Asteroid-mass soliton as the dark matter-baryon coincidence solution

Abstract

Nontopological solitons formed during first-order phase transitions can serve as macroscopic dark matter candidates, with their stability ensured by a charge asymmetry traditionally assumed to originate from baryogenesis. Following this generic pattern, we demonstrate that solitogenesis after baryogenesis makes the solitons a coincident dark matter candidate, providing new explanations for the coincidence problem between baryon and dark matter energy densities. We derive a novel and robust conclusion: asteroid-mass coincident soliton dark matter is always accompanied by detectable gravitational waves observable by LISA, $\mu$Ares, and Theia, providing a new candidate beyond primordial black holes in this mass window. Additionally, we propose a simple neutrino-ball scenario that addresses baryon asymmetry, dark matter, and neutrino masses, featuring new particles below the electroweak scale and correlated observable signals, including lensing, gravitational waves, and soliton evaporation or collisions.