Effective Field Theory with Two Higgs Doublets

TL;DR

This paper extends the effective field theory framework to a Two-Higgs-Doublet model, deriving operators up to dimension six and analyzing their effects on Higgs properties and pair production.

Contribution

It provides a complete set of dimension-six operators for the Two-Higgs-Doublet model and explores their impact on Higgs phenomenology and pair production processes.

Findings

Pair production of SM-like Higgses can be sizable due to dimension-six operators.

Effects on Higgs and gauge boson masses and couplings are explicitly computed.

Distinct from single Higgs models, fermion-Higgs couplings do not fix Higgs pair production.

Abstract

In this article we extend the effective field theory framework describing new physics effects to the case where the underlying low-energy theory is a Two-Higgs-Doublet model. We derive a complete set of independent operators up to dimension six assuming a $Z_2$-invariant CP-conserving Higgs potential. The effects on Higgs and gauge boson masses, mixing angles in the Higgs sector as well as couplings to fermions and gauge bosons are computed. At variance with the case of a single Higgs doublet, we find that pair production of SM-like Higgses, arising through dimension-six operators, is not fixed by fermion-fermion-Higgs couplings and can therefore be sizable.