Measurement of CP asymmetry in B-s(0) -> D-s(-/+) K--/+ decays

Abstract

We report on measurements of the time-dependent CP violating observables in B0 s → D∓ s K± decays using a dataset corresponding to 1.0 fb−1 of pp collisions recorded with the LHCb detector. We find the CP violating observables Cf = 0.53±0.25±0.04, A∆Γ f = 0.37 ± 0.42 ± 0.20, A∆Γ f = 0.20 ± 0.41 ± 0.20, Sf = −1.09 ± 0.33 ± 0.08, Sf = −0.36 ± 0.34 ± 0.08, where the uncertainties are statistical and systematic, respectively. Using these observables together with a recent measurement of the B0 s mixing phase −2βs leads to the first extraction of the CKM angle γ from B0 s → D∓ s K± decays, finding γ = (115+28 −43) ◦ modulo 180◦ at 68% CL, where the error contains both statistical and systematic uncertainties.