# Nonperturbative analysis of the gravitational waves from a first-order electroweak phase transition

## TL;DR

This paper provides a nonperturbative analysis of gravitational waves from a first-order electroweak phase transition, showing such signals are generally too weak for detection unless higher-dimension operators or light BSM fields are considered.

## Contribution

It introduces the first end-to-end nonperturbative framework for analyzing gravitational waves from EWPTs using dimensionally reduced effective field theory and compares results with perturbative methods.

## Key findings

- EWPT gravitational wave signals are typically too weak for detection.
- Higher-dimension operators or light BSM fields are needed for observable signals.
- Collider experiments are more promising for exploring phase structure.

## Abstract

We present the first end-to-end nonperturbative analysis of the gravitational wave power spectrum from a thermal first-order electroweak phase transition (EWPT), using the framework of dimensionally reduced effective field theory and pre-existing nonperturbative simulation results. We are able to show that a first-order EWPT in any beyond the Standard Model (BSM) scenario that can be described by a Standard Model-like effective theory at long distances will produce gravitational wave signatures too weak to be observed at existing and planned detectors. This implies that colliders are likely to provide the best chance of exploring the phase structure of such theories, while transitions strong enough to be detected at gravitational wave experiments require either previously neglected higher-dimension operators or light BSM fields to be included in the dimensionally reduced effective theory and therefore necessitate dedicated nonperturbative studies. As a concrete application, we analyze the real singlet-extended Standard Model and identify regions of parameter space with single-step first-order transitions, comparing our findings to those obtained using a fully perturbative method. We discuss the prospects for exploring the electroweak phase diagram in this model at collider and gravitational wave experiments in light of our nonperturbative results.