How does SU($N$)-natural inflation isotropize the universe?

Abstract

We study the homogeneous and anisotropic dynamics of pseudoscalar inflation coupled to an SU($N$) gauge field. To see how the initially anisotropic universe is isotropized in such an inflation model, we derive the equations to obtain axisymmetric SU($N$) gauge field configurations in Bianchi type-I geometry and discuss a method to identify their isotropic subsets which are the candidates of their late-time attractor. Each isotropic solution is characterized by the corresponding SU(2) subalgebra of the SU($N$) algebra. It is shown numerically that the isotropic universe is a universal late-time attractor in the case of the SU(3) gauge field. Interestingly, we find that a transition between the two distinct gauge-field configurations characterized by different SU(2) subalgebras can occur during inflation. We clarify the conditions for this to occur. This transition could leave an observable imprint on the CMB and the primordial gravitational wave background.

18 pages, 11 figures

References in corpus (8)

• Inflationary Universe with Anisotropic Hair
• Primordial Gravitational Waves from Axion-Gauge Fields Dynamics
• Higgsed Chromo-Natural Inflation
• The isotropic attractor solution of axion-SU(2) inflation: Universal isotropization in Bianchi type-I geometry
• Universality of linear perturbations in SU($N$)-natural inflation
• Dynamics of inflation with mutually orthogonal vector fields in a closed universe
• SU($N$)-natural inflation
• Cosmic No-hair Conjecture and Inflation with an SU(3) Gauge Field

Cited by in corpus (3)

• Misalignment production of vector boson dark matter from axion-SU(2) inflation
• Chromo-natural inflation supported by enhanced friction from Horndeski gravity
• Effective Field Theory of Chiral Gravitational Waves