Speaker
Mr.
Nisar Nellikunnummel
(Tata Institute of Fundamental Research)
Description
We search for CP violation in $D^0$ and $\bar{D}^0$ decays to the $\pi^0 \pi^0$ final state and measure $D^0$-$\bar{D}^0$ mixing in the decays of $D^0 \to K^+ \pi^-$ and $K_S ^0 \pi^+ \pi^-$. The asymmetry obtained in the rate of $D^0$ and $\bar{D}^0$ decays to the $\pi^0 \pi^0$ final state, $[-0.03 \pm 0.64(stat) \pm 0.10(syst)]\%$, is consistent with no CP violation. The mixing parameters are measured to be ${x'}^2 = (0.09 \pm 0.22) \times 10^{-3}$ and $y' = (4.6 \pm3.4) \times 10^{-3}$ for $D^0 \to K^+ \pi^-$, and $x = (0.56 \pm 0.19^{+0.03}_{-0.09}{^{+0.06}_{-0.09}})\%$ and $y = (0.30 \pm 0.15^{+0.04}_{-0.05}{^{+0.03}_{-0.06})}\%$ for $D^0 \to K_S^0 \pi^+ \pi^-$. In $D^0 \to K^+ \pi^-$, the ratio of doubly Cabibbo-suppressed to Cabibbo-favored decay rates $R_D = (3.53 \pm 0.13) \times 10^{-3}$, which excludes the no-mixing hypothesis at the 5.1 standard deviation level. In $D^0 \to K_S^0 \pi^+ \pi^-$, with CP-violation allowed, the parameters $|q/p|=0.90^{+0.16}_{-0.15}{^{+0.05}_{-0.04}}{^{+0.06}_{-0.05}}$ and $\arg(q/p)=(-6 \pm 11{\pm3}{^{+3}_{-4}})^{\circ}$ are found to be consistent with conservation of CP-symmetry in mixing.
Primary author
Prof.
Youngjoon Kwon
(Yonsei University)
