  If New Physics contributes significantly to neutral meson mixing, then it is
quite likely that it does so in a CP violating manner. In $D^0-\bar D^0$ mixing
measured through $D^0\rightarrow K^+\pi^-$, CP violation induces a term
$\propto te^{-\Gamma t}$ with important implications for experiments. For
$B_s-\bar B_s$ mixing, a non-vanishing CP asymmetry (above a few percent)
$a_{CP}(B_s \rightarrow D_s^+ D_s^-)$ is a clear signal of New Physics.
Interestingly, this would test precisely the same Standard Model ingredients as
the question of whether $\alpha+\beta+\gamma=\pi$.
