(keynote speaker)

Axion Inflation in the Lattice

Axion inflation is one the most promising inflationary candidates rooted in particle physics. In this model a pseudo-scalar inflaton in coupled derivatively to gauge fields through an axion coupling. The gauge fields are always excited to high occupation states, both during inflation and during post-inflationary preheating. Due to the large excitation of the gauge fields the system becomes non-linear and enters into the strong backreaction regime. In this talk I will review different approaches to backreaction effects, with a special focus on our recent work: 2303.17436. There the strong backreaction regime is studied using lattice simulations, allowing fully inhomogeneous dynamics and, for the first time, until the end of inflation. I will show that accounting for inhomogeneous effects during backreaction leads to a number of new relevant results. Comparisons with previous spatially homogeneous semi-analytical studies will be also shown. Finally, I will also discuss possible consequences of our results on the phenomenology and observability of axion inflation, including gravitational wave generation and primordial black hole production.