Measurement of the CKM angle γ using B ⁰ → DK ^*0 with D → K S⁰ π ⁺ π ⁻ decays

A model-dependent amplitude analysis of the decay B ⁰ → D(K _S ⁰π ⁺π ⁻)K ^∗0 is performed using proton-proton collision data corresponding to an integrated luminosity of 3.0 fb ⁻¹, recorded at √s=7 and 8 TeV by the LHCb experiment. The CP violation observables x _± and y _±, sensitive to the CKM angle γ, are measured to bex−=−0.15±0.14±0.03±0.01,y−=0.25±0.15±0.06±0.01,x+=0.05±0.24±0.04±0.01,y+=−0.65 _−0.23 ^+0.24±0.08±0.01, where the first uncertainties are statistical, the second systematic and the third arise from the uncertainty on the D → K _S ⁰π ⁺π ⁻ amplitude model. These are the most precise measurements of these observables. They correspond to γ = (80 ₋₂₂ ⁺²¹)° and r _{B ⁰} =0.39±0.13, where r _{B ⁰} is the magnitude of the ratio of the suppressed and favoured B ⁰ → DK ⁺π ⁻ decay amplitudes, in a Kπ mass region of ±50 MeV around the K ^*(892) ⁰ mass and for an absolute value of the cosine of the K ^*0 decay angle larger than 0.4.[Figure not available: see fulltext.]