so providing a remarkable hint for our understanding of CP violation.

On the relevant combination of Yukawa couplings
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Once a theory is specified, it is relatively easy to list the combinations of Yukawa couplings appearing in the slepton mass radiative corrections that may contribute to lepton EDMs. However, the actual calculation is more involved as we now turn to discuss.

As an example, let us look for ${\cal I}m(A_{ii})$ by studying the evolution of $A_e$ in the case of degenerate right-handed neutrino masses, $\bar M$, for simplicity. Let us first consider the case of the pure seesaw and define [^6] the hermitian matrices $E \equiv y_e^{\dagger} y_e$, $N \equiv y_{\nu} ^{\dagger} y_{\nu}$. Notice that $E$ is real and diagonal in the LF defining basis and $N$ is diagonalized by a unitary matrix similar to the CKM one with only one phase (even for non-degenerate right-handed neutrinos). By solving the RGE for $A_e$, eq. (\[Ae\_ss\]), linearly in $t_3 \equiv 1/(4 \pi)^2$ $\ln(M_{Pl}/\bar M)$, $A_e$ can only be proportional to $y_e E$ and $y_e N$, whose diagonal elements are real. At $O(t_3^2)$ only $y_e EE, y_e NN, y_e NE$ and $y_e EN$ appear, whose diagonal elements are again real. A potential 