Seminarium "High Energy, Cosmology and Astro-particle Physics (HECA)"

Cosmological first order phase transitions are intriguing processes with rich phenomenological consequences. They proceed via nucleation of bubbles containing energetically favorable phase in the background of the metastable phase. Such bubbles expand due release of the latent heat, but can be slowed down and even reach the constant subliminal velocity by interactions with the plasma of (not necessarily Standard Model) particles. The terminal velocity determines phenomenological consequences of the transition, since faster walls emit stronger gravitational waves, while slower walls are expected to produce the higher matter-antimatter asymmetry in scenarios of the electroweak baryogenesis, but is much harder to predict than other parameters of the transition. Even though, a significant effort has been undertaken by the community to calculate the velocity from first principles, the final conclusion was still not clear. The recent progress in this field, both numerical and analytical, will be reported in this talk.