LHCb: Direct CP-asymmetries in $B^0\to K\pi$ and $B_s^0 \to \pi K$ decays at LHCb

The LHCb experiment is designed to perform flavour physics measurements at the Large Hadron Collider. Using a data sample corresponding to an integrated luminosity of 0.35 fb$^{-1}$ collected by LHCb in 2011, we report measurements of the direct CP asymmetries in the $B^0 \to K^+\pi^-$ and $B_s^0 \to \pi^+K^-$ decays. The results obtained represent the first evidence of CP violation in the decays of $B_s^0$ mesons to $K\pi$ pairs with a significance of 3.3$\sigma$. Furthermore, we report the first observation of CP violation in $B^0$ decays at a hadron collider with a significance exceeding 6$\sigma$.