# Gravitational waves from non-Abelian gauge fields at a tachyonic transition

## TL;DR

This study investigates gravitational wave production during a tachyonic electroweak-like transition, revealing that non-Abelian gauge fields suppress IR gravitational wave signals, making detection by LISA unlikely.

## Contribution

The paper provides the first large-scale numerical simulation analysis of gravitational waves from a tachyonic non-Abelian gauge field transition, showing the suppression of IR modes.

## Key findings

- Gravitational wave spectrum has two peaks at Higgs and gauge field masses.
- Adding non-Abelian gauge fields reduces IR gravitational wave production.
- Adding Abelian gauge fields increases gravitational wave signals.

## Abstract

We compute the gravitational wave spectrum from a tachyonic preheating transition of a Standard Model-like SU(2)-Higgs system. Tachyonic preheating involves exponentially growing IR modes, at scales as large as the horizon. Such a transition at the electroweak scale could be detectable by LISA, if these non-perturbatively large modes translate into non-linear dynamics sourcing gravitational waves. Through large-scale numerical simulations, we find that the spectrum of gravitational waves does not exhibit such IR features. Instead, we find two peaks corresponding to the Higgs and gauge field mass, respectively. We find that the gravitational wave production is reduced when adding non-Abelian gauge fields to a scalar-only theory, but increases when adding Abelian gauge fields. In particular, gauge fields suppress the gravitational wave spectrum in the IR. A tachyonic transition in the early Universe will therefore not be detectable by LISA, even if it involves non-Abelian gauge fields.