Speaker Institution: Institute for Theoretical Physics, University Heidelberg
Title: Gravitational Waves from Axion Monodromy
Abstract: Large field inflation is arguably the simplest and most natural variant of slow-roll inflation. Axion monodromy may be the most promising framework for realising this scenario. In this setup, the long-range polynomial potential possesses short-range, instantonic modulations. In this talk we will discuss how such modulations give rise to a series of local minima in the post-inflationary region of the potential. We will then argue that for certain parameter choices the inflaton populates more than one of these vacua inside a single Hubble patch. This corresponds to a dynamical phase decomposition, analogously to what happens in the course of thermal first-order phase transitions. In the subsequent process of bubble wall collisions, the lowest-lying axionic minimum eventually takes over all space. The very interesting signature associated to this violent process is the radiation of gravitational waves. We will provide estimates of the energy density and peak frequency of the signal, which can lie anywhere in the mHz-GHz range, possibly within reach of next-generation interferometers.