Postsphaleron darkogenesis

TL;DR

This paper proposes a darkogenesis mechanism involving a supercooled phase transition in a dark sector, where particle decay during the transition creates matter-antimatter asymmetry, explaining baryon asymmetry, dark matter, and gravitational waves.

Contribution

It introduces a novel scenario where a dark sector phase transition and particle decay generate matter asymmetry, linking dark matter, baryogenesis, and gravitational wave signals.

Findings

Achieves correct baryon asymmetry and dark matter abundance at ~1 GeV phase transition.

Explains nano-Hz gravitational wave signals from pulsar timing arrays.

Predicts testability via neutron-antineutron oscillation experiments.

Abstract

A supercooled phase transition in a nearly conformal dark sector can provide a natural setting for darkogenesis via its out-of-equilibrium dynamics, where a particle-antiparticle number asymmetry in the dark sector can be reprocessed into the visible sector, yielding the observed baryon asymmetry and an asymmetric dark matter. We consider a scenario where the number asymmetry is generated from the decay of a mother particle produced via parametric resonance during the phase transition induced due to its coupling to the dilaton associated with spontaneous breaking of scale invariance. It is shown that the correct baryon asymmetry and dark matter abundance can be realized for a dark phase transition at $\mathcal{O}(1) \, \rm GeV$, which can also explain the nano-Hz gravitational wave signal reported by pulsar timing array experiments. The scenario will be tested further in neutron-antineutron oscillation experiments.