Past exam of the particle physics course of the University of Oxford / 2018 / 3 / c / ii

CP violation in mixing occurs whenThe flavour-transition probabilities are proportional to $|q/p{|}^2|g_{-}{|}^2$ for $K^0\to {\bar{K}}^0$, and $|p/q{|}^2|g_{-}{|}^2$ for the reverse. Their inequality remains when decay probability amplitudes themselves conserve CP. The coefficients multiplying the mixed-decay terms in the rate equations encode this asymmetry.