  The LHCb and CDF Collaborations have recently reported evidence for a CP
asymmetry around -0.7% in $\Delta A_{CP}$, the difference between $A_{CP}(D^0
\to K^+ K^-)$ and $A_{CP}(D^0 \to \pi^+\pi^-)$. In the Standard Model this
effect may be accounted for by enhanced $1/m_c$ corrections in a CP-violating
penguin amplitude governed by a Cabibbo-Kobayashi-Maskawa (CKM) factor
$V^*_{cb}V_{ub}$. A consistent scheme based on broken flavor SU(3) is presented
relating Cabibbo-favored (CF) and singly-Cabibbo-suppressed (SCS) $D$ meson
decay rates into two pseudoscalars. Two important ingredients supporting the
above interpretation for $\Delta A_{CP}$ are a large exchange amplitude in CF
decays which is formally $1/m_c$-suppressed, and a pure $\Delta U=0$ U-spin
breaking CP-conserving penguin amplitude involving $V^*_{cs}V_{us}$ and
$V^*_{cd}V_{ud}$ which accounts for the difference between the $D^0\to K^+K^-$
and $D^0\to \pi^+\pi^-$ decay rates. The magnitudes of the CP conserving and CP
violating penguin amplitudes, where the former involves U-spin breaking at a
level of 10%, are shown to be related to each other by the magnitudes of
corresponding CKM factors. This simple scheme leads to preferable sign
predictions for CP asymmetries in charmed meson decays into two pseudoscalars
and to correlations between asymmetries in two pairs of these processes.
