Probing Miracle-less WIMP Dark Matter via Gravitational Waves Spectral Shapes

TL;DR

This paper explores how gravitational wave spectral shapes from cosmic strings can serve as a novel probe for Miracle-less WIMP dark matter, linking GW signals to dark matter and neutrino physics.

Contribution

It introduces a new method to detect Miracle-less WIMP dark matter through gravitational wave spectral analysis from cosmic strings.

Findings

GW spectral shapes correlate with WIMP mass and symmetry breaking scale.

Late entropy dilution affects GW spectral features.

Predicted GW signals are within reach of future experiments.

Abstract

We propose a novel probe of weakly interacting massive particle (WIMP) dark matter (DM) candidates of a wide mass range which fall short of the required annihilation rates to satisfy correct thermal relic abundance, dubbed as \textit{Miracle-less WIMP}. If the DM interactions are mediated by an Abelian gauge boson like B-L, its annihilation rates typically remain smaller than the WIMP ballpark for very high scale B-L symmetry breaking, leading to overproduction. The thermally overproduced relic is brought within observed limits via late entropy dilution from one of the three right handed neutrinos (RHN) present for keeping the model anomaly free and generating light neutrino masses. Such late entropy injection leads to peculiar spectral shapes of gravitational waves (GW) generated by cosmic strings, formed as a result of B-L symmetry breaking. We find interesting correlation between DM mass and turning frequency of the GW spectrum with the latter being within reach of future experiments. The two other RHNs play major role in generating light neutrino masses and baryon asymmetry of the universe via leptogenesis. Successful leptogenesis with Miracle-less WIMP together restrict the turning frequencies to lie within the sensitivity limits of near future GW experiments.