Measurement of the CKM angle γ using B ± → DK ± with D → K S 0 π + π −, K S 0 K + K − decays

A binned Dalitz plot analysis of B DK decays, with D K 0 S + - and D K 0 S K + K -, is performed to measure the CP -violating observables x and y , which are sensitive to the Cabibbo-Kobayashi-Maskawa angle . The analysis exploits a sample of proton-proton collision data corresponding to 3.0 fb -1 collected by the LHCb experiment. Measurements from CLEO-c of the variation of the strong-interaction phase of the D decay over the Dalitz plot are used as inputs. The values of the parameters are found to be x + = (-7.7 2.4 1.0 0.4) 10 -2 , x -= (2.5 2.5 1.0 0.5) 10 -2 , y + = (-2.2 2.5 0.4 1.0) 10 -2 , and y -= (7.5 2.9 0.5 1.4) 10 -2 . The first, second, and third uncertainties are the statistical, the experimental systematic, and that associated with the precision of the strong-phase parameters. These are the most precise measurements of these observables and correspond to = (62 +15 -14 ) , with a second solution at + 180 , and r B = 0.080 +0.019 -0.021 , where r B is the ratio between the suppressed and favoured B decay amplitudes.