The cancellation mechanism in the predictions of electric dipole moments

TL;DR

This paper introduces a cancellation mechanism in theoretical predictions of electric dipole moments, allowing significant CP violation in Higgs sectors without conflicting with current experimental constraints, and explores its implications in various models.

Contribution

It proposes a general cancellation mechanism involving Higgs mass splitting that can reconcile large CP violation with EDM constraints, applicable to multiple new physics models.

Findings

Cancellation mechanism depends on Higgs mass degeneracy

Allows large CP violation consistent with current EDM limits

Future experiments can test this mechanism

Abstract

The interpretation of the baryon asymmetry of the Universe necessitates the CP violation beyond the Standard Model (SM). We present a general cancellation mechanism in the theoretical predictions of the electron electric dipole moments (EDM), quark chromo-EDMs, and Weinberg operators. A relative large CP violation in the Higgs sector is allowed by the current electron EDM constraint released by the ACME collaboration in 2013, and the recent $^{199}$Hg EDM experiment. The cancellation mechanism can be induced by the mass splitting of heavy Higgs bosons around $\sim\mathcal{O}(0.1-1)$ GeV, and the extent of the mass degeneracy determines the magnitude of the CP-violating phase. We explicate this point by investigating the CP-violating two-Higgs-doublet model and the minimal supersymmetric Standard Model. The cancellation mechanism is general when there are CP violation and mixing in the Higgs sector of new physics models. The CP-violating phases in this scenario can be excluded or detected by the projected $^{225}$Ra EDM experiments with precision reaching $\sim10^{-28}\,e\cdot{\rm cm}$, as well as the future colliders.