Measurement of $CP$ violation of neutral kaon system in $J/\psi$ decay at the Super Tau-Charm Facility

TL;DR

This study explores $CP$ violation in the neutral kaon system via $J/ar{J}$ decays at the Super Tau-Charm Facility, aiming for high-precision measurements surpassing current averages.

Contribution

It proposes a method to measure $CP$ violation parameters in $K^{0}-ar{K}^{0}$ using $J/ar{J}$ decays at STCF, with improved precision over existing data.

Findings

Potential to measure $ ext{Re}(rac{ar{ ho}}{ ho})$ with high accuracy.

Expected measurement precision for $ ext{Re}(rac{ar{ ho}}{ ho})$ is around 1%.

Statistical accuracy surpasses current PDG averages.

Abstract

In this paper, we present a preliminary study of $CP$ violation effect of $K^{0}-\bar{K}^{0}$ system in $J/\psi$ decay. The $CP$ violation parameters $\eta_{+-}$ and $\eta_{00}$ as well as their corresponding phase $\phi_{+-}$ and $\phi_{00}$ can be determined by the difference of the time-dependent decay rates between $K^{0}$ and $\bar{K}^{0}$ produced from $J/\psi \rightarrow K^{-}\pi^{+}K^{0} + c.c.$ 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 $0.5\times10^{35}\ \rm{cm}^{-2}\rm{s}^{-1}$. The parameters $\eta_{+-}$ and its phase $\phi_{+-}$ 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.