Softened Symmetry Breaking in Composite Higgs Models

Area of Science:

• High Energy Physics
• Particle Physics
• Theoretical Physics

Background:

• Composite Higgs models provide an alternative to the Standard Model Higgs mechanism.
• Explaining the mass of the top quark and the lightness of the Higgs boson are key challenges.
• Existing models often require light top partners, which have not been observed at the Large Hadron Collider (LHC).

Purpose of the Study:

• To propose a new mechanism for breaking Goldstone symmetry in composite Higgs models.
• To reconcile the existence of a light Higgs boson and a heavy top quark with LHC data.
• To avoid the prediction of light top partners near the compositeness scale.

Main Methods:

• Restoring global symmetry in elementary-composite fermion mixings by completing elementary fermions to full symmetry representations.
• Softly breaking Goldstone symmetry via vectorlike mass terms exclusively in the elementary sector.
• Analyzing the phenomenological consequences of this new breaking mechanism.

Main Results:

• The proposed mechanism allows for a light Higgs boson, consistent with LHC observations.
• It naturally accommodates a heavy top quark.
• The model avoids the necessity of light top partners around the Goldstone scale (f ~ TeV).
• The standard scenario is recovered in the limit of infinite vectorlike masses.

Conclusions:

• This new approach offers a viable solution to the hierarchy problem within composite Higgs models.
• It successfully explains key experimental observations at the LHC without invoking unobserved particles.
• The framework provides a pathway to understanding the properties of the Higgs boson and top quark in a composite Higgs scenario.