Electric Dipole Moments in the CP-violating Generational Three-Higgs-Doublet Model

Abstract

Motivated by the Yukawa interactions in the CP-violating Generational Three-Higgs-Doublet Model (G3HDM), we investigate the electric dipole moments (EDMs) of the $b$ quark, $c$ quark, electron, neutron, and mercury atom, imposing constraints from the observed $125~\mathrm{GeV}$ Higgs signals, flavor physics, and rare $B$-meson decays. We find that the $b$ quark, neutron, and mercury EDMs are predominantly controlled by top-enhanced charged-Higgs amplitudes, whose internal cancellations are generally weak. Meanwhile, pronounced pairwise cancellations between nearly degenerate neutral Higgs states occur in the $c$ quark, electron, neutron, and mercury EDMs. Using degenerate perturbation theory, we show that these cancellations originate from approximate relations among the neutral-Higgs mixing-matrix elements, which enforce the anti-alignment of the corresponding CP-odd coupling invariants.