Impact of a CP Violating Higgs: from LHC to Baryogenesis

TL;DR

This paper explores how CP violation in the Higgs sector, constrained by LHC data and electric dipole moments, can provide the necessary conditions for electroweak baryogenesis, highlighting the potential for direct CP violation measurements at the LHC.

Contribution

It establishes a connection between LHC Higgs data, electric dipole moments, and baryogenesis within the 2HDM framework, offering a comprehensive parametrization and global fit analysis.

Findings

Current LHC data favor a nonzero CP-violating phase for certain parameters.

EDM constraints still permit significant CP-violating phases.

Room exists for Higgs sector CP violation to explain baryon asymmetry.

Abstract

We observe a generic connection between LHC Higgs data and electroweak baryogenesis: the particle that contributes to the CP odd $hgg$ or $h \gamma \gamma$ vertex would provide the CP violating source during a first order phase transition. It is illustrated in the 2HDM that a common complex phase controls the lightest Higgs properties at the LHC, electric dipole moments and the CP violating source for electroweak baryogenesis. We perform a general parametrization of Higgs effective couplings and a global fit to the LHC Higgs data. Current LHC measurements prefer a nonzero phase for $\tan \beta \lesssim 1$ and EDM constraints still allow an order one phase for $\tan\beta\sim1$, which gives sufficient room to generate the correct cosmic baryon asymmetry. We also give some prospects in the direct measurements of CP violation in the Higgs sector at the LHC.