Joint Theory Seminar
Speaker: Harikrishnan Ramani (UC Berekely)
Title: How well do we know the Electroweak Phase Transition?
Host: Verhaaren
Room: 432
Abstract:While, baryogenesis at the electroweak(EW) scale requires the EW phase transition to be first order, the discovery of the 125 GeV Higgs confirms that it is second order in the standard model. A myriad of extensions to the Higgs sector have been proposed to still allow for EW baryogenesis. Most approaches to testing the success of these BSM extensions employ a high temperature, small coupling approximation to estimate the strength of the phase transition and to resum diagrams to all order(also called Daisy diagrams) in order to restore perturbation theory. We relax both these approximations and extend the analysis to temperatures comparable to the EW scale, as well as include 'Super Daisy diagrams' and explore the quantitative implications to certain models. Implications for a no-lose theorem ("how much Higgs precision do we need to falsify EW-baryogenesis?) are also presented.
As an added application of these high accuracy methods, an alternate history of the universe, one in which electroweak symmetry is more badly broken at higher temperatures will also be presented. This non-existent phase transition is the third alternative, the first two being first order and second order phase transitions.
