Measurement of CP asymmetry in Bs0 → Ds∓ K ± decays

Abstract

We report the measurements of the CP -violating parameters in Bs0 → Ds∓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, AfΔΓ = 0.39 ± 0.28 ± 0.15, Af=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 Bs0 mixing phase, −2βs, to obtain a measurement of the CKM angle γ from Bs0 → Ds∓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.