Lattice simulations of Abelian gauge fields coupled to axions during Inflation

Kavli Affiliate: Eiichiro Komatsu

| First 5 Authors: Angelo Caravano, Eiichiro Komatsu, Kaloian D. Lozanov, Jochen Weller,

| Summary:

We use a lattice simulation to study a model of axion inflation where the
inflaton is coupled to a U(1) gauge field through Chern-Simons interaction.
These kinds of models have already been studied with a lattice simulation in
the context of reheating. In this work, we focus on the deep inflationary phase
and discuss the new aspects that need to be considered in order to simulate
gauge fields in this regime. Our main result is reproducing with precision the
growth of the gauge field on the lattice induced by the rolling of the axion on
its potential, thus recovering the results of linear perturbation theory for
this model. In order to do so, we study in detail how the spatial
discretization, through the choice of the spatial derivatives on the lattice,
influences the dynamics of the gauge field. We find that the evolution of the
gauge field is highly sensitive to the choice of the spatial discretization
scheme. Nevertheless, we are able to identify a discretization scheme for which
the growth of the gauge field on the lattice reproduces the one of continuous
space with good precision.

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