English

Clockwork Axions in Cosmology: Is Chromonatural Inflation Chrononatural?

High Energy Physics - Theory 2018-11-14 v1 Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology

Abstract

Many cosmological models rely on large couplings of axions to gauge fields. Examples include theories of magnetogenesis, inflation on a steep potential, chiral gravitational waves, and chromonatural inflation. Such theories require a mismatch between the axion field range and the mass scale appearing in the aFF~a F \widetilde{F} coupling. This mismatch suggests an underlying monodromy, with the axion winding around its fundamental period a large number of times. We investigate the extent to which this integer can be explained as a product of smaller integers in a UV completion: in the parlance of our times, can the theory be "clockworked"? We argue that a clockwork construction producing a potential μ4cos(ajFa)\mu^4 \cos(\frac{a}{j F_a}) for an axion of fundamental period FaF_a will obey the constraint μ<Fa\mu < F_a. For some applications, including chromonatural inflation with sub-Planckian field range, this constraint obstructs a clockwork UV completion. Alternative routes to a large coupling include fields of large charge (an approach limited by strong coupling) or kinetic mixing (requiring a lighter axion). Our results suggest that completions of axion cosmologies that explain the large parameter in the theory potentially alter the phenomenological predictions of the model.

Keywords

Cite

@article{arxiv.1806.09621,
  title  = {Clockwork Axions in Cosmology: Is Chromonatural Inflation Chrononatural?},
  author = {Prateek Agrawal and JiJi Fan and Matthew Reece},
  journal= {arXiv preprint arXiv:1806.09621},
  year   = {2018}
}