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arXiv · 2411.19892

Kinetic Gauge Friction in Natural Inflation

Martino Michelotti·Rodrigo Gonzalez Quaglia·Ema Dimastrogiovanni·Matteo Fasiello·Diederik Roest
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Abstract

We study an extension of the natural inflation model comprising a non-Abelian gauge sector coupled to the axion-inflaton kinetic term. We show how such non-minimal coupling serves as a source of friction for the rolling inflaton granting sixty or more $e$-folds of accelerated expansion for sub-Planckian values of the axion decay constant. The analysis of perturbations reveals a negative sound speed, thus signaling an instability. Implementing a Chern-Simons-type coupling between the inflaton and gauge sectors cures the instability by delivering a positive speed. We perform a numerical study of scalar and tensor perturbations for a fiducial set of parameters finding that the corresponding observables are compatible with current CMB bounds.

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Martino Michelotti, Rodrigo Gonzalez Quaglia, Ema Dimastrogiovanni, Matteo Fasiello, Diederik Roest. 2024-11-29. Kinetic Gauge Friction in Natural Inflation. https://arxiv.org/abs/2411.19892

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