Measurement of CP asymmetry in Bs 0 → Ds ∓ K ± decays

Abstract

Abstract: We report the measurements of the CP-violating parameters in B0 s → 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 Cf = 0.73 ± 0.14 ± 0.05, A∆Γ f = 0.39 ± 0.28 ± 0.15, A∆Γ f¯ = 0.31 ± 0.28 ± 0.15, Sf = −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 B0 s mixing phase, −2βs, to obtain a measurement of the CKM angle γ from B0 s → D∓ s K± decays, yielding γ = (128 +17 −22) ◦ 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