Gauge Field Production in Axion Inflation: Consequences for Monodromy, non-Gaussianity in the CMB, and Gravitational Waves at Interferometers

By N. Barnaby, E. Pajer, Marco Peloso. 2011

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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 non-perturbative 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 interferometer scales. As a consequence, the signal is potentially observable at 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.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/922c99e1d138142b0406bf87cd82999a17f6c4aa

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Citations in the corpus

Planck 2015 results. XVII. Constraints on primordial non-Gaussianity (2015, unknown): “Recently, the possibility of observable tensor bispectra has been vigorously discussed in a model where the inflaton couples to a pseudoscalar field (Barnaby et al. 2012a; Cook & Sorbo 2013; Ferreira & Sloth 2014).”
Observable non-gaussianity from gauge field production in slow roll inflation, and a challenging connection with magnetogenesis (2012, background): “Moreover, this is correlated also with a gravitational wave signal that can be detectable with interferometers [19, 23].”
A review of axion inflation in the era of Planck (2013, background): “A precise computation of this signal requires taking into account the fact that, for values of ξ that lead to an interesting amount of gravity waves, the final stages of inflation occur in the strong backreaction regime [24].”
Non-Gaussianities and chiral gravitational waves in natural steep inflation (2012, background): “[17, 18, 19, 20] (see also [21]) are however performed in the regime where the backreaction of the gauge field on the rolling inflaton is negligible, and therefore inflation is obtained because V (Φ) (that is otherwise considered to have an arbitrary shape) is sufficiently flat.”
Science with the space-based interferometer LISA. IV: probing inflation with gravitational waves (2016, background): “The power spectrum is related to the fractional GW energy density by [92] ΩGWh 2 = ΩR,0h 2 24 PGW, where ΩR,0h 2 ≡ ρR,0h(2)/3H(2) 0M(2) Pl ' 4.”
CMB at 2 × 2 order: the dissipation of primordial acoustic waves and the observable part of the associated energy release (2012, background): “However, given the large variety of inflationary models (some examples of possible interest are Mukhanov & Chibisov 1981; Silk & Turner 1987; Salopek et al. 1989; Lehners et al. 2007; Ben-Dayan & Brustein 2010; Barnaby et al. 2012), the energy release in theµ- andy-era can differ by a large amount.”
Inflation and String Theory (2014, background): “Besides the model-independent gravitational wave signal, a host of additional modeldependent signatures have been explored, including oscillations in the power spectrum [36], deviations from scale-invariance [759], non-Gaussianity [37, 760], chiral gravitational waves [260,759], and primordial black”