Improving Fine-tuning in Composite Higgs Models

Abstract

In this paper we investigate the next-to-minimal composite Higgs model with a SO(6)/SO(5) coset, whose pNGB sector includes a Standard Model singlet in addition to the usual Higgs doublet. The fermions are embedded in the representation 6 of SO(6). We study the region of parameter space of the model where the radiatively generated potential has global minima with both the doublet and the singlet fields developing vacuum expectation values. We investigate the consequences of kinetic and mass mixing between the Higgs and the singlet scalar that arise in this framework. We demonstrate that the ensuing doublet-singlet mixing can provide a handle to accommodate heavier resonances (top-partners) for a given compositeness scale as compared to the minimal composite Higgs model, thus relaxing the tension with the direct LHC bounds. The main phenomenological consequence of this is a sizable deviation of the Higgs couplings from the Standard Model predictions. While the present experimental precision in the measurement of the Higgs couplings still allows for considerable release of this tension, future measurements of the Higgs branching ratios with increased precision would lead to stringent constraints on this setup.

23 pages, 12 figures (pdf), Further clarifications added in text, references updated, matches published version

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• Vacuum misalignment and pattern of scalar masses in the SU(5)/SO(5) composite Higgs model
• Classification of NLO operators for composite Higgs models
• Modelling vector-like quarks in partial compositeness framework
• Relaxation of the Composite Higgs Little Hierarchy
• Convergent Bayesian Global Fits of 4D Composite Higgs Models
• Phase transition and gravitational waves in maximally symmetric composite Higgs model
• Exotic Decays and Collider Signatures of pNGB Scalars in the $SU(5)/SO(5)$ Composite Higgs Model