Probing beyond the Standard Model with gravitational waves from phase transitions

TL;DR

This review discusses how gravitational wave backgrounds from early Universe phase transitions can serve as probes for beyond-Standard-Model physics, highlighting detection prospects with LISA and associated challenges.

Contribution

It summarizes recent analysis on the detectability of gravitational waves from first-order phase transitions and discusses parameter degeneracies affecting model reconstruction.

Findings

LISA can potentially detect signals from early Universe phase transitions.

Degeneracies among parameters hinder precise model reconstruction.

LISA observations can complement collider constraints.

Abstract

This review article is based on a seminar presented at the Higgs pairs workshop 2025. Stochastic gravitational wave backgrounds can serve as probe of the diverse phenomenology encountered in beyond-Standard-Model scenarios featuring phase transitions in the early Universe. Focussing on gravitational wave production from first-order phase transitions, we present the main results of a recent analysis by the LISA Cosmology Working Group concerning the detectability of such signals with LISA. Strong degeneracies, both among the parameters controlling the phase transition and between these and the parameters of the beyond-Standard-Model scenario underlying the phase transition, complicate the reconstruction of the model from a potential signal. Nonetheless, once a specific scenario is assumed, LISA observations can supply constraints possibly complementary to those obtainable from present and future particle colliders.