LISA as a probe for particle physics: electroweak scale tests in synergy with ground-based experiments

TL;DR

This paper explores how the LISA gravitational wave observatory, in combination with other experiments, can detect and analyze signals from early universe phase transitions, providing insights into particle physics beyond the Standard Model.

Contribution

It demonstrates the potential of LISA and other ground-based experiments to detect gravitational waves from cosmological phase transitions and to determine their energy scales.

Findings

LISA can detect gravitational waves from phase transitions above TeV or below electroweak scale.

LISA can uniquely observe signals from electroweak scale phase transitions.

Parameter reconstruction can identify the timing and energy scale of phase transitions.

Abstract

We forecast the prospective of detection for a stochastic gravitational wave background sourced by cosmological first-order phase transitions. We focus on first-order phase transitions with negligible plasma effects, and consider the experimental infrastructures built by the end of the LISA mission. We make manifest the synergy among LISA, pulsar time array experiments, and ground-based interferometers. For phase transitions above the TeV scale or below the electroweak scale, LISA can detect the corresponding gravitational wave signal together with Einstein Telescope, SKA or even aLIGO-aVIRGO-KAGRA. For phase transitions at the electroweak scale, instead, LISA can be the only experiment observing the gravitational wave signal. In case of detection, by using a parameter reconstruction method that we anticipate in this work, we show that LISA on its own has the potential to determine when the phase transition occurs and, consequently, the energy scale above which the standard model of particle physics needs to be modified. The result may likely guide the collider community in the post-LHC era.