Speaker
Description
Standard approaches taken in theoretical calculations of phase transition quantities, such as the critical temperature or the bubble nucleation rate, suffer from a wide range of ambiguities: gauge dependence, strong renormalization scale dependence, IR divergences, imaginary potentials… Though a daunting list, these problems can be resolved with the proper methods. The issue is that phase transitions are often influenced by several scales, and that an effective field theory (EFT) approach is needed to separate them. Dimensional reduction can be used to factorize contributions from modes with momenta ~$ \pi T$. There might be further intermediate scales below $ \pi T$ but above the nucleation scale, which also need to be integrated out. A power-counting approach should be undertaken in order to verify that the considered EFT accurately describes the dynamics of bubble nucleation. In this talk, I will demonstrate the use of these methods for calculating observables in a gauge theory with a radiative barrier by comparing calculations of equilibrium quantities in SU(2) + Higgs to lattice data. I will also explain how gauge invariance of the nucleation rate is established. This analysis is generic and can be applied to various cosmological phase transitions, and holds bearing on observables such as the rate of gravitational wave production from the phase transition.
