First observation of CP violation in the decays of Bs0 mesons

Abstract

Using pp collision data corresponding to an integrated luminosity of 1.0 fb-1 and collected by LHCb in 2011 at a center-of-mass energy of 7 TeV, we report the measurement of direct CP violation in Bs0→K -π+ decays, ACP(Bs0→K -π+)=0.27±0.04 (stat)±0.01 (syst), with significance exceeding 5 standard deviations. This is the first observation of CP violation in the decays of Bs0 mesons. Furthermore, we provide an improved determination of direct CP violation in B0→K+π- decays, ACP(B0→K+π-)=-0.080±0. 007 (stat)±0.003 (syst), which is the most precise measurement of this quantity to date. © 2013 CERN. Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.