Measurement of the Charge Asymmetry in the DecayKL0→π±+e∓+ν

The charge asymmetry $\delta =\frac{({\Gamma }_{+}-{\Gamma }_{-})}{({\Gamma }_{+}+{\Gamma }_{-})}$ for the electron in the decay of the long-lived neutral kaon to pion, electron, and neutrino has been measured. We find asymmetry $\delta =(+2.24\mathrm{}\pm 0.36)\times {10}^{-3\mathrm{}}$. The result shows that $\mathrm{CP}$ symmetry is not conserved in this process.