Gravitational waves from spectator Gauge-flation

Abstract

We investigate the viability of inflation with a spectator sector comprised of non-Abelian gauge fields coupled through a higher order operator. We dub this model "spectator Gauge-flation". We study the predictions for the amplitude and tensor tilt of chiral gravitational waves and conclude that a slightly red-tilted tensor power spectrum is preferred $n_T=-\mathcal{O}(0.01)$. As with related models, the enhancement of chiral gravitational waves with respect to the single-field vacuum gravitational wave background is controlled by the parameter $\gamma =g^2{Q}^2/H^2$, where $g$ is the gauge coupling, $H$ is the Hubble scale and $Q$ is the VEV of the $SU(2)$ sector. The requirement that the $SU(2)$ is a spectator sector leads to a maximum allowed value for $\gamma$, thereby constraining the possible amplification. In order to provide concrete predictions, we use an $\alpha$-attractor T-model potential for the inflaton sector. Potential observation of chiral gravitational waves with significantly tilted tensor spectra would then indicate the presence of additional couplings of the gauge fields to axions, like in the spectator axion-SU(2) model, or additional gauge field operators.

33 pages, 11 figures

References in corpus (8)

• Large Field Inflation and Double $\alpha$-Attractors
• Primordial Gravitational Waves from Axion-Gauge Fields Dynamics
• Planck, LHC, and $\alpha$-attractors
• Higgsed Chromo-Natural Inflation
• Cosmological Attractor Models and Higher Curvature Supergravity
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• SU(2)${}_R$ and its Axion in Cosmology: A common Origin for Inflation, Cold Sterile Neutrinos, and Baryogenesis
• Chiral Anomaly in SU(2)${}_R$-Axion Inflation and the New Prediction for Particle Cosmology

Cited by in corpus (10)

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• Unveiling the nonlinear dynamics of a rolling axion during inflation
• Can primordial parity violation explain the observed cosmic birefringence?
• Lattice simulations of axion-U(1) inflation: gravitational waves, magnetic fields, and scalar statistics
• Magnetogenesis from axion-SU(2) inflation
• Chromo-natural inflation supported by enhanced friction from Horndeski gravity
• Production and backreaction of massive fermions during axion inflation with non-Abelian gauge fields
• Twisting inflation to sub-Planckian axion decay constants