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Gauge-field production during axion inflation in the gradient expansion formalism

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arxiv 2109.01651 v2 pith:W5XRRJFI submitted 2021-09-03 hep-ph astro-ph.COhep-th

classification hep-phastro-ph.COhep-th
keywords formalismproductiongaugegauge-fieldtimeaxionbackreactionboldsymbol
verification ladder T0 review T1 audit T2 compute T3 formal
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abstract

We study the explosive production of gauge fields during axion inflation in a novel gradient expansion formalism that describes the time evolution of a set of bilinear electromagnetic functions in position space. Based on this formalism, we are able to simultaneously account for two important effects that have thus far been mostly treated in isolation: (i) the backreaction of the produced gauge fields on the evolution of the inflaton field and (ii) the Schwinger pair production of charged particles in the strong gauge-field background. This allows us to show that the suppression of the gauge-field production due to the Schwinger effect can prevent the backreaction in scenarios in which it would otherwise be relevant. Moreover, we point out that the induced current, $\boldsymbol{J} = \sigma \boldsymbol{E}$, also dampens the Bunch-Davies vacuum fluctuations deep inside the Hubble horizon. We describe this suppression by a new parameter $\Delta$ that is related to the time integral over the conductivity $\sigma$ which hence renders the description of the entire system inherently nonlocal in time. Finally, we demonstrate how our formalism can be used to construct highly accurate solutions for the mode functions of the gauge field in Fourier space, which serves as a starting point for a wealth of further phenomenological applications, including the phenomenology of primordial perturbations and baryogenesis.

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Cited by 5 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Axion Inflation: Perturbative control in the strong backreaction regime

    astro-ph.CO 2026-08 conditional novelty 7.0 of 10

    Axion inflation with strong gauge-field backreaction is generically non-perturbative for ξ ≳ 2.5, yet a newly found steady 'mild backreaction' phase at large β can stay perturbatively controlled.

  2. Ab Initio Cosmological Simulations: From Inflation to Present-Day Structure Formation

    astro-ph.CO 2026-07 conditional novelty 7.0 of 10

    Nonlinear axion-U(1) inflation, simulated on a lattice and fed into N-body simulations, boosts small-scale structure and high-redshift halo counts by up to ~200% relative to standard single-field initial conditions.

  3. First-order CP phase transition in two-flavor QCD at $\theta = \pi$ under electromagnetic scale anomaly via a Nambu-Jona-Lasinio description

    hep-ph 2025-02 conditional novelty 6.0 of 10

    In an NJL model, the electromagnetic scale anomaly creates a thermal potential barrier proportional to |eB|^3 |P|/(P^2 + m0^2), making the theta = pi CP transition first order.

  4. Comparative study of the strong backreaction regime in axion inflation: the effect of the potential

    astro-ph.CO 2025-05 conditional novelty 5.0 of 10

    In lattice simulations of axion inflation, the strong-backreaction stage that lengthens inflation occurs for all seven tested potentials, but its duration varies strongly with the potential.

  5. CMB constraints on $U(1)$ axion warm inflation

    astro-ph.CO 2025-07 conditional novelty 4.0 of 10

    Axion-driven warm inflation with U(1) gauge fields is constrained with CMB data and remains viable for sub-Planckian decay constants, but requires large Chern-Simons couplings.

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