The hydrodynamics of inverse phase transitions

TL;DR

This paper investigates the hydrodynamics and energy dynamics of inverse phase transitions, revealing new expansion modes and analyzing bubble wall friction, which are distinct from direct transitions and have implications for cosmological models.

Contribution

It provides the first detailed analysis of the hydrodynamics and energy budget of inverse phase transitions, including new expansion modes and friction effects.

Findings

Identified several expansion modes for inverse bubbles

Discovered a mirror symmetry relating inverse and direct transition modes

Analyzed conditions for runaway bubble walls in inverse transitions

Abstract

First order phase transitions are violent phenomena that occur when the state of the universe evolves abruptly from one vacuum to another. A \emph{direct} phase transition connects a local vacuum to a deeper vacuum of the zero--temperature potential, and the energy difference between the two minima manifests itself in the acceleration of the bubble wall. In this sense, the transition is triggered by the release of vacuum energy. On the other hand, an \emph{inverse} phase transition connects a deeper minimum of the zero--temperature potential to a higher one, and the bubble actually expands against the vacuum energy. The transition is then triggered purely by thermal corrections. We study for the first time the hydrodynamics and the energy budget of inverse phase transitions. We find several modes of expansion for inverse bubbles, which are related to the known ones for direct transitions by a mirror symmetry. We finally investigate the friction exerted on the bubble wall and comment on the possibility of runaway walls in inverse phase transitions.