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

We report on measurements of the time-dependent CP violating observables in Bs0 → Ds∓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, AfΔΓ = 0.37 ± 0.42 ± 0.20, Af¯ΔΓ=0.20±0.41±0.20\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {A}_{\overline{f}}^{\varDelta \varGamma }=0.20\pm 0.41\pm 0.20 $$\end{document}, Sf = −1.09±0.33±0.08, Sf¯=−0.36±0.34±0.08\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {S}_{\overline{f}}=-0.36\pm 0.34\pm 0.08 $$\end{document}, where the uncertainties are statistical and systematic, respectively. Using these observables together with a recent measurement of the Bs0 mixing phase −2βs leads to the first extraction of the CKM angle γ from Bs0 → Ds∓K± decays, finding γ = (115− 43+ 28)° modulo 180° at 68% CL, where the error contains both statistical and systematic uncertainties. [graphic not available: see fulltext]