CP Violation and Flavor SU(3) Breaking in D-meson Decays

We carry out a systematic flavor SU(3) analysis of D-meson decays including the leading order symmetry breaking effects. We find that SU(3) breaking can easily account for the recent LHCb measurement of the difference in CP asymmetries in the decays of $D^0$ into $K^+K^-$ and $\pi^+\pi^-$ mesons, once an enhancement mechanism, similar to the $\Delta=1/2$ rule in neutral kaon decays is assumed. As a byproduct of the analysis, one can make predictions regarding the individual asymmetries in $K^+K^-$, $\pi^+\pi^-$, as well as the $D^0 \to \pi^0\pi^0$ decay channels. Moreover, we find that the asymmetry in the decay $D^+\to \pi^+\pi^0$ vanishes in the leading approximation.