Evidence for $D^0-{\bar{D}}^0$ Mixing

Abstract

We observe evidence for $D^0-{\bar{D}}^0$ mixing by measuring the difference in apparent lifetime when a $D^0$ meson decays to the CP eigenstates $K^{+}{K}^{-}$ and $\ddot{I}{€}^{+}\ddot{I}{€}^{-}$, and when it decays to the final state $K^{-}\ddot{I}{€}^{+}$. We find $y_{CP}=(1.31\pm 0.32(stat.)\pm 0.25(syst.))$, 3.2 standard deviations from zero. We also search for a CP asymmetry between $D^0$ and ${\bar{D}}^0$ decays; no evidence for CP violation is found. These results are based on 540 fb${}^{-1}$ of data recorded by the Belle detector at the KEKB $e^{+}{e}^{-}$ collider.

6 pages, 2 figures, submitted to PRL