Axion Mass from Magnetic Monopole Loops.

Area of Science:

• Theoretical Physics
• Particle Physics
• Cosmology

Background:

• Axions are hypothetical particles that interact with gauge fields.
• Magnetic monopoles are exotic particles predicted by some theories.
• The Witten effect describes how axions can induce electric charge in monopoles.

Purpose of the Study:

• To investigate the potential of axions interacting with Abelian gauge fields and magnetic monopoles.
• To understand the axion potential as an instanton effect.
• To explore the implications for dark matter relic abundance in specific cosmological models.

Main Methods:

• Calculation of the axion potential arising from magnetic monopole loops.
• Analysis of the Witten effect's role in modifying monopole properties.
• Consistency checks involving massless charged fermions and higher-derivative corrections.

Main Results:

• Axions interacting with Abelian gauge fields acquire a potential due to magnetic monopoles.
• This potential can be interpreted as a Euclidean instanton effect.
• The axion potential vanishes with massless charged fermions and is robust against higher-derivative corrections.

Conclusions:

• The study establishes a mechanism for axion potential generation involving magnetic monopoles.
• The findings provide a framework for understanding axion cosmology and dark matter.
• The axion potential's significance in determining dark matter relic abundance is highlighted.