Measurement of time-dependent $C\!P$-violating asymmetries in $B^0\to\pi^+\pi^-$ and $B_s^0\to K^+K^-$ decays at LHCb

The $C\!P$-violating asymmetries in the decay and in the interference between mixing and decay in the $B^0\to\pi^+\pi^-$ and $B_s^0\to K^+K^-$ modes are measured using a data sample of $pp$ collisions corresponding to an integrated luminosity of 3 fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Flavour tagging is performed using only a subset of the current available taggers. The results are $C_{\pi^+\pi^-} = -0.24 \pm 0.07 \pm 0.01$, $S_{\pi^+\pi^-} = -0.68 \pm 0.06 \pm 0.01$, $C_{K^+K^-} = 0.24 \pm 0.06 \pm 0.02$, $S_{K^+K^-} = 0.22 \pm 0.06 \pm 0.02$, and $A_{K^+K^-}^{\Delta\Gamma} = -0.75 \pm 0.07 \pm 0.11$, where the first uncertainties are statistical and the second systematic.