Measurement of D0-anti-D0 Mixing using the Ratio of Lifetimes for the Decays D0 --> K-pi+, K-K+, and pi-pi+

Abstract

We present a measurement of $D^0$-$\overline{D^0}$ mixing parameters using the ratios of lifetimes extracted from a sample of $D^0$ mesons produced through the process $D^{*+}\to\D^0π^+$, that decay to $K^{+}{\pi }^{-}$, K^{-}K^{+}$,or$π^-π^+$.TheCabibbo-suppressedmodes$K^{-}K^{+}$and$π^-π^+$arecomparedtotheCabibbo-favoredmode$K^{+}π^{-}$toobtainameasurementof$y_{CP}$,whichinthelimitofCPconservationcorrespondstothemixingparameter$y$.Theanalysisisbasedonadatasampleof384$fb^{-1}$collectedbythe$BaBar$detectoratthePEP-IIasymmetric-energy$e^+e^-$collider.Weobtain$y_{CP} = [1.24\pm 0.39\mathrm{(stat)} \pm 0.13\mathrm{(syst)}]%$,whichisevidenceof$D^0$-$\bar{D^0}$mixingatthe$3σ$level,and$ΔY = [-0.26\pm 0.36\mathrm{(stat)} \pm 0.08 \mathrm{(syst)}]%$,where$ΔY$constrainspossibleCPviolation.Combiningthisresultwithaprevious$BaBar$measurementof$y_{CP}$obtainedfromaseparatesampleof$D^0\to K^{-}K^{+}$events,weobtain$y_{CP} = [1.03\pm 0.33 \mathrm{(stat)} \pm 0.19 \mathrm{(syst)}]%$.

8 pages, 9 postscript figures, submitted to PRD-RC