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Large non-gaussianity in axion inflation
1School of Physics and Astronomy, University of Minnesota, Minneapolis, 55455, USA. barnaby@physics.umn.edu
Physical Review Letters
|June 4, 2011
Summary
Axion inflation models are well-motivated but lack particle physics realization. This study shows that a specific coupling can lead to large non-Gaussianity, potentially exceeding observational limits in realistic scenarios.
Area of Science:
- Cosmology
- Particle Physics
- Theoretical Physics
Background:
- The inflationary paradigm is successful but lacks a concrete particle physics basis.
- Axions are promising candidates for inflation due to their naturally protected potential flatness via shift symmetry.
Purpose of the Study:
- To investigate cosmological perturbations in axion inflation.
- To consistently account for the coupling to gauge fields (cΦFF) in axion inflation models.
- To determine the impact of this coupling on inflaton fluctuations and non-Gaussianity.
Main Methods:
- Reconsideration of cosmological perturbations within axion inflation.
- Consistent inclusion of the axion-field coupling to gauge fields (cΦFF).
- Analysis of gauge quanta production as a source of inflaton fluctuations (δΦ).
Main Results:
- The coupling cΦFF generically leads to the production of gauge quanta.
- These gauge quanta can dominate over vacuum fluctuations for c≥10^2 M(p)^(-1).
- This dominance results in non-Gaussianity exceeding current observational bounds in typical realizations.
Conclusions:
- Axion inflation, when considering the cΦFF coupling, can produce significant non-Gaussianity.
- This effect is prominent in minimal and natural axion inflation models with UV completion.
- The findings challenge simple axion inflation models and suggest observable consequences.
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