Speaker
Description
In this talk, we investigate the conditions required to support large CP violation in the Complex Two-Higgs-Doublet Model (C2HDM). By performing a comprehensive global scan of Type-I and Type-II models—incorporating theoretical stability, collider constraints, and the stringent electron EDM (eEDM) bound—we identify distinct phenomenological pathways to large CP-violating effects. We show that the Type-I model faces a "no-lose" scenario: all viable points predict a strict lower bound on the eEDM within the reach of next-generation experiments, with sizable gauge-sector CP violation emerging only when the 125 GeV Higgs is nearly degenerate with a second neutral state. In contrast, Type-II suppresses gauge-sector CP violation but allows for maximal CP mixing in the heavy-Higgs Yukawa sector. Finally, we uncover a phenomenon of "hidden CP violation" in the Higgs alignment limit, where maximal CP mixing persists in the heavy sector despite decoupling from the weak gauge bosons; we demonstrate that this elusive scenario can be directly probed through specific cubic interactions involving the charged Higgs boson.