Baryon Asymmetry from a Composite Higgs Boson

Area of Science:

• High Energy Physics
• Cosmology
• Particle Physics

Background:

• The nature of the electroweak phase transition (EWPT) is crucial for understanding the early universe.
• Models where the Higgs boson is a pseudo-Nambu-Goldstone boson involve new strongly interacting sectors.
• Previous analyses have not fully considered the interplay between EWPT and the confinement phase transition.

Purpose of the Study:

• To investigate the electroweak phase transition (EWPT) in strongly interacting models where the Higgs is a pseudo-Nambu-Goldstone boson.
• To analyze the scenario where EWPT coincides with the confinement phase transition of the strong sector.
• To explore the implications for electroweak baryogenesis and potential experimental tests.

Main Methods:

• Describing confinement via the dilaton, a pseudo-Nambu-Goldstone boson of broken conformal invariance.
• Analyzing dilaton dynamics for both mesonlike and glueball-like states.
• Examining scale variation of Higgs potential parameters, including the top quark Yukawa coupling.

Main Results:

• The EWPT can be strongly first-order due to the dilaton potential's nearly conformal nature.
• A varying top quark Yukawa coupling during EWPT provides sufficient CP violation for electroweak baryogenesis.
• This CP violation source is consistent with existing flavor and CP constraints.

Conclusions:

• The studied scenario offers a compelling link between strong dynamics, EWPT, and baryogenesis.
• The model predicts testable signatures at colliders (dilaton production, Higgs coupling deviations) and in electron electric dipole moment experiments.
• Gravitational wave signals detectable by LISA could also probe this physics.