Speaker
Description
n some theories, defects are metastable and can decay via the nucleation of defects of lower dimensionality through quantum or thermal fluctuations. While at low temperatures the decay is dominated through quantum tunnelling, at higher temperatures thermal decay dominates. Using numerical methods, we simulate defects in a thermal bath at various temperatures and study their thermal decay. In particular, my talk will focus on a 2+1-dimensional model that supports metastable domain walls and vortices connected by these walls. The decay occurs through the nucleation of vortex - anti-vortex pairs along the wall. From a large number of samples, the decay rate is found to be compatible with that expected for a process described by a sphaleron configuration. Studying this model serves as a first step towards understanding how thermal decay impacts the stability of defects in relevant 3+1-dimensional scenarios, such as domain walls bounded by strings in axion models and magnetic monopoles confined by cosmic strings in GUTs. Given the relevance of topological defects in the early Universe, understanding the thermal breaking of such configurations provides important insights into their evolution.