Measurement of $CP$ asymmetries in two-body $B_{(s)}^0$-meson decays to charged pions and kaons

Abstract

The time-dependent $CP$ asymmetries in $B^0\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}$ and $B_s^0\to K^{+}{K}^{-}$ decays are measured using a data sample of $pp$ collisions corresponding to an integrated luminosity of 3.0 fb${}^{-1}$, collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The same data sample is used to measure the time-integrated $CP$ asymmetries in $B^0\to K^{+}\ddot{I}{€}^{-}$ and $B_s^0\to \ddot{I}{€}^{+}{K}^{-}$ decays. The results are $C_{\ddot{I}{€}^{+}\ddot{I}{€}^{-}}=-0.34\pm 0.06\pm 0.01$, $S_{\ddot{I}{€}^{+}\ddot{I}{€}^{-}}=-0.63\pm 0.05\pm 0.01$, $C_{K^{+}{K}^{-}}=0.20\pm 0.06\pm 0.02$, $S_{K^{+}{K}^{-}}=0.18\pm 0.06\pm 0.02$, $C_{K^{+}{K}^{-}}^{\hat{I}”\hat{I}“}=-0.79\pm 0.07\pm 0.10$, $A_{CP}^{B^0}=-0.084\pm 0.004\pm 0.003$, and $A_{CP}^{B_s^0}=0.213\pm 0.015\pm 0.007$, where the first uncertainties are statistical and the second systematic. Evidence for $CP$ violation is found in the $B_s^0\to K^{+}{K}^{-}$ decay for the first time.

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-2018-006.html