DESY Theory Seminar

Dimensionally reduced EFT approach to the electroweak phase transition

by Tuomas Tenkanen (U Bern)




In a context of electroweak phase transition, we discuss problems of perturbation theory at high temperature, such as Linde's Infrared Problem and issue of renormalisation scale dependence of the effective potential. Although at zero temperature the effective potential is scale independent at one-loop, we show how this breaks down at high temperature and results huge numerical uncertainties for thermodynamics.  To recover renormalisation scale independence at high temperature, we need resummation of the thermal mass to two-loop order, as well as resummation of interaction and kinetic terms. For this, we introduce dimensionally reduced EFT approach, and showcase recent results for electroweak phase transition in scalar extensions of the Standard Model and in particular for primordial gravitational wave production from first order transition.