The Different Regimes of Axion Gauge Field Inflation

Understand

In axion gauge field inflation an axion-like particle driving cosmic inflation is coupled to the Chern-Simons density of an Abelian or non-Abelian gauge group.

• In the case of a non-Abelian gauge group, this can lead to the formation of a stable, homogeneous and isotropic gauge field background.
• We study the dynamics of the inflaton and gauge fields in terms of the two effective coupling parameters: the gauge coupling and the axion decay constant.
• Starting from the Bunch-Davies vacuum in the far past, we find that the non-trivial gauge field background arises only significantly after the cosmic microwave background (CMB) scales have left the horizon.