Multi-messenger FIMP

TL;DR

This paper explores a multi-messenger approach to detect non-thermal FIMP dark matter through effective field theory, linking particle physics experiments and gravitational wave observations to probe early universe conditions and dark matter properties.

Contribution

It introduces a novel framework connecting non-thermal FIMP dark matter with gravitational wave signals from primordial inflation, expanding detection prospects beyond traditional methods.

Findings

Particle physics experiments can probe low reheat temperatures and TeV-scale DM mass.

Future gravitational wave detectors can access a wider parameter space.

Extended reheating scenarios generate observable primordial gravitational waves.

Abstract

We propose a multi-messenger frontier probe of non-thermal or freeze-in massive particle (FIMP) dark matter (DM) by considering an effective field theory (EFT) setup. Assuming leptophilic operators connecting DM with the standard model (SM) bath, we consider DM mass ($m_{\rm DM}$) and the reheat temperature of the Universe ($T_{\rm rh}$) in a regime which prevents DM-SM thermalisation. Low $T_{\rm rh}$ allows sizeable DM-SM interactions even for non-thermal DM allowing the latter to be probed at direct, indirect detection frontiers as well as future electron-positron and muon colliders. An extended reheating period governed by monomial inflaton potential after its slow-roll phase not only generates the required abundance of non-thermal DM via ultraviolet (UV) freeze-in but also brings the scale-invariant primordial gravitational waves (GW) within reach of near future experiments across a wide range of frequencies. While particle physics experiments can probe $T_{\rm rh} \sim O(10)$ GeV and FIMP DM with mass $m_{\rm DM} \sim O(1)$ TeV, future GW detectors are sensitive to a much wider parameter space.