Speaker
Description
If gauge fields are coupled to an axion field during inflation, they can lead to unique observational signatures, such as primordial black holes and sourced gravitational waves. However, this system often shows strong backreaction effects, invalidating the standard perturbation theory approach. In this work, we present the first nonlinear lattice simulation of an axion-U(1) system during inflation. We use it to fully characterize the statistics of the comoving curvature perturbation $\zeta$. We find that non-Gaussianity of $\zeta$ is large in the linear regime, whereas it is suppressed when the dynamics becomes nonlinear. This relaxes bounds from overproduction of primordial black holes, allowing for an observable gravitational waves signal at interferometer scales.
