New Target for Cosmic Axion Searches

Area of Science:

• Cosmology and particle physics
• Cosmic Microwave Background (CMB) radiation analysis
• Theoretical physics

Background:

• Future CMB experiments offer subpercent precision in probing relativistic species.
• This sensitivity enables detection of light thermal relics across a wide range of decoupling temperatures.
• Absence of detection implies extra light species were never in thermal equilibrium with the Standard Model.

Purpose of the Study:

• To demonstrate the sensitivity of future cosmological observations to axion couplings.
• To constrain the interactions of axions with photons, gluons, and charged fermions using cosmological data.
• To compare the power of cosmological constraints with existing laboratory and astrophysical bounds.

Main Methods:

• Utilizing the precision of future cosmic microwave background experiments.
• Analyzing the implications of potential relic species on cosmological parameters.
• Calculating constraints on axion-Standard Model couplings based on cosmological observations.

Main Results:

• Future cosmological observations can probe axion couplings to photons, gluons, and charged fermions.
• Cosmological constraints derived from CMB data are expected to significantly outperform current laboratory and astrophysical limits.
• The absence of detected light species would impose stringent limits on new physics beyond the Standard Model.

Conclusions:

• Cosmology provides a powerful, complementary probe for fundamental particle physics, particularly for light species like axions.
• Future CMB experiments will offer unprecedented sensitivity to particle physics, potentially revealing new interactions or ruling out existing theories.
• The study highlights the crucial role of precision cosmology in advancing our understanding of the early universe and fundamental particles.