What happens when supercooling is terminated by curvature flipping of the effective potential?

TL;DR

This paper investigates supercooled phase transitions where the effective potential's curvature flip causes the end of supercooling, using lattice simulations to determine if bubble nucleation occurs and exploring potential gravitational wave signals.

Contribution

It provides the first lattice simulation analysis of supercooled phase transitions with curvature flipping, clarifying bubble formation and transition dynamics.

Findings

Scalar field remains trapped at the origin due to potential flatness.

Phase transition proceeds via bubble nucleation and expansion.

Discussion of gravitational wave signals and parameter space for bubble percolation.

Abstract

We explore the nature of a certain type of supercooled phase transition, where the supercooling is guaranteed to end due to the curvature of the finite-temperature effective potential at the origin experiencing a sign flip at some temperature. In such models the potential barrier trapping the scalar field at the meta-stable origin is quickly vanishing at the temperature scale of the phase transition. It is therefore not immediately clear if critical bubbles are able to form, or whether the field will simply transition over the barrier and smoothly roll down to the true minimum. To address this question, we perform lattice simulations of a scalar potential exhibiting supercooling, with a small barrier around the origin, and qualitatively determine the fate of the phase transition. Our simulations indicate that, owing to the required flatness of the potential, the scalar field remains trapped around the origin such that the phase transition generically proceeds via the nucleation and expansion of true-vacuum bubbles. We comment on the possible gravitational wave signals one might expect in a concrete toy model and discuss the parameter space in which bubble percolation is and isn't expected. Animated versions of Figures 6 through 9 can be found at: https://www.youtube.com/playlist?list=PLhT9Np0-FMHBjkejei0bb9qbxbWKHAUXf