Measurement of CP asymmetry in B_s⁰ → D_s ^∓K^± decays

We report the measurements of the CP -violating parameters in B _s ⁰  → D _s ^∓ K^± decays observed in pp collisions, using a data set corresponding to an integrated luminosity of 3.0 fb⁻¹ recorded with the LHCb detector. We measure C _f = 0.73 ± 0.14 ± 0.05, A _f ^ΔΓ  = 0.39 ± 0.28 ± 0.15, AΔΓf¯¯¯=0.31±0.28±0.15, S _f = −0.52 ± 0.20 ± 0.07, Sf¯¯¯=−0.49±0.20±0.07, where the uncertainties are statistical and systematic, respectively. These parameters are used together with the world-average value of the B _s ⁰ mixing phase, −2β _s , to obtain a measurement of the CKM angle γ from B _s ⁰  → D _s ^∓ K^± decays, yielding γ = (128 _− 22 ^+ 17 )° modulo 180°, where the uncertainty contains both statistical and systematic contributions. This corresponds to 3.8 σ evidence for CP violation in the interference between decay and decay after mixing.