New confining force solution of the QCD axion domain-wall problem

Area of Science:

• Cosmology
• Particle Physics
• String Theory

Background:

• Standard axion models face cosmological issues due to the axion-string-axion-domain-wall system.
• These issues arise from the formation and persistence of domain walls, which can lead to observable cosmological problems.

Purpose of the Study:

• To propose a mechanism that alleviates the cosmological problems associated with axion domain walls.
• To investigate the role of a novel confining force in modifying the behavior of axion strings and domain walls.

Main Methods:

• Theoretical modeling of a new confining force and its instanton effects.
• Analysis of the axion potential generated by the new force.
• Examination of the decay dynamics of domain walls created by this new force.

Main Results:

• The proposed confining force generates an axion potential that erases axion strings before Quantum Chromodynamics (QCD) effects become significant.
• This mechanism effectively prevents the formation of problematic QCD-generated axion walls.
• Domain walls generated by the new confining force decay very early, minimizing their contribution to axion dark matter energy density.

Conclusions:

• The introduction of a new confining force offers a viable solution to the axion domain wall problem in cosmology.
• This model resolves serious cosmological issues by preventing the formation of persistent axion domain walls.
• The early decay of domain walls in this scenario ensures they do not significantly impact the axion dark matter abundance.