# Baryon-Dark Matter Coincidence in Mirrored Unification

## TL;DR

This paper proposes a mirrored unification model that explains the similar mass densities of dark matter and baryons by linking dark matter to QCD scale and addressing cosmological issues via portal interactions.

## Contribution

It introduces a new mirrored unification framework that breaks mirror-symmetry at the GUT scale and connects dark matter mass to QCD dynamics, solving cosmological problems.

## Key findings

- Dark matter mass linked to QCD scale explains density coincidence.
- Portal interactions transfer asymmetry between sectors.
- Model avoids cosmological issues with entropy release mechanisms.

## Abstract

About 80\% of the mass of the present Universe is made up of the unknown (dark matter), while the rest is made up of ordinary matter. It is a very intriguing question why the {\it mass} densities of dark matter and ordinary matter (mainly baryons) are close to each other. It may be hinting the identity of dark matter and furthermore structure of a dark sector. A mirrored world provides a natural explanation to this puzzle. On the other hand, if mirror-symmetry breaking scale is low, it tends to cause cosmological problems. In this letter, we propose a mirrored unification framework, which breaks mirror-symmetry at the grand unified scale, but still addresses the puzzle. The dark matter mass is strongly related with the dynamical scale of QCD, which explains the closeness of the dark matter and baryon masses. Intermediate-energy portal interactions share the generated asymmetry between the visible and dark sectors. Furthermore, our framework is safe from cosmological issues by providing low-energy portal interactions to release the superfluous entropy of the dark sector into the visible sector.