Aspects of Particle Production from Bubble Dynamics at a First Order Phase Transition

TL;DR

This paper investigates particle production mechanisms during first order phase transitions, analyzing bubble dynamics and their implications for gravitational waves and beyond Standard Model physics.

Contribution

It provides the first detailed analysis of particle production at various stages of FOPTs, clarifying underlying physics and addressing subtleties like interaction non-universality and suppression effects.

Findings

Disentangles contributions from bubble nucleation, expansion, and collision.

Discusses non-universality of particle interactions and masses.

Examines suppression of nonperturbative effects such as tachyonic instability.

Abstract

First order phase transitions (FOPTs) constitute an active area of contemporary research as a promising cosmological source of observable gravitational waves. The spacetime dynamics of the background scalar field undergoing the phase transition can also directly produce quanta of particles that couple to the scalar, which has not been studied as extensively in the literature. This paper provides the first careful examination of various aspects of this phenomenon, which is important for understanding the dynamics of the phase transition, the generation of gravitational waves, and various high energy and beyond the Standard Model phenomena. In particular, the contributions from various stages of FOPTs (bubble nucleation, expansion, collision, post-collision) are disentangled, and conceptual aspects of the associated underlying physics relevant for particle production are clarified. Subtleties related to non-universality of particle interactions and masses in different vacua are discussed, and the suppression of nonperturbative effects such as tachyonic instability and parametric resonance due to the inhomogeneous nature of the process is examined.