Detection of Early-Universe Gravitational Wave Signatures and Fundamental Physics

TL;DR

This paper surveys potential early-Universe gravitational wave sources like inflation and phase transitions, emphasizing their importance for understanding fundamental physics and their connection to other cosmological probes.

Contribution

It provides a comprehensive overview of early-Universe gravitational wave mechanisms and discusses their relevance to fundamental physics and multimessenger cosmology.

Findings

Identification of key early-Universe GW sources

Discussion of their detectability and scientific significance

Connection to collider and large-scale structure probes

Abstract

Detection of a gravitational-wave signal of non-astrophysical origin would be a landmark discovery, potentially providing a significant clue to some of our most basic, big-picture scientific questions about the Universe. In this white paper, we survey the leading early-Universe mechanisms that may produce a detectable signal -- including inflation, phase transitions, topological defects, as well as primordial black holes -- and highlight the connections to fundamental physics. We review the complementarity with collider searches for new physics, and multimessenger probes of the large-scale structure of the Universe.