Semi-Phenomenological Approach to the Estimate of CP Effects in $K^{\pm }\to 3\pi$ Decays

The amplitudes of the $K^{\pm }\to 3\pi$ and $K\to 2\pi$ decays are expressed in terms of different combinations of one and the same set of CP-conserving and CP-odd parameters. Extracting the magnitudes of these parameters from the data on $K\to 2\pi$ dacays, we estimate an expected CP-odd difference between the values of the slope parameters $g^{+}$ and $g^{-}$ of the energy distributions of “odd” pions in $K^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}$ and $K^- \to \pi^-\pi^-\pi^+$ decays.