Minimally extended SILH

TL;DR

This paper extends minimal composite Higgs models by adding a composite singlet, analyzing its effects on Higgs physics through an effective field theory approach and comparing with UV models.

Contribution

It introduces the simplest extension of minimal composite Higgs models with a composite singlet and develops rules to estimate operator coefficients.

Findings

The singlet's effects can dominate Higgs physics modifications.

Patterns of new interactions affecting both the singlet and Higgs are identified.

Effective field theory results are supported by comparisons with UV models.

Abstract

Higgs boson compositeness is a phenomenologically viable scenario addressing the hierarchy problem. In minimal models, the Higgs boson is the only degree of freedom of the strong sector below the strong interaction scale. We present here the simplest extension of such a framework with an additional composite spin-zero singlet. To this end, we adopt an effective field theory approach and develop a set of rules to estimate the size of the various operator coefficients, relating them to the parameters of the strong sector and its structural features. As a result, we obtain the patterns of new interactions affecting both the new singlet and the Higgs boson's physics. We identify the characteristics of the singlet field which cause its effects on Higgs physics to dominate over the ones inherited from the composite nature of the Higgs boson. Our effective field theory construction is supported by comparisons with explicit UV models.