In summary, this Letter reports the first observation of a nonzero CP asymmetry in charm decays, using large samples of D⁰ → K⁻K⁺ and D⁰ → π⁻π⁺ decays collected with the LHCb detector. The result is consistent with, although at the upper end of, SM expectations, which lie in the range 10⁻⁴–10⁻³ [8–13]. Beyond the SM, the rate of CP violation could be enhanced. Unfortunately, present theoretical understanding does not allow very precise predictions to be made, due to the presence of strong-interaction
effects which are difficult to compute. In the next decade, further measurements with charmed particles, along with possible theoretical improvements, will help clarify the physics picture, and establish whether this result is consistent with the SM or indicates the presence of new dynamics in the up-quark sector.
from the paper (links in my other comment). SM = standard model.