A Model-Independent Dalitz Plot Analysis of B± → D K± with D → K0S h+ h− (h = π, K) Decays and Constraints on the CKM Angle γ

A binned Dalitz plot analysis of B± → D K± decays, with D → K0S π+ π− and D → K0S K+ K−, is performed to measure the CP-violating observables x_± and y_± which are sensitive to the CKM angle γ. The analysis exploits 1.0 fb^−1 of data collected by the LHCb experiment. The study makes no model-based assumption on the variation of the strong phase of the D decay amplitude over the Dalitz plot, but uses measurements of this quantity from CLEO-c as input. The values of the parameters are found to be x_− = (0.0 ± 4.3 ± 1.5 ± 0.6) x 10^−2, y_− = (2.7 ± 5.2 ± 0.8 ± 2.3) x 10^−2, x_+ = (−10.3 ± 4.5 ± 1.8 ± 1.4) x 10^−2 and y_+ = (−0.9 ± 3.7 ± 0.8 ± 3.0) x 10^−2. The first, second, and third uncertainties are the statistical, the experimental systematic, and the error associated with the precision of the strong-phase parameters measured at CLEO-c, respectively. These results correspond to γ = (44_{−38}^{+43})∘, with a second solution at γ → γ + 180∘, and r_B = 0.07 ± 0.04, where r_B is the ratio between the suppressed and favoured B decay amplitudes.