Abstract

Title : Three-Dimensional Quantum Bubble Collisions

Abstract : First-order phase transitions proceed through the nucleation and subsequent collision of bubbles. In inflationary multiverse scenarios based on false vacuum eternal inflation, such collision events are believed to be ubiquitous and provide a possible avenue to observationally test the multiverse framework. They also play an important role in any early high temperature phase transitions that may have occurred within our local Hubble patch.

I will present results for full three-dimensional collisions between pairs of bubbles, including for the first time the effects of (initially small) quantum fluctuations. In the standard treatment of pairwise collisions, the field profile is assumed to possess SO(2,1) spatial symmetry which reduces the dynamics to a single spatial dimension. Although this profile describes the most likely field configuration, quantum fluctuations do not respect the symmetries. Therefore, the fluctuations require a fully three-dimensional approach. I will show that for a wide class of potentials, the collision dynamics initially drives a linear parametric instability in the fluctuations, causing them to grow exponentially in time. This process is a spatially inhomogeneous version of Bogoliubov particle production. Once the fluctuations become sufficiently large, mode-mode coupling leads to a complete breakdown of the SO(2,1) symmetry. The bubble walls in the collision region dissolve and a population of localized oscillating blobs of field known as oscillons are formed. This has possible implications for the production of gravitational waves or black holes during bubble collisions.