Measurement of the CKM angle γ in B ^± → DK ^± and B ^± → Dπ ^± decays with D → KS0 h ⁺ h ⁻

A measurement of CP-violating observables is performed using the decays B^± → DK^± and B^± → Dπ^±, where the D meson is reconstructed in one of the self-conjugate three-body final states KS0π⁺π⁻ and KS0K⁺K⁻ (commonly denoted KS0h⁺h⁻). The decays are analysed in bins of the D-decay phase space, leading to a measurement that is independent of the modelling of the D-decay amplitude. The observables are inter- preted in terms of the CKM angle γ. Using a data sample corresponding to an integrated luminosity of 9 fb⁻¹ collected in proton-proton collisions at centre-of mass energies of 7, 8, and 13 TeV with the LHCb experiment, γ is measured to be (68.7−5.1+5.2)°. The hadronic parameters rBDK,rBDπ,δBDK,andδBDπ, which are the ratios and strong-phase differences of the suppressed and favoured B^± decays, are also reported. [Figure not available: see fulltext.]