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

A binned Dalitz plot analysis of the decays B 0 → DK ∗0 , with D → K S 0 π + π − and D → K S 0 K + 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)°, r B 0 = 0.56 ± 0.17 $$ {r_B}_{{}^0}=0.56\pm 0.17 $$ and δ B 0 = 20 4 − 20 + 21 ° $$ {\delta_B}_{{}^0}=\left(20{4}_{-20}^{+21}\right){}^{\circ} $$ . The parameters r B 0 $$ {r_B}_{{}^0} $$ and δ B 0 $$ {\delta_B}_{{}^0} $$ 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.