Constraining the CP structure of Higgs-fermion couplings with a global LHC fit, the electron EDM and baryogenesis

TL;DR

This paper uses LHC Higgs measurements and electron EDM bounds to constrain the CP-violating structure of Higgs-fermion couplings, exploring their potential role in baryogenesis and identifying the limitations of current data.

Contribution

It provides a comprehensive global fit of Higgs-fermion CP violation, combining collider data with EDM constraints, and assesses their implications for baryogenesis.

Findings

Complex tau Yukawa coupling could explain baryon asymmetry with uncertainties.

Combined top and bottom Yukawa CP violation enhances baryogenesis contribution.

Current data insufficient to fully account for observed baryon asymmetry.

Abstract

CP violation in the Higgs couplings to fermions is an intriguing, but not yet extensively explored possibility. We use inclusive and differential LHC Higgs boson measurements to fit the CP structure of the Higgs Yukawa couplings. Starting with simple effective models featuring CP violation in a single Higgs-fermion coupling, we probe well-motivated models with up to nine free parameters. We also investigate the complementarity of LHC constraints with the electron electric dipole moment bound, taking into account the possibility of a modified electron Yukawa coupling, and assess to which extent CP violation in the Higgs-fermion couplings can contribute to the observed baryon asymmetry of the universe. Even after including the recent analysis of angular correlations in $H\to\tau^+\tau^-$ decays, we find that a complex tau Yukawa coupling alone may be able to account for the observed baryon asymmetry, but with large uncertainties in the baryogenesis calculation. A combination of complex top and bottom quark Yukawa couplings yields a result four times larger than the sum of their separate contributions, but remains insufficient to account for the observed baryon asymmetry.