Zooming into CP violation in B ( s ) → hh decays

The LHCb collaboration has recently reported the first observation of CP violation in the penguin-dominated B_s^0 → K − K + decay and further new measurements, indicating differences between the direct CP asymmetries of both the B_s^0 → K − K + , B_d^0 → π − K + and the B_d^0 → π − π + , B_s^0 → K − π + modes. We show that these puzzling differences can be accommodated through sizeable penguin annihilation and exchange topologies in the Standard Model, and constrain them. Utilising the U -spin symmetry, we extract the angle γ of the unitarity triangle from the CP asymmetries in the B_s^0 → K − K + , B_d^0 → π − π + system alone, finding γ =(65_-7^+11)^∘ , in perfect agreement with the determination from tree-level B → DK decays. The B_s^0-B_s^0 mixing phase ϕ s can be extracted from CP violation measurements in B_s^0 → K − K + in a clean way. We present a new strategy and extract ϕ s = −(3 . 6 ± 5 . 4) ° . This result is in agreement with the determination from B_s^0 → J/ψϕ decays. New CP-violating contributions would influence these determinations differently. Hence it is interesting to keep monitoring both as the experimental picture sharpens.