We reconsider thermal production of axions in the early universe, including axion couplings to all Standard Model (SM>) particles. Concerning the axion coupling to gluons, we find that thermal effects enhance the axion production rate by a factor of few with respect to previous computations performed in the limit of small strong gauge coupling. Furthermore, we find that the top Yukawa coupling induces a much larger axion production rate, unless the axion couples to SM particles only via anomalies.
Journal of Cosmology and Astroparticle Physics
- Pub Date:
- January 2014
- High Energy Physics - Phenomenology;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- 16 pages, 5 figures. v3: we thank Daniel Green and Benjamin Wallisch for having pointed out a numerical error in the electroweak gauge contribution in fig. 5, which has been corrected