Measurement of the charm-mixing parameter $y_{CP}$ in $D^0\to K_S^0\omega$ decays at Belle

Abstract

We report the first measurement of the charm-mixing parameter $y_{CP}$ in $D^0$ decays to the $CP$-odd final state $K_S^0\omega$. The study uses the full Belle $e^{+}{e}^{-}$ annihilation data sample of $976\mathrm{f}{\mathrm{b}}^{-1}$ taken at or near the ${\rm Y}(4S)$ centre-of-mass energy. We find $y_{CP}=(0.96\pm 0.91\pm 0.61{}_{-0.00}^{+0.17})\%$, where the first uncertainty is statistical, the second is systematic due to event selection and background, and the last is due to possible presence of $CP$-even decays in the data sample.

8 pages, 2 figures