$D^0$-${\bar{D}}^0$ mixing and CP violation results from Belle

Abstract

We report the results on $D^0$-${\bar{D}}^0$ mixing in the decays of $D^0\to K^{+}{\pi }^{-}$ and $D^0\to K_S^0{\pi }^{+}{\pi }^{-}$, and CP violation in $D^0\to {\pi }^0{\pi }^0$ using a data sample with an integrated luminosity of about 1~ab${}^{-1}$ recorded with the Belle detector, at different center of mass energies. The mixing is observed in $D^0\to K^{+}{\pi }^{-}$ with the mixing parameters $x^{\prime 2}=(0.09\pm 0.22)\times 10^{-3}$, $y^{\prime }=(4.6\pm 3.4)\times 10^{-3}$ and the ratio of doubly Cabibbo-suppressed to Cabibbo-favored decay rates $R_D=(3.53\pm 0.13)\times 10^{-3}$, where the quoted uncertainties combine both statistical and systematic contributions. For the $D^0\to K_S^0{\pi }^{+}{\pi }^{-}$ decay, assuming CP conservation we measure mixing parameters $x=(0.56\pm 0.19_{-0.09-0.09}^{+0.03+0.06})\%$ and $y=(0.30\pm 0.15_{-0.05-0.06}^{+0.04+0.03})\%$, where the uncertainties are statistical, experimental systematics, and that due to amplitude model. We measure the mixing parameters allowing CP violation for this decay mode, and obtain $|q/p|=0.90_{-0.15-0.04-0.05}^{+0.16+0.05+0.06}$ and arg($q/p$)=$(-6\pm 11\pm 3_{-4}^{+3}{)}^{\circ }$ that are consistent with no CP violation. The time-integrated CP asymmetry in the decay $D^0\to {\pi }^0{\pi }^0$ is measured to be, $[-0.03\pm 0.64(stat)\pm 0.10(syst)]\%$, consistent with CP conservation. We also present an updated measurement of CP asymmetry in $D^0\to K_S^0{\pi }^0$.

References in corpus (1)

• Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of summer 2016