Constraints on the CKM angle ${\hat{I}}^3$ from $B^{\pm }\to D{h}^{\pm }$ decays using $D\to h^{\pm }{h}^{\prime \mp }\ddot{I}{€}^0$ final states

Abstract

A data sample collected with the LHCb detector corresponding to an integrated luminosity of 9 fb${}^{-1}$ is used to measure eleven $CP$ violation observables in $B^{\pm }\to D{h}^{\pm }$ decays, where $h$ is either a kaon or a pion. The neutral $D$ meson decay is reconstructed in the three-body final states: $K^{\pm }\ddot{I}{€}^{\mp }\ddot{I}{€}^0$}; $\ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0$; $K^{+}{K}^{-}\ddot{I}{€}^0$ and the suppressed $\ddot{I}{€}^{\pm }{K}^{\mp }\ddot{I}{€}^0$ combination. The mode where a large $CP$ asymmetry is expected, $B^{\pm }\to [\ddot{I}{€}^{\pm }{K}^{\mp }\ddot{I}{€}^0{]}_D{K}^{\pm }$, is observed with a significance greater than seven standard deviations. The ratio of the partial width of this mode relative to that of the favoured mode, $B^{\pm }\to [K^{\pm }\ddot{I}{€}^{\mp }\ddot{I}{€}^0{]}_D{K}^{\pm }$, is $R_{\mathrm{ADS}(K)}=(1.27\pm 0.16\pm 0.02)\times 10^{-2}$. Evidence for a large $CP$ asymmetry is also seen: $A_{\mathrm{ADS}(K)}=-0.38\pm 0.12\pm 0.02$. Constraints on the CKM angle ${\hat{I}}^3$ are calculated from the eleven reported observables.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-036.html (LHCb public pages)