Gravitational wave signatures of PBH-generated baryon-dark matter coincidence

TL;DR

This paper explores how gravitational waves from primordial black hole density fluctuations can reveal the non-thermal origins of baryon asymmetry and dark matter, offering observable signals in current and future GW detectors.

Contribution

It introduces a novel mechanism linking PBH evaporation to baryogenesis and dark matter production, with detectable gravitational wave signatures.

Findings

GW signals from PBH density fluctuations are within reach of current/future detectors.

PBH mass can be as large as 10^7 g, unlike leptogenesis scenarios.

Model offers complementary detection at laboratory experiments.

Abstract

We propose a new way of probing non-thermal origin of baryon asymmetry of universe (BAU) and dark matter (DM) from evaporating primordial black holes (PBH) via stochastic gravitational waves (GW) emitted due to PBH density fluctuations. We adopt a baryogenesis setup where CP violating out-of-equilibrium decays of a coloured scalar, produced non-thermally at late epochs from PBH evaporation, lead to the generation of BAU. The same PBH evaporation is also responsible for non-thermal origin of superheavy DM. Unlike the case of baryogenesis {\it via leptogeneis} that necessarily corners the PBH mass to $\sim\mathcal{O}(1)$ g, here we can have PBH mass as large as $\sim\mathcal{O}(10^7)$ g due to the possibility of producing BAU directly below sphaleron decoupling temperature. Due to the larger allowed PBH mass we can also have observable GW with mHz-kHz frequencies originating from PBH density fluctuations keeping the model constrained and verifiable at ongoing as well as near future GW experiments like LIGO, BBO, DECIGO, CE, ET etc. Due to the presence of new coloured particles and baryon number violation, the model also has complementary detection prospects at laboratory experiments.