High Energy Physics Seminar

Generally we do not think about QCD when we try to explain the matter--antimatter asymmetry of the universe. I will describe a small modification to the SM which drastically changes the QCD confinement in the early universe. In this model the strong coupling constant is a dynamical quantity which depends on the vacuum expectation value of a new scalar field. In this history of our Universe the QCD confines through a first-order phase transition at a temperature of T ~ O(100 GeV), when sphalerons are still active. Large CP violation can also exist in the strong sector — which is then cancelled by the QCD axion. I will explain this baryogenesis scenario and the rich set of phase transitions in the model.