Gauge field production in axion inflation: Consequences for monodromy, non-Gaussianity in the CMB, and gravitational waves at interferometers

Neil Barnaby, Enrico Pajer, Marco Peloso

Research output: Contribution to journalArticlepeer-review

161 Scopus citations

Abstract

Models of inflation based on axions, which owe their popularity to the robustness against uv corrections, have also a very distinct class of signatures. The relevant interactions of the axion are a nonperturbative oscillating contribution to the potential and a shift-symmetric coupling to gauge fields. We review how these couplings affect the cosmological perturbations via a unified study based on the in-in formalism. We then note that, when the inflaton coupling to gauge fields is high enough to lead to interesting observational results, the backreaction of the produced gauge quanta on the inflaton dynamics becomes relevant during the final stage of inflation, and prolongs its duration by about 10 e-foldings. We extend existing results on gravity wave production in these models to account for this late inflationary phase. The strong backreaction phase results in an enhancement of the gravity wave signal at the scales of interferometers. As a consequence, the signal is potentially observable at interferometers such as Advanced LIGO/Virgo for the most natural duration of inflation in such models. Finally, we explicitly compute the axion couplings to gauge fields in string theory construction of axion-monodromy inflation and identify cases where they can trigger interesting phenomenological effects.

Original languageEnglish (US)
Article number023525
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume85
Issue number2
DOIs
StatePublished - Jan 23 2012

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