A numerical study of pseudoscalar inflation with an axion-gauge field coupling

TL;DR

This paper presents a numerical analysis of pseudoscalar inflation with axion-gauge coupling, demonstrating a warm inflation scenario with a thermal bath, and discusses implications for primordial black hole formation.

Contribution

It provides the first detailed numerical study of axion-gauge field interactions during inflation, including backreaction and thermal effects.

Findings

Establishes a steady thermal bath during inflation due to particle production.

Shows transition to radiation domination without preheating in strong coupling regimes.

Identifies energy density peaks that could lead to primordial black holes.

Abstract

A numerical study of a pseudoscalar inflation having an axion-photon-like coupling is performed by solving numerically the coupled differential equations of motion for inflaton and photon mode functions from the onset of inflation to the end of reheating. The backreaction due to particle production is also included self-consistently. We find that this particular inflation model realizes the idea of a warm inflation in which a steady thermal bath is established by the particle production. In most cases this thermal bath exceeds the amount of radiation released in the reheating process. In the strong coupling regime, the transition from the inflationary to the radiation-dominated phase does not involve either a preheating or reheating process. In addition, energy density peaks produced near the end of inflation may lead to the formation of primordial black holes.