Cosmological phase transitions: from perturbative particle physics to gravitational waves

TL;DR

This paper reviews the process of connecting particle physics models with gravitational wave signals from early Universe phase transitions, detailing methods from model building to GW spectrum predictions for future detection.

Contribution

It provides a comprehensive, step-by-step review of translating particle physics models into gravitational wave predictions, highlighting current methods and open questions.

Findings

Guidelines for constructing finite-temperature effective potentials

Analysis of bubble dynamics and transition parameters

Predictions for gravitational wave spectra and detectability

Abstract

Gravitational waves (GWs) were recently detected for the first time. This revolutionary discovery opens a new way of learning about particle physics through GWs from first-order phase transitions (FOPTs) in the early Universe. FOPTs could occur when new fundamental symmetries are spontaneously broken down to the Standard Model and are a vital ingredient in solutions of the matter anti-matter asymmetry problem. The purpose of our work is to review the path from a particle physics model to GWs, which contains many specialized parts, so here we provide a timely review of all the required steps, including: (i) building a finite-temperature effective potential in a particle physics model and checking for FOPTs; (ii) computing transition rates; (iii) analyzing the dynamics of bubbles of true vacuum expanding in a thermal plasma; (iv) characterizing a transition using thermal parameters; and, finally, (v) making predictions for GW spectra using the latest simulations and theoretical results and considering the detectability of predicted spectra at future GW detectors. For each step we emphasize the subtleties, advantages and drawbacks of different methods, discuss open questions and review the state-of-art approaches available in the literature. This provides everything a particle physicist needs to begin exploring GW phenomenology.