Colorless Top Partners, a 125 GeV Higgs, and the Limits on Naturalness

Abstract

Theories of physics beyond the Standard Model that address the hierarchy problem generally involve top partners, new particles that cancel the quadratic divergences associated with the Yukawa coupling of the Higgs to the top quark. With extensions of the Standard Model that involve new colored particles coming under strain from collider searches, scenarios in which the top partners carry no charge under the strong interactions have become increasingly compelling. Although elusive for direct searches, these theories predict modified couplings of the Higgs boson to the Standard Model particles. This results in corrections to the Higgs production and decay rates that can be detected at the Large Hadron Collider (LHC) provided the top partners are sufficiently light, and the theory correspondingly natural. In this paper we consider three theories that address the little hierarchy problem and involve colorless top partners, specifically the Mirror Twin Higgs, Folded Supersymmetry, and the Quirky Little Higgs. For each model we investigate the current and future bounds on the top partners, and the corresponding limits on naturalness, that can be obtained from the Higgs program at the LHC. We conclude that the LHC will not be able to strongly disfavor naturalness, with mild tuning at the level of about one part in ten remaining allowed even with 3000 fb${}^{-1}$ of data at 14 TeV.

28 pages plus appendices and references

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Cited by in corpus (13)

• Illuminating Dark Photons with High-Energy Colliders
• The Twin Higgs mechanism and Composite Higgs
• A Holographic Twin Higgs Model
• Next-to-leading order unitarity fits in Two-Higgs-Doublet models with soft ${\mathbb{Z}}_2$ breaking
• Composite Twin Dark Matter
• The Radiative Z2 Breaking Twin Higgs
• Search for single production of the vector-like top partner at the 14 TeV LHC
• Discovering the Twin Higgs Boson with Displaced Decays
• Search for single production of the heavy vectorlike $T$ quark with $T\to th$ and $h\to \gamma \gamma$ at the high-luminosity LHC
• Testing Naturalness
• The Hierarchy Problem: From the Fundamentals to the Frontiers
• A Tale of Two Twin Higgses: Addressing Little Hierarchy in Natural 2HDM Framework
• Signatures of an $S_3$-Orbifold Higgs Model