T , P -odd electron-nucleon interaction via a Higgs-boson exchange at the quark-gluon level

Abstract

The electron pseudoscalar-nucleon scalar T, P-odd interaction within the framework of the Standard Model is considered as an exchange mediated by the Higgs boson at the quark-gluon level. CP violation is introduced through a phase factor in the Cabibbo-Kobayashi-Maskawa matrix, which characterizes the flavor structure of the quark loop. We explicitly demonstrate that the total three-loop contribution vanishes for the Higgs-boson exchange mechanism. A nonzero contribution appears at the four-loop quark-gluon level only with the insertion of an additional gluon line between the quarks. The estimate of the CP-odd electron-nucleon interaction coupling constant after reduction of divergencies of the quark loop integral using the Glashow-Iliopoulos-Maiani (GIM) mechanism yields a value ∼10−28. The final result, expressed in terms of the equivalent electron electric dipole moment (eEDM), is 10−48 ecm, and its order of magnitude coincides with that of the GIM estimate of the eEDM at the quark-gluon level. Our parametric estimate of the eEDM differs from previous studies by a factor that depends on the mass of the b quark. Published by the American Physical Society 2025