Measurement of $CP$ violation of neutral kaon system in $J/\ddot{I}ˆ$ decay at the Super Tau-Charm Facility

Abstract

In this paper, we present a preliminary study of $CP$ violation effect of $K^0-{\bar{K}}^0$ system in $J/\ddot{I}ˆ$ decay. The $CP$ violation parameters $\hat{I}{\cdot }_{+-}$ and $\hat{I}{\cdot }_{00}$ as well as their corresponding phase $\ddot{I}{•}_{+-}$ and $\ddot{I}{•}_{00}$ can be determined by the difference of the time-dependent decay rates between $K^0$ and ${\bar{K}}^0$ produced from $J/\ddot{I}ˆ\to K^{-}\ddot{I}{€}^{+}{K}^0+c.c.$ processes. We investigate the precisions of the measurements of the CP violation effect at the Super Tau-Charm facility(STCF), a $e^{+}{e}^{-}$ collider with a peak luminosity of $0.5\times 10^{35}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$. The parameters $\hat{I}{\cdot }_{+-}$ and its phase $\ddot{I}{•}_{+-}$ can be measured at a relative precision of $1\times 10^{-3}$, which the statistical accuracy will be several times better than that of the existing PDG average values.