Particle Production in Accelerated Thin Bubbles

TL;DR

This paper studies scalar particle creation inside an accelerating thin bubble boundary in different spacetime backgrounds, revealing how bubble dynamics and curvature influence particle production rates.

Contribution

It provides a unified analysis of particle creation by expanding bubbles in Minkowski and de Sitter spacetimes, highlighting the effects of acceleration, bubble size, and spacetime curvature.

Findings

Particle creation decreases with increasing scalar field mass.

Particle production is more significant in curved spacetimes.

Bubble dynamics and size significantly affect particle creation rates.

Abstract

We investigate the creation of scalar particles inside a region delimited by a bubble which is expanding with non-zero acceleration. The bubble is modelled as a thin shell and plays the role of a moving boundary, thus influencing the fluctuations of the test scalar field inside it. Bubbles expanding in Minkowski spacetime as well as those dividing two de Sitter spacetimes are explored in a unified way. Our results for the Bogoliubov coefficient $\beta_k$ in the adiabatic approximation show that in all cases the creation of scalar particles decreases with the mass, and is much more significant in the case of nonzero curvature. They also show that the dynamics of the bubble and its size are relevant for particle creation, but in the dS-dS case the combination of both effects leads to a behaviour different from that of Minkowski space-time, due to the presence of a length scale (the Hubble radius of the internal geometry).