Measurement of D^{0}-D[over ¯]^{0} Mixing Parameters Using D^{0}→K_{S}^{0}π^{+}π^{-} and D^{0}→K_{S}^{0}K^{+}K^{-} Decays

We report a direct measurement of D0-D̅ 0 mixing parameters through a time-dependent amplitude analysis of the Dalitz plots of D0→KS0π+π- and, for the first time, D0→KS0K+K- decays. The low-momentum pion πs+ in the decay D*+→D0πs+ identifies the flavor of the neutral D meson at its production. Using 468.5  fb-1 of e+e- colliding-beam data recorded near √s=10.6  GeV by the BABAR detector at the PEP-II asymmetric-energy collider at SLAC, we measure the mixing parameters x=[1.6±2.3(stat)±1.2(syst)±0.8(model)]×10-3, and y=[5.7±2.0(stat)±1.3(syst)±0.7(model)]×10-3. These results provide the best measurement to date of x and y. The knowledge of the value of x, in particular, is crucial for understanding the origin of mixing.