Speaker: : Amelia Drew (Cambridge)
Title: Axion String Radiation: the Importance of Curvature
Abstract: Axion strings are topological defects that arise in particle physics models with a spontaneously broken global U(1) symmetry, motivated, for example, by the Peccei-Quinn mechanism. They are predicted to radiate massless dark matter axions, massive particles and gravitational waves. If we are to detect axion dark matter in the post-inflationary symmetry breaking scenario, either directly or indirectly via gravitational waves, understanding the spectrum of the axion radiation emitted from a network of strings will be crucial. In this talk, I will detail my work modelling the dependence of axion string radiation on the curvature of the string relative to the string width. I will focus on my most recent paper, arXiv:2312.07701 (to appear in PRD), which uses adaptive mesh refinement simulations of colliding travelling wave configurations to measure the dependence of massive and massless modes on string curvature. If time allows, I will outline some work in progress on modelling the massive radiation from Nambu-Goto-like cusps using simulations of Abelian-Higgs strings.