  Dark photon physics has attracted significant theoretical and experimental
attention. A dark photon from a $U(1)_X$ gauge group can have renormalizable
kinetic mixing with the $U(1)_Y$ gauge boson of the SM $SU(3)_C\times
SU(2)_L\times U(1)_Y$ gauge group. It only permits CP conserving mixing. When a
$SU(2)_L$ triplet scalar with a non-zero vacuum expectation value is
introduced, a dimension 5 operator can be constructed to generate a CP
violating kinetic mixing. To further realize a renormalizable model for CP
violating kinetic mixing, new ingredients are needed. We construct for the
first time such a model. We find that the triplet leptons in type-III seesaw
model can play the crucial role in building such a renormalizable model. This
natural connection of dark photon and neutrino physics may have important
implications about how new physics might emerge. The CP violating kinetic
mixing induced electron electric dipole moment (EDM) can be as large as current
experimental bounds. The model can be further tested by improved measurement of
electron EDM.
