Higgs Couplings in Composite Models

TL;DR

This paper analyzes Higgs couplings in the SO(5)/SO(4) composite Higgs model, showing certain couplings are unaffected by light fermionic resonances and are governed by Goldstone symmetry and partial compositeness.

Contribution

It demonstrates that Higgs couplings to gluons and photons are insensitive to elementary-composite mixings and equal to SM values at leading order, highlighting symmetry-based properties.

Findings

Higgs couplings to gluons and photons are unaffected by light fermionic resonances.

Higgs couplings to tops and gluons are equal at leading order when normalized to the SM.

These properties are derived from Goldstone symmetry and partial compositeness assumptions.

Abstract

We study Higgs couplings in the composite Higgs model based on the coset SO(5)/SO(4). We show that the couplings to gluons and photons are insensitive to the elementary-composite mixings and thus not affected by light fermionic resonances. Moreover, at leading order in the mixings the Higgs couplings to tops and gluons, when normalized to the Standard Model (SM), are equal. These properties are shown to be direct consequences of the Goldstone symmetry and of the assumption of partial compositeness. In particular, they are independent of the details of the elementary-composite couplings and, under the further assumption of CP invariance, they are also insensitive to derivative interactions of the Higgs with the composite resonances. We support our conclusions with an explicit construction where the SM fermions are embedded in the 14 dimensional representation of SO(5).