Vacuum bubbles from cosmic ripples

TL;DR

This paper studies how curvature perturbations in the early Universe influence vacuum decay, revealing that over-densities can accelerate decay and alter bubble dynamics through analytical and numerical methods.

Contribution

It provides a detailed analysis of vacuum decay in curved spacetime with perturbations, including new analytical insights and numerical confirmation of over-density effects.

Findings

Over-densities can trigger earlier vacuum decay.

Large perturbations cause oscillations near the bubble wall.

Analytical and numerical methods agree on the influence of perturbations.

Abstract

We investigate vacuum decays in the early Universe in the presence of curvature perturbations. For sufficiently large perturbations associated with over-densities, we find that the bounce solution develops an oscillating middle stage near the bubble wall. For small perturbations, we analytically show within the thin-wall approximation that an over- (under-) density would enhance (suppress) the vacuum decay rate with a smaller (larger) initial bubble radius. By numerically solving for the bounce solutions and evaluating the corresponding Euclidean action, we further confirm this behaviour in thick-wall cases. Our results indicate that over-densities can generically trigger vacuum decay at an earlier moment.