admixture of $D^{(\ast )0}$ and ${\bar{D}}^{(\ast )0}$ states. Decays of the $D^{\ast }$ meson to the $D\ddot{I}{€}^0$ and $D{\hat{I}}^3$ final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the $B$ candidate invariant mass distribution. Decays of the $D$ meson are fully reconstructed in the $K^{\pm }\ddot{I}{€}^{\mp }$, $K^{+}{K}^{-}$ and $\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ final states. The analysis uses a sample of charged $B$ mesons produced in $pp$ collisions collected by the LHCb experiment, corresponding to an integrated luminosity of 2.0, 1.0 and 2.0 fb${}^{-1}$ taken at centre-of-mass energies of $\sqrt{s}$ = 7, 8 and 13 TeV, respectively. The study of $B^{\pm }\to D^{\ast }{K}^{\pm }$ and $B^{\pm }\to D^{\ast }\ddot{I}{€}^{\pm }$ decays using a partial reconstruction method is the first of its kind, while the measurement of $B^{\pm }\to D{K}^{\pm }$ and $B^{\pm }\to D\ddot{I}{€}^{\pm }$ decays is an update of previous LHCb measurements. The $B^{\pm }\to D{K}^{\pm }$ results are the most precise 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-2017-021.html