Low-energy effective Lagrangian of the two-Higgs-doublet model

Abstract

We consider a decoupling scenario within the two-Higgs-doublet model (2HDM) with small CP-violation. Mass eigenstates of this model include one neutral scalar field with the mass of the Standard model (SM) Higgs boson and four other scalars, which decouple at low energies. We derive the effective operators of interactions between the SM fermions and the lightest scalar particle of the model. The coefficients at these operators are expressed in terms of the 2HDM parameters. The scattering processes affected by this effective Lagrangian are identified.