We report on measurements of the time-dependent CP violating observables in Bs0DsK± decays using a dataset corresponding to 1.0 fb1 of pp collisions recorded with the LHCb detector. We find the CP violating observables Cf= 0.53±0.25±0.04, Af=0.37±0.42±0.20, $$ {A}_{\overline{f}}^{\varDelta \varGamma }=0.20\pm 0.41\pm 0.20 $$, Sf= 1.09±0.33±0.08, $$ {S}_{\overline{f}}=-0.36\pm 0.34\pm 0.08 $$, where the uncertainties are statistical and systematic, respectively. Using these observables together with a recent measurement of the Bs0mixing phase 2sleads to the first extraction of the CKM angle from Bs0DsK± decays, finding =(11543+28)° modulo 180° at 68% CL, where the error contains both statistical and systematic uncertainties.
