Leptogenesis and Dark Matter Through Relativistic Bubble Walls with Observable Gravitational Waves

TL;DR

This paper proposes a unified scenario where a supercooled phase transition generates masses for dark matter and leptogenesis agents, producing observable gravitational waves and explaining relic abundances.

Contribution

It introduces a minimal conformal model with relativistic bubble walls that simultaneously explains dark matter, leptogenesis, and predicts detectable gravitational waves.

Findings

Relativistic bubble walls can produce sufficient lepton asymmetry.

Supercooling enhances gravitational wave signals within LISA sensitivity.

Inert RHN dark matter is favored over inert scalar doublet.

Abstract

We study a scenario where both dark matter and heavy right handed neutrino (RHN) responsible for leptogenesis acquire masses by crossing the relativistic bubble walls formed as a result of a TeV scale supercooled first order phase transition (FOPT). While this leads to a large out-of-equilibrium abundance of right handed neutrino inside the bubble sufficient to produce the required lepton asymmetry, the dark matter being lighter can still remain in equilibrium with its relic being set by subsequent thermal freeze-out. A classical conformal symmetry ensures the origin of mass via FOPT induced by a singlet scalar while also ensuring supercooling leading to enhanced gravitational wave amplitude within the sensitivity of the LISA experiment. A minimal scenario with three RHN, one inert scalar doublet and one singlet scalar as additional fields beyond the standard model is sufficient to realize this possibility which also favours inert RHN dark matter over inert scalar doublet.