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

A binned Dalitz plot analysis of the decays B⁰ → 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 B⁰ decay amplitudes, and have been measured in a region of ±50 MeV/c² around the K^∗(892)⁰ mass and with the magnitude of the cosine of the K^∗(892)⁰ helicity angle larger than 0.4.