Charm CP violation and mixing at Belle

TL;DR

This paper reports the first observation of charm meson mixing in electron-positron collisions at Belle, providing the most precise measurements of mixing and CP violation parameters, consistent with Standard Model predictions.

Contribution

It presents the first observation of $D^0-ar{D}^0$ mixing in $e^+e^-$ collisions and offers the most precise measurements of mixing and CP violation parameters to date.

Findings

First observation of $D^0-ar{D}^0$ mixing in $e^+e^-$ collisions.

Most precise measurements of mixing and CP violation parameters.

Results are consistent with Standard Model predictions.

Abstract

We present charm CP violation and mixing measurements at Belle. They are the first observation of $D^0-\bar{D}^0$ mixing in $e^+e^-$ collisions from $D^0\rightarrow K^+\pi^-$ decays, the most precise mixing and indirect CP violation parameters from $D^0\rightarrow K^0_S\pi^+\pi^-$ decays, and the time-integrated CP asymmetries in $D^0\rightarrow\pi^0\pi^0$ and $D^0\rightarrow K^0_S\pi^0$ decays. Our mixing measurement in $D^0\rightarrow K^+\pi^-$ decays excludes the no-mixing hypothesis at the 5.1 standard deviation level. The mixing parameters $x=(0.56\pm0.19^{+0.03+0.06}_{-0.09-0.09})%$, $y=(0.30\pm0.15^{+0.04+0.03}_{-0.05-0.06})%$ and indirect CP violation parameters $|q/p|=(0.90^{+0.16+0.05+0.06}_{-0.15-0.04-0.05})$, arg$(q/p)=(-6\pm11\pm3^{+3}_{-4})^{\circ}$ measured from $D^0\rightarrow K^0_S\pi^+\pi^-$ decays, and the time-integrated CP asymmetries $A^{D^0\rightarrow\pi^0\pi^0}_{CP}=(-0.03\pm0.64\pm0.10)%$ and $A^{D^0\rightarrow K^0_S\pi^0}_{CP}=(-0.21\pm0.16\pm0.07)%$ are the most precise measurements to date. Our measurements here are consistent with predictions of the standard model.