= Kaon CP mixing parameter
{title2=$\epsilon=\frac{\sqrt{R_{12}}-\sqrt{R_{21}}}{\sqrt{R_{12}}+\sqrt{R_{21}}}$}
In the flavor convention $K_1=(K^0-\bar K^0)/\sqrt2$ and $K_2=(K^0+\bar K^0)/\sqrt2$, the parameter $\epsilon=(a-b)/(a+b)$ writes normalized <mass> states as $(K_1+\epsilon K_2)/\sqrt{1+|\epsilon|^2}$ and $(K_2+\epsilon K_1)/\sqrt{1+|\epsilon|^2}$. In the Hermitian <mass>-only approximation with correlated roots, $\epsilon=i\tan(\varphi/2)$ and the states are <orthogonal>. For the full non-Hermitian decay matrix the real part need not vanish. The parameter depends on the flavor-state phase convention; observable <CP violation> involves convention-invariant combinations with decay amplitudes.
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