Measurement of mixing and CP violation parameters in two-body charm decays

A study of mixing and indirect CP violation in D 0 mesons through the determination of the parameters y CP and A Γ is presented. The parameter y CP is the deviation from unity of the ratio of effective lifetimes measured in D 0 decays to the CP eigenstate K +K - with respect to decays to the Cabibbo favoured mode K -π +. The result measured using data collected by LHCb in 2010, corresponding to an integrated luminosity of 29 pb -1, is yCP = (5.5 ± 6.3 stat ± 4.1 syst) × 10 -3. The parameter A Γ is the asymmetry of effective lifetimes measured in decays of D 0 and D̄ 0 mesons to K +K -. The result is A Γ = (-5.9 ± 5.9 stat ± 2.1 syst) × 10 -3. A data-driven technique is used to correct for lifetime-biasing effects. Copyright CERN.