Speaker
Description
The hydrodynamics of expanding bubbles is a key ingredient in the prediction of gravitational waves from cosmological first-order phase transitions. It fixes which expansion types are possible, and it provides a proxy for how much energy is available for gravitational wave emission. These predictions normally rely on a conformal equation of state, which need not hold in strongly coupled or QCD-like sectors. In this talk, I will relax this assumption and study the self-similar bubble solutions for a family of equations of state that interpolates between electroweak-like and QCD-like transitions. Non-conformality turns out to obstruct bubble expansion, ruling out otherwise admissible solutions and, at the same time, enabling a new expansion mode. I will discuss how both effects reshape the space of solutions and the kinetic energy fraction. If time permits, I will discuss how the collision of bubbles in a QCD-like phase transition leads to a phase-separated final state rather than a homogeneous one.