Model-independent measurement of the CKM angle γ using B⁰ → DK^∗0 decays with D → K <inf>S</inf>⁰ π ⁺ π ⁻ and K <inf>S</inf>⁰ K⁺K⁻

A binned Dalitz plot analysis of the decays B ⁰ → DK ^∗0, with D → K _S ⁰π ⁺π ⁻ and D → K _S ⁰K ⁺K ⁻, is performed to measure the observables x _± and y _±, which are related to the CKM angle γ and the hadronic parameters of the decays. The D decay strong phase variation over the Dalitz plot is taken from measurements performed at the CLEO-c experiment, making the analysis independent of the D decay model. With a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb ⁻¹, collected by the LHCb experiment, the values of the CP violation parameters are found to be x ₊ = 0.05 ± 0.35 ± 0.02, x ₋ = −0.31 ± 0.20 ± 0.04, y ₊ = −0.81 ± 0.28 ± 0.06 and y ₋ = 0.31 ± 0.21 ± 0.05, where the first uncertainties are statistical and the second systematic. These observables correspond to values γ = (71 ± 20)°, rB0=0.56±0.17 and δB0=(204−20+21)°. The parameters rB0 and δB0 are the magnitude ratio and strong phase difference between the suppressed and favoured B ⁰ decay amplitudes, and have been measured in a region of ±50 MeV/c ² around the K ^∗(892) ⁰ mass and with the magnitude of the cosine of the K ^∗(892) ⁰ helicity angle larger than 0.4.