Light Custodians and Higgs Physics in Composite Models

TL;DR

This paper investigates how light custodial fermions in composite Higgs models affect Higgs couplings, especially to gluons, top, and bottom quarks, impacting Higgs production and decay phenomenology at the LHC.

Contribution

It demonstrates that light custodians significantly alter Higgs couplings to gluons, top, and bottom quarks, with these modifications depending on fermion embedding, providing new insights into composite Higgs phenomenology.

Findings

Higgs-gluon coupling can be increased or decreased by custodians.

Modifications to Hgg, Htt, and Hbb couplings are independent parameters.

Custodians influence Higgs production and decay channels at the LHC.

Abstract

Composite Higgs models involving partial compositeness of Standard Model fermions typically require the introduction of fermionic partners which are relatively light in realistic scenarios. In this paper, we analyze the role of these light custodian fermions in the phenomenology of the composite Higgs models and show that they significantly modify couplings of the Higgs field. We focus on the coupling to gluons in particular, which is of central importance for Higgs production at the LHC. We show that this coupling can be increased as well as decreased depending on the SM fermion embedding in the composite multiplets. We also discuss modification of the Higgs couplings to bottom and top quarks and show that modifications to all these three couplings Hgg, Htt, and Hbb are generically independent parameters.