Measurement of the CKM angle ${\hat{I}}^3$ using the $B^{\pm }\to D^{\ast }{h}^{\pm }$ channels

Abstract

A measurement of the $CP$-violating observables from $B^{\pm }\to D^{\ast }{K}^{\pm }$ and $B^{\pm }\to D^{\ast }\ddot{I}{€}^{\pm }$ decays is presented, where $D^{\ast }(D)$ is an admixture of $D^{\ast 0}$ and ${\bar{D}}^{\ast 0}$ ($D^0$ and ${\bar{D}}^0$) states and is reconstructed through the decay chains $D^{\ast }\to D\ddot{I}{€}^0/{\hat{I}}^3$ and $D\to K_S^0\ddot{I}{€}^{+}\ddot{I}{€}^{-}/K_S^0{K}^{+}{K}^{-}$. The measurement is performed by analysing the signal yield variation across the $D$ decay phase space and is independent of any amplitude model. The data sample used was collected by the LHCb experiment in proton-proton collisions and corresponds to a total integrated luminosity of 9 fb${}^{-1}$ at centre-of-mass energies of 7, 8 and 13 TeV. The CKM angle ${\hat{I}}^3$ is determined to be $(69_{-14}^{+13}{)}^{\circ }$ using the measured $CP$-violating observables. The hadronic parameters $r_B^{D^{\ast }{K}^{\pm }},r_B^{D^{\ast }\ddot{I}{€}^{\pm }},\hat{I}{´}_B^{D^{\ast }{K}^{\pm }},\hat{I}{´}_B^{D^{\ast }\ddot{I}{€}^{\pm }}$, which are the ratios and strong phase differences between favoured and suppressed $B^{\pm }$ decays, are also reported.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-012.html (LHCb public pages)