Measurement of D^{0}-D[Over ¯]^{0} Mixing Using the Ratio of Lifetimes for the Decays D^{0}→K^{-}Π^{+}, K^{-}K^{+}, and Π^{-}Π^{+}

We present a measurement of D-0-(D) over bar (0) mixing parameters using the ratios of lifetimes extracted from a sample of D-0 mesons produced through the process D*+ -> D-0 pi(+), which decay to K-pi(+), K-K+, or pi(-)pi(+). The lifetimes of the CP-even, Cabibbo-suppressed modes K-K+ and pi(-)pi(+) are compared with that of the CP-mixed, Cabibbo-favored mode K-pi(+) to obtain a measurement of y(CP), which in the limit of CP conservation corresponds to the mixing parameter y. The analysis is based on a data sample of 384 fb(-1) collected by the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider. We obtain y(CP) = [1.24 +/- 0.39(stat) +/- 0.13(syst)]%, which is evidence for D-0-(D) over bar (0) mixing at the 3 sigma level, and Delta Y = [-0.26 +/- 0.36(stat) +/- 0.08(syst)]%, where Delta Y constrains possible CP violation. Combining this result with a previous BABAR measurement of y(CP) obtained from a separate sample of D-0 -> K-K+ events, we obtain y(CP) = [1.03 +/- 0.33(stat) +/- 0.19(syst)]%.