= Solution
Direct <CP violation> means unequal magnitudes of CP-conjugate decay <probability amplitudes>:
$$
\boxed{|A_f|\ne|\bar A_{\bar f}|.}
$$
It changes <Decay rate>[decay probabilities] even at $t=0$, before any mixing. For a common <CP eigenstate> final state, this reduces to $|A_f|\ne|\bar A_f|$. Usually it requires interfering decay contributions with different <Weak phase>[weak phases] and different <Absorptive phase of a decay amplitude>[strong phases]; it is not equivalent to a nonzero weak <phase> in one isolated <probability amplitude>.
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