Direct CP Violation in D -> hh Decays

Evidence of CP violation in the charm sector has been observed recently by the LHCb and CDF Collaborations. The issue of whether it can be accommodated within the standard model (SM) is examined in this talk. We conclude that the CP asymmetry difference $\Delta a_{CP}^{\rm dir}$ between $D^0 \to K^+ K^-$ and $D^0 \to \pi^+ \pi^-$ is of order $-(0.14\sim 0.15)$. If the improved theoretical estimate of $\Delta a_{CP}^{\rm dir}$ in the SM remains to be a few per mille and the experimental measurement continues to be large with more statistics in the future, it will be clear evidence of physics beyond the SM in the charm sector.