Axion inflation in the strong-backreaction regime: decay of the Anber-Sorbo solution
Journal of High Energy Physics 11 (2023) 183 Axion inflation coupled to Abelian gauge fields via a Chern-Simons-like term of the form $\phi F\tilde{F}$ represents an attractive inflationary model with a rich phenomenology, including the production of magnetic fields, black holes, gravitational waves...
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Main Authors | , , , , |
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Format | Journal Article |
Language | English |
Published |
08.09.2023
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Subjects | |
Online Access | Get full text |
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Summary: | Journal of High Energy Physics 11 (2023) 183 Axion inflation coupled to Abelian gauge fields via a Chern-Simons-like term
of the form $\phi F\tilde{F}$ represents an attractive inflationary model with
a rich phenomenology, including the production of magnetic fields, black holes,
gravitational waves, and the matter-antimatter asymmetry. In this work, we
focus on a particular regime of axion inflation, the so-called Anber-Sorbo (AS)
solution, in which the energy loss in the gauge-field production provides the
dominant source of friction for the inflaton motion. We revisit the AS solution
and confirm that it is unstable. Contrary to earlier numerical works that
attempted to reach the AS solution starting from a regime of weak backreaction,
we perform, for the first time, a numerical evolution starting directly from
the regime of strong backreaction. Our analysis strongly suggests that, at
least as long as one neglects spatial inhomogeneities in the inflaton field,
the AS solution has no basin of attraction, not even a very small one that
might have been missed in previous numerical studies. Our analysis employs an
arsenal of analytical and numerical techniques, some established and some newly
introduced, including (1) linear perturbation theory along the lines of
arXiv:2209.08131, (2) the gradient expansion formalism (GEF) developed in
arXiv:2109.01651, (3) a new linearized version of the GEF, and (4) the standard
mode-by-mode approach in momentum space in combination with input from the GEF.
All these methods yield consistent results confirming the instability of the AS
solution, which renders the dynamics of axion inflation in the
strong-backreaction regime even more interesting than previously believed. |
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Bibliography: | ACFI-T23-05, MS-TP-23-38 |
DOI: | 10.48550/arxiv.2309.04254 |