Measurement of CP Asymmetries in Two-Body B0(s)-Meson Decays to Charged Pions and Kaons

The time-dependent CP asymmetries in B0 → π+ π− and B0s → 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 center-of-mass energies of 7 and 8 TeV. The same data sample is used to measure the time-integrated C P asymmetries in B0 → K+ π− and B0s → π+ K− decays. The results are C_{π+ π−} = −0.34 ± 0.06 ± 0.01, S_{π+ π−} = −0.63 ± 0.05 ± 0.01, C_{K+ K−} = 0.20 ± 0.06 ± 0.02, S_{K+ K−} = 0.18 ± 0.06 ± 0.02, A_{K+ K−}^{Δ Γ} = −0.79 ± 0.07 ± 0.10, A_{CP}^{B0} = −0.084 ± 0.004 ± 0.003, and A_{CP}^{B0s} = 0.213 ± 0.015 ± 0.007, where the first uncertainties are statistical and the second systematic. Evidence for CP violation is found in the B0s → K+ K− decay for the first time.