A model-independent Dalitz plot analysis of B±→DK± with D→K0Sh+h− (h=π,K) decays and constraints on the CKM angle γ

Abstract

A binned Dalitz plot analysis of B± → DK± decays, with D → K0 Sπ+π− and D → K0 S 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 modelbased 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) × 10−2, y− = (2.7 ± 5.2 ± 0.8 ± 2.3) × 10−2, x+ = (−10.3 ± 4.5 ± 1.8 ± 1.4) × 10−2 and y+ = (−0.9 ± 3.7 ± 0.8 ± 3.0) × 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+43 −38) ◦, with a second solution at γ → γ + 180◦, and rB = 0.07 ± 0.04, where rB is the ratio between the suppressed and favoured B decay amplitudes.