Measurement of the charm-mixing parameter yCP in D0→KS0ω decays at Belle

We report the first measurement of the charm-mixing parameter y$_{CP}$ in D$^{0}$ decays to the CP-odd final state K0¦Sω. The study uses the full Belle e$^{+}$e$^{-}$ annihilation data sample of 976 fb$^{-1}$ taken at or near the Υ(4S) centre-of-mass energy. We find y$_{CP}$=(0.96±0.91±0.62(+0.17)¦(-0.00))%, 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.