Measurement of the CKM Angle Γ Using B ± → DK ± with D → K S 0 Π + Π − , K S 0 K + K − Decays

A binned Dalitz plot analysis of B ± → DK ± decays, with D→K_^S^0π^+π^- and D→K_^S^0K^+K^- , is performed to measure the CP -violating observables x ± and y ± , which are sensitive to the Cabibbo-Kobayashi-Maskawa angle γ . The analysis exploits a sample of proton-proton collision data corresponding to 3.0 fb −1 collected by the LHCb experiment. Measurements from CLEO-c of the variation of the strong-interaction phase of the D decay over the Dalitz plot are used as inputs. The values of the parameters are found to be x + = (−7.7 ± 2.4 ± 1.0 ± 0.4) × 10 − 2 , x − = (2.5 ± 2.5 ± 1.0 ± 0.5) × 10 − 2 , y + = (−2.2 ± 2.5 ± 0.4 ± 1.0) × 10 − 2 and y − = (7.5 ± 2.9 ± 0.5 ± 1.4) × 10 − 2 . The first, second, and third uncertainties are the statistical, the experimental systematic, and that associated with the precision of the strong-phase parameters. These are the most precise measurements of these observables and correspond to γ = (62 − 14 + 15 ) ° , with a second solution at γ → γ + 180 ° , and r B = 0.080 − 0.021 + 0.019 , where r B is the ratio between the suppressed and favoured B decay amplitudes.