A Measurement of Lifetime Difference in $D^0$ Meson Decays

TL;DR

This paper reports a measurement of the $D^0$-$ar{D}^0$ mixing parameter $y_{CP}$ using data from the Belle detector, finding results consistent with no mixing within uncertainties.

Contribution

First measurement of $y_{CP}$ using lifetime differences in $D^0$ decays at Belle, providing new constraints on charm mixing parameters.

Findings

Measured $y_{CP} = (-0.5 \, ext{±} \, 1.0^{+0.7}_{-0.8})\times10^{-2}$

95% confidence interval for $y_{CP}$ is $-0.030$ to $0.020$

Results are consistent with no $D^0$-$\bar{D}^0$ mixing within errors.

Abstract

We report a measurement of the $D^0$-$\bar{D}{}^0$ mixing parameter $y_{CP}$ using 23.4 fb$^{-1}$ of data collected near the $\Upsilon$(4S) resonance with the Belle detector at KEKB. $y_{CP}$ is measured from the lifetime difference of $D^0$ mesons decaying into the $K^-\pi^+$ state and the CP even eigenstate $K^-K^+$. We find $y_{CP}=(-0.5\pm 1.0{}^{+0.7}_{-0.8})\times10^{-2}$, where the first error is statistical and the second systematic, corresponding to a 95% confidence interval $-0.030 < y_{CP} < 0.020$.