Baryogenesis from neutron-dark matter oscillations

TL;DR

This paper proposes a novel baryogenesis mechanism via neutron-dark matter oscillations at finite temperature, linking dark matter properties with early universe asymmetry transfer and addressing small-scale structure issues.

Contribution

It introduces a model where neutron-dark matter oscillations generate baryon asymmetry, connecting dark matter characteristics with baryogenesis and small-scale structure solutions.

Findings

Resonant oscillations enable baryogenesis before nucleosynthesis.

Dark matter self-interactions suppress small-scale structure problems.

Future CMB experiments can test this scenario.

Abstract

It was recently suggested that dark matter consists of ~GeV particles that carry baryon number and mix with the neutron. We demonstrate that this could allow for resonant dark matter-neutron oscillations in the early universe, at finite temperature, leading to low-scale baryogenesis starting from a primordial dark matter asymmetry. In this scenario, the asymmetry transfer happens around 30 MeV, just before big bang nucleosynthesis. We illustrate the idea using a model with a dark U(1)' gauge interaction, which has recently been suggested as a way of addressing the neutron lifetime anomaly. The asymmetric dark matter component of this model is both strongly self-interacting and leads to a suppression of matter density perturbations at small scales, allowing to mitigate the small-scale problems of cold dark matter cosmology. Future CMB experiments will be able to consistently probe, or firmly exclude, this scenario.