Lattice-friendly gauge completion of a composite Higgs with top partners

Abstract

We give an explicit example of a composite Higgs model with a pseudo-Nambu-Goldstone Higgs in which the top Yukawa coupling is generated via the partial compositeness mechanism. This mechanism requires composite top partners which are relatively light compared to the typical mass scale of the strongly coupled theory. While most studies of the phenomenology of such models have focused on a bottom-up approach with a minimal effective theory, a top-down approach suggests that the theory should contain a limit in which an unbroken global chiral symmetry protects the mass of the top partners, and the spectrum of the partners satisfies ‘t Hooft matching conditions. We find that the relatively light fermions and pseudo-Goldstone bosons fall into complete multiplets of a large approximate global symmetry, and that the spectrum of particles lighter than a few TeV is non-minimal. Our example illustrates the likely features of a such a composite Higgs theory and also serves as an example of a non-chiral theory with a possible solution to the ‘t Hooft matching conditions. We find in this example that for some low-energy parameters in the effective theory the top partners can decay into high-multiplicity final states, which could be difficult for the Large Hadron Collider (LHC) to constrain. This may potentially allow for the top partners to be lighter than those in more minimal models.